Copyright: Copyright ®1993 AIM-Software
Citation: Copyright ®1993 AIM-Software


Contents

Notation Used in the Manual

AC Analysis

DC Operating Point

DC Transfer Curve Analysis

Noise Analysis

Pole/Zero Analysis

Transfer Function Analysis

Transient Analysis

Options

Title Line

Comment Line

A   Heterostructure Field Effect Transistors (HFETs)

B   Non-linear Dependent Sources

C   Capacitors

D   Diodes

E   Linear Voltage-Controlled Voltage Sources

F   Linear Current-Controlled Current Sources

G   Linear Voltage-Controlled Current Sources

H   Linear Current-Controlled Voltage Sources

I   Independent Current Sources

J   Junction Field-Effect Transistors (JFETs)

K   Coupled Inductors (transformers)

L   Inductors

M   Metal Oxide Semiconductor Field Effect Transistors (MOSFETs)

N   Heterojunction Bipolar Transistors (HBTs)

O   Lossy Transmission Lines  (LTRA)

Q   Bipolar Junction Transistors (BJTs)

R   Resistors

S   Voltage Controlled Switch

T   Transmission Lines (Lossless)

U   Uniform Distributed RC Lines (URC)

V   Independent Voltage Sources

W   Current Controlled Switch

Z   GaAs Metal Semiconductor Field Effect Transistors (MESFETs)

.INCLUDE statement

.SUBCKT statement

.ENDS statement

Call to subcircuits

.NODESET statement

.IC statement

Bugs Reported by Berkeley

References


Notation Used in the Manual

Item	Example	Description
name	M12	A name field is an alphanumeric string.  It must begin with a letter and cannot contain any delimiters.
node	5000	A node field may be arbitrary character strings. The ground node must be named '0'. Node names are treated as character strings, thus '0' and '000' are different names.
scale suffix		T=1012, G=109, MEG=106, K=103, MIL=25.4⋅10-6, M=10-3, U=10-6, N=10-9, P=10-12, F=10-15
units suffix	V	Any letter that is not a scale factor or any letters that follows a scale suffix
value	1KHz	Floating-point number with optional scale and/or units suffixes
(text)	(option)	Comment
<item>	<OFF>	Optional item
{item}	{model}	Required item


AC Analysis

AC analysis is used to calculate the frequency response of a circuit over a range of frequencies.

DEC , OCT, and LIN stand for decade, octave variation and linear variation, respectively. The specification of number of points changes with the selection made. If DEC is specified, the number of points are per decade. If OCT is specified, the number of points are per octave. If LIN is specified, the number of points are the total number across the whole frequency range. The frequency range is specified with the Start Frequency and End Frequency parameters. Note that in order for this analysis to be meaningful, at least one independent source must be specified with an ac value.

If the circuit has only one ac input, it is convenient to set that input to unity and zero phase. Then the output variable will be the transfer function of the output variable with respect to the input.


DC Operating Point

This analysis calculates the dc operating point of a circuit. It has no parameters.


DC Transfer Curve Analysis

In a DC Transfer Curve analysis, one or two source(s) (voltage or current sources) are swept over a user defined interval. The dc operating point of the circuit is calculated for every value of the source(s).

Source Name is the name of an independent voltage or current source, Start Value, End Value and Increment Value are the starting, final and increment values respectively. In the example above, the voltage source vds is swept from 0 V to 5 V in increments of 0.1 V. A second source may optionally be specified with associated sweep parameters. In such a case, the first source is swept over its range for each value of the second source. This option is useful for obtaining semiconductor device output characteristics.


Distortion Analysis
Distortion Analysis (Not available yet)

The distortion analysis part of AIM-Spice calculates steady-state harmonic and intermodulation products for small signal input magnitudes.

The dialog box for this analysis is almost identical to the AC analysis dialog box except for the last parameter F2 over F1. This is an optional parameter and if not specified, the distortion analysis performs a harmonic analysis - i.e., it analyses distortion in the circuit using only a single input frequency F1, which is swept as specified by the frequency parameters exactly as in the AC analysis. Inputs at this frequency may be present at more than one input source, and their magnitudes and phases are specified by the arguments of the DISTOF1 keyword on the instance lines for the input sources (see the description for independent sources). The analysis produce information about the AC values of all node voltages and branch currents at the harmonic frequencies 2F1 and 3F1, vs. the input frequency F1 as it is swept. (A value of 1 (as a complex distortion output) signifies cos(2π(2F1)t) at 2F1 and cos(2π(3F1)t) at 3F1, using the convention that 1 at the input fundamental frequency is equivalent to cos(2πF1t).) The distortion component desired (2F1 or 3F1) can be selected using the postprocessor, and then printed. (Normally, one is interested primarily in the magnitude of the harmonic components, so the magnitude of the AC distortion value is looked at). It should be noted that these are the AC values of the actual harmonic components, and are not equal to HD2 and HD3. To obtain HD2 and HD3, one must divide by the corresponding AC values at F1, obtained from an AC analysis.

If the optional F2 over F1 parameter is specified, it should be a real number between (and not equal to) 0.0 and 1.0. In this case a spectral analysis is performed. It considers the circuit with sinusoidal inputs at two different frequencies F1 and F2. F1 is swept according to the frequency parameters in the dialog box. F2 is kept fixed at a single frequency as F1 sweeps - the value at which it is kept fixed is equal to "F2 over F1" times the Start frequency. Each independent source in the circuit may potentially have two (superimposed) sinusoidal inputs for distortion, at the frequencies F1 and F2. The magnitude and phase of the F1 component are specified by the arguments of the DISTOF1 keyword in the source's element line (see the description of independent sources). The magnitude and phase of the F2 component are specified by the arguments of the DISTOF2 keyword. The analysis produces plots of all node voltages/branch currents at the intermodulation product frequencies F1+F2, F1-F2, and 2F1 - F2, vs. the swept frequency F1. The IM product of interest may be selected and displayed/printed in the postprocessor.. It is to be noted as in the harmonic analysis case, the results are the actual AC voltages and currents at the intermodulation frequencies, and need to be normalized with respect to .AC values to obtain the IM parameters.

If the DISTOF1 or DISTOF2 keywords are missing from the description of an independent source, then that source is assumed to have no input at the corresponding frequency. The default values of the magnitude and phase are 1.0 and 0.0 respectively. The phase should be specified in degrees.

It should be carefully noted that the number  specified for the F2 over F1 parameter should ideally be an irrational number, and since this is not possible in practice, efforts should be made to keep the denominator in its fractional representation as large as possible, certainly above 3, for accurate results (i.e. the parameter is represented as a fraction A/B where A and B are integers with no common factors, B should be as large as possible. Note that A<B because the parameter is constrained to be < 1). To illustrate  why, consider the cases where the parameter is 49/100 and 1/2. In a spectral analysis, the outputs produced are at F1+F2, F1-F2 and 2F1 -F2. In the latter case, F1-F2=F2, so the results at the F1-F2 component is erroneous because there is the strong fundamental F2 component at the same frequency. Also, F1+F2=2F1-F2 in the latter case, and each result is erroneous individually. This problem is not there in the case where the parameter "F2 over F1" is 49/100. In this case, there are two very closely spaced frequency components at F2 and F1-F2. One of the advantages of the Volterra series technique is that it computes distortions at mix frequencies expressed symbolically, therefore one is able to obtain the strengths of distortion components accurately even if the separation between them is very small, as opposed to the transient analysis for example. The disadvantage is of course that if two of the mix frequencies coincide, the results are not merged together and presented. Currently, the interested user should keep track of this mix frequencies himself or herself and add the distortions at coinciding mix frequencies together should it be necessary.


Noise Analysis

Noise Analysis computes device-generated noise in a circuit.

The "Output Noise Variable" parameter has the form V(OUTPUT<,REF>) where OUTPUT is the node at which the total output noise is desired. If REF is specified, the noise voltage V(OUTPUT) - V(REF) is calculated. By default, REF is assumed to be ground. In "Input Source", the name of an independent source to which input noise is referred, is specified. The next three parameters are the same as for AC Analysis. The last parameter is an optional integerif specified, the noise contribution of each noise generator is produced every "Points per Summary" frequency point.

This analysis produces two plots. One for the Noise Spectral Density curves and one for the total Integrated Noise over the specified frequency range. All noise voltages/currents are in squared units (V2/Hz and A2/Hz for spectral density, V2 and A2 for integrated noise).


Pole/Zero Analysis

The Pole-Zero Analysis computes poles and/or zeros in the small signal ac transfer function. You may instruct AIM-Spice locate only poles or only zeros. This feature may allow one of the sets to be determined if there is a convergence problem with finding both.


Transfer Function Analysis

When you select this analysis, AIM-Spice computes the DC small signal value of the transfer function, the input resistance, and the output resistance.

In the example shown in the dialog box above, AIM-Spice will compute the ratio v(8) to vin, the small-signal input resistance at vin, and the small-signal output resistance measured across nodes 8 and 0.


Transient Analysis

The Transient Analysis in AIM-Spice computes the time domain response of a circuit.

The parameter Stepsize is the suggested computing increment, Final Time is the last time point computed. Transient analysis always starts at time zero. If you are not interested in the results until at a later time, you specify this time with the parameter Display Start Time. The parameter Maximum Stepsize is useful when you want to limit the internal stepsize used by AIM-Spice.

When selecting the Use Initial Conditions (UIC) option, you indicates that you do not want AIM-Spice to solve for the quiescent operating point before starting the Transient Analysis. Initial transient conditions can then be specified in the circuit description using an IC= control command.  Alternatively, an .IC statement can be entered, specifying node voltages used to compute the initial conditions for the devices.  (When UIC is not selected, the .IC and the IC= statements have no effect.)


Options

A set of options that controls different aspects of a simulation is available through the Options menu. The options are divided between the following four logical groups:

  General

  Analysis specific

  Device specific

  Numeric specific

Each option group has a separate dialog box. The options are listed in the table below. The numbers in parentheses indicate to which group they belong.

Option	Description	Default
GMIN	Minimum allowed conductance (1)	1.0E-12
RELTOL	Relative error tolerance (1)	0.001
ABSTOL	Absolute current error tolerance (1)	1nA
VNTOL	Absolute voltage error tolerance (1)	1μV
CHGTOL	Charge tolerance (1)	1.0E-14
TNOM	Nominal temperature. The value can be overridden by a temperature specification on any temperature dependent device model. (1)	27
TEMP	Operating temperature of the circuit. The value can be overridden by a temperature specification on any temperature dependent instance. (1)	27
TRYTOCOMPACT	Applicable only to the LTRA model. When specified, the simulator tries to condense LTRA transmission lines past history of input voltages and currents (1).	Not Set
TRTOL	Transient analysis error tolerance (2)	7.0
ITL1	Maximum number of iterations in computing the dc operating point (2)	100
ITL2	Maximum number of iterations in dc transfer curve analysis (2)	50
ITL4	Transient analysis timepoint iteration limit (2)	10
DEFL	Default channel length for a MOS-transistor (3)	100μm
DEFW	Default channel width for a MOS-transistor (3)	100μm
DEFAD	Default drain diffusion area for a MOS-transistor (3)	0.0
DEFAS	Default source diffusion area for a MOS-transistor (3)	0.0
PIVTOL	Minimum value for an element to be accepted as a pivot element. (4)	1.0E-13
PIVREL	The minimum relative ratio between the largest element in the column and a accepted pivot element (4)	1.0E-13
METHOD	Sets the numerical integration method used by AIM-Spice. Possible methods are Gear or Trapezoidal. (4)	Trap


Title Line

General form:

Any text

Example:

SIMPLE DIFFERENTIAL PAIR

MOS OPERATIONAL AMPLIFIER

The title line must be the first line in the circuit description.


Comment Line

General form:

*(any text)

Example:

* MAIN CIRCUIT STARTS HERE

An asterisk in the first column indicates that this line is a comment line. Comment lines may be placed anywhere in the circuit description.


A   Heterostructure Field Effect Transistors (HFETs)

General form:

AXXXXXXX ND NG NS MNAME <L=VALUE> <W=VALUE> <TEMP=VALUE> <OFF>

+ <IC=VDS,VGS>

Example:

a1 7 2 3 hfeta l=1u w=10u

ND, NG and NS are the drain, gate and source nodes, respectively. MNAME is the model name, L is the channel length, W is the channel width, and OFF indicates an optional initial value for the element in a dc analysis. The optional TEMP value is the device operating temperature in degrees centigrade and overrides the temperature specified in the option value. The optional initial value IC=VDS,VGS is meant to be used together with UIC in a transient analysis. See the description of the .IC statement for a better way to set transient initial conditions.  If  length and/or width is not specified, AIM-Spice will use default values, L=1μm and W=20μm.

HFET Model

.MODEL {model name} NHFET <model parameters>

.MODEL {model name} PHFET <model parameters>

AIM-Spice supports two HFET models. The parameter LEVEL selects which model to use. The default is LEVEL=1.

HFET Level 1 Model

The HFET level 1 model is a unified extrinsic model as described in section 4.6 in [2]. The model parameters are listed below. Note that the default values used correspond to the device used as an example in section 4.6 in [2].

Name	Parameter	Units	Default

Drain Current Parameters

D1	Distance to buffer layer charge	m	0.03E-6
D2	Distance from gate to second channel	m	0.2E-6
DELTA	Transition width parameter	-	3
DELTAD	Thickness correction	m	4.5E-9
DI	Thickness of interface layer	m	0.04E-6
EPSI	Dielectric constant for interface layer	F/m	1.0841E-10
ETA	Subthreshold ideality factor	-	1.28 (NHFET) 1.4 (PHFET)
ETA1	Ideality factor of buffer layer charge	-	2.0
ETA2	Ideality factor of second channel conduction	-	2.0
KLAMBDA	Temperature coefficient of LAMBDA	1/(V°C)	0
KMU	Temperature coefficient of MU		0
KVTO	Temperature coefficient of VTO	V/°C	0
LAMBDA	Output conductance parameter	1/V	0.15
M	Knee shape parameter	-	3
MU	Low field mobility		0.4 (NHFET) 0.03 (PHFET)
NMAX	Maximum sheet charge density in the channel		2E16
RD	Drain ohmic resistance	Ω	0
RDI	Internal drain ohmic resistance	Ω	0
RS	Source ohmic resistance	Ω	0
RSI	Internal source ohmic resistance	Ω	0
SIGMA0	DIBL parameter	-	0.057
VS	Saturation velocity	m/s	1.5E5 (NHFET) 0.8E5 (PHFET)
VSIGMA	DIBL parameter	V	0.1
VSIGMAT	DIBL parameter	V	0.3
VT1	Threshold voltage of interface layer conduction	V	Calculated
VT2	Threshold voltage of second channel	V	VTO
VTO	Threshold voltage	V	0.15 (NHFET) -0.15 (PHFET)

Gate Current Parameters

A1	First correction current coefficient	-	0
A2	Second correction current coefficient	-	0
ALPHAT	Drain temperature coefficient		0
ASTAR	Effective Richardson constant		4.0E4
CK1	First drain temperature coefficient	-	1
CK2	Second drain temperature coefficient	V	0
CM1	Third drain temperature coefficient	-	3
CM2	Fourth drain temperature coefficient	V	0
CM3	Third correction current coefficient	-	0.17
DEL	Reverse junction conductance inverse ideality factor	-	0.04
GATEMOD	Gate leakage current model selector	-	0
GGR	Junction conductance at reverse bias		40
JS1S	Forward gate source diode saturation current density		1.0
JS2D	Reverse gate drain diode saturation current density		1.15E6
JS2S	Reverse gate source diode saturation current density		1.15E6
M1D	Forward gate drain diode ideality factor	-	1.32
M1S	Forward gate source diode ideality factor	-	1.32
M2D	Reverse gate drain diode ideality factor	-	6.9
M2S	Reverse gate source diode ideality factor	-	6.9
MT1	First drain temperature exponent	-	3.5
MT2	Second drain temperature exponent	-	9.9
MV1	Correction current exponent	-	3
PHIB	Effective heterojunction barrier height	eV	0.5
RG	Gate ohmic resistance	Ω	0
RGD	Gate-drain ohmic resistance	Ω	90
RGS	Gate-source ohmic resistance	Ω	90

AC Parameters

CDS	Drain-source capacitance	F	0
DELF	gds transition width	Hz	0.0
FGDS	Transition frequency for gds	Hz	0.0
GAMMA	Capacitance parameter	-	3
KAPPA	Determines the relative increase in gds at high frequencies	-	0.0
MC	Capacitance transition parameter	-	3
P	Charge partitioning parameter	-	1.0
RF	Resistance in series with Cgd	Ω	0
RI	Resistance in series with Cgs	Ω	0
TF	Characteristic temperature for the frequency dependence of gds	°C	TEMP
Either intrinsic or extrinsic models can be selected by proper use of the parameters RD, RS, RDI, and RSI. If values for RD and RS are specified, the intrinsic model is selected with parasitic resistances applied externally. The extrinsic model is selected by specifying values for RDI and RSI.

Supported Analyses

Distortion, Noise, and Pole-Zero Analysis not supported.

Temperature effects

The temperature appears explicitly in the several exponential terms. In addition, the temperature dependence of several key parameters are modeled as shown below (in terms of absolute temperatures).

The dependence of the threshold voltage on temperature is modeled by the equation

where TNOM is the nominal temperature specified as an option.

The mobility and output conductance are adjusted according to:

Frequency dependent output conductance

The output conductance gds depends on the frequency. In a small-signal AC analysis, gds is modified according to the following equations:

Equivalent circuit (GATEMOD = 0)

Figure A1

Equivalent circuit (GATEMOD = 1)

Figure A2

Drain current equations

Calculation of total inversion charge

If second channel parameters (ETA2 and D2) are not given:

else

where

Gate current equations (GATEMOD = 0)

When specifying GATEMOD = 0, the gate leakage current is modeled as two diode paths from gate to drain and from gate to source as shown in Figure A1.  Each diode path contains a series combination of a parasitic resistance and two ideal diodes.  The four diodes are labeled D1D, D2D, D1S and D2S. The table below shows the ideal diode model parameters for each diode.

Diode	Ideality factor	Reverse saturation current density
D1D	M1D	JS1D
D2D	M2D	JS2D
D1S	M1S	JS1S
D2S	M2S	JS2S

The current through an ideal diode is given by

where Is is the reverse saturation current and m is the ideality factor.

Gate current equations (GATEMOD = 1)

When GATEMOD = 1 is specified, the effects of hot-electrons near the drain side of the channel is accounted. The equivalent circuit is shown in Figure A2. Note that it contains only the diodes which represent the heterojunction, and hence, it may not describe the gate current at low current levels for some devices.

Gate current at reverse gate bias

Correction current

If GATEMOD = 0, the correction current is zero. If GATEMOD = 1 is specified, the correction current is given by the following equations:

Capacitance equations

If VT1 is not specified, VT1 is calculated using the following expression:

HFET Level 2 Model

The HFET level 2 model is a simplified version of the level 1 model.  The model is optimized for speed and is suitable for simulation of digital circuits.  To increase the speed, some of the features included in the level 1 model is not implemented for the level 2 model.  The model parameters are listed below.

Name	Parameter	Units	Default

Drain Current Parameters

Same as for level 1

Gate Current Parameters

DEL	Reverse junction conductance inverse ideality factor	-	0.04
GGR	Junction conductance at reverse bias		0
JS	Forward bias saturation current		0
N	Forward bias ideality factor	−	1

AC Parameters

CF	Fringing capacitance	F	0
GAMMA	Capacitance parameter	-	3
MC	Capacitance transition parameter	-	3
P	Charge partitioning parameter	-	1.0
Either intrinsic or extrinsic models can be selected by proper use of the parameters RD, RS, RDI, and RSI. If values for RD and RS are specified, the intrinsic model is selected with parasitic resistances applied externally. The extrinsic model is selected by specifying values for RDI and RSI.

Supported Analyses

Distortion, Noise, and Pole-Zero Analysis not supported.

Equivalent circuit

Drain current equations

Same as for level 1.

Gate current equations

Capacitance equations

Same as for level 1 except for that the fringing capacitance is specified as a model parameter and is not calculated.


B   Non-linear Dependent Sources

General form:

BXXXXXXX N+ N- <I=EXPR> <V=EXPR>

Example:

b1 0 1 i=cos(v(1))+sin(v(2))

b1 0 1 v=ln(cos(log(v(1,2)^2)))-v(3)^4+v(2)^v(1)

b1 3 4 i=17

b1 3 4 v=exp(pi^i(vdd))

N+ and N- are the positive and negative nodes respectively. The values of the V and I parameters determine the voltages and currents across and through the device respectively. If I is given then the device is a current source, and if V is given the device is a voltage source. One and only one of these parameters must be given.

During an AC analysis, the source acts as a linear dependent source with a proportionality constant equal to the derivative of the source at the DC operating point.

The expressions given for V and I may be any function of node voltages and/or currents through voltage sources in the system. The following are allowed functions of real variables:

abs	asinh	cosh	sin

acos	atan	exp	sinh

acosh	atanh	ln	sqrt

asin	cos	log	tan

The following operations are defined:

+	-	*	/	^	unary -

If the argument of log, ln, or sqrt becomes less than zero, the absolute value of the argument is used. If a divisor becomes zero or the argument of log or ln becomes zero, an error will result. Other problems may occur when the argument of a function in a partial derivative enters a region where that function is undefined.

To introduce time into an expression, you can integrate the current from a constant current source with a capacitor and use the resulting voltage.  For a correct result, you have to set the initial voltage across the capacitor.

Non-linear capacitors, resistors, and inductors may be synthesized using non-linear dependent sources.  Here is an example on how to implement a non-linear capacitor:

* Bx: calculate f(input voltage)

Bx 1 0 v=f(v(pos,neg))

* Cx: linear capacitance

Cx 2 0 1

* Vx: Ammeter to measure current into the capacitor

Vx 2 1 DC 0 Volts

* Drive the current through Cx back into the circuit

Fx pos neg Vx 1

Supported Analyses

All


C   Capacitors

General form:

CXXXXXXX N+ N- VALUE <IC=Initial values>

Examples:

cl 66 0 70pf

CBYP 17 23 10U IC=3V

N+ and N- are the positive and negative element nodes respectively. VALUE is the capacitance in Farads.

The optional initial value is the initial time zero value of the capacitor voltage in Volts. Note that the value is used only when the option UIC is specified in a transient analysis.

Semiconductor Capacitors

General form:

CXXXXXXX N1 N2 <VALUE> <MNAME> <L=LENGTH> <W=WIDTH>

+ <IC=VALUE>

Examples:

CMOD 3 7 CMODEL L=10U W=1U

This is a more general model for the capacitor than the one presented above.  It gives you the possibility of modeling temperature effects and calculating capacitance values based on geometric and process information.  VALUE if given, defines the capacitance, and information on geometry and process will be ignored.  If MNAME is specified, the capacitance value is calculated based on information on process and geometry.  If VALUE is not given, then MNAME and LENGTH must be specified.  If WIDTH is not given, then the model default width will be used.

Capacitor Model

.MODEL {model name} C <model parameters>

The model allows calculation of the capacitance based on information on geometry and process by the expression:

where the parameters are defined below.

Name	Parameter	Unit	Default
CJ	Junction bottom capacitance		-
CJSW	Junction sidewall capacitance	F/m	-
DEFW	Default width	m	1e-6
NARROW	Narrowing due to side etching	m	0.0
Supported Analyses

All


D   Diodes

General form:

DXXXXXXX N+ N- MNAME <AREA> <OFF> <IC=VD> <TEMP=T>

Examples:

DBRIDGE 2 10 DIODE1

DCLMP 3 7 DMOD 3.0 IC=0.2

N+ and N- are the positive and negative nodes, respectively. MNAME is the model name, AREA is the area factor, and OFF indicates an optional initial value during a dc analysis. If the area factor is not given, 1 is assumed. The optional initial value IC=VD is meant to be used together with an UIC in a transient analysis. The optional TEMP value is the temperature at which this device is to operate. It overrides the temperature specified as an option.

Diode Model

.MODEL {model name} D <model parameters>

AIM-Spice has 2 diode models. Level 1, the default model, is an expanded version of the standard diode model supplied from Berkeley (extended to include high-level injection and generation/ recombination current). Level 2 is a GaAs/AlGaAs heterostructure diode model described in section 1.10 in [2]. To select the heterostructure diode model specify LEVEL=2 on the model line.

Level 1 model parameters are:

Name	Parameter	Units	Default
IS	Saturation current (level 1 only)	A	1.0e-14
RS	Ohmic resistance	Ω	0
N	Emission coefficient	-	1
TT	Transit time	s	0
CJO	Zero bias junction capacitance	F	0
VJ	Junction potential	V	1
M	Grading coefficient	-	0.5
EG	Activation energy	eV	1.11
IKF	Corner for high injection current roll-off	A	infinite
ISR	Recombination saturation current	A	0
NR	Recombination emission coefficient	-	2
XTI	Saturation current temperature exponent	-	3.0
KF	Flicker noise coefficient	-	0
AF	Flicker noise exponent	-	1
FC	Coefficient for forward-bias depletion capacitance formula	-	0.5
BV	Reverse breakdown voltage	V	infinite
IBV	Current at breakdown voltage	A	1.0e-3
TNOM	Parameter measurement temperature	°C	27

Level 2 model parameters are (in addition to those for level 1):

Name	Parameter	Units	Default
DN	Diffusion constant for electrons		0.02
DP	Diffusion constant for holes		0.000942
LN	Diffusion length for electrons	m	7.21e-5
LP	Diffusion length for holes	m	8.681e-7
ND	Donor doping density		7.0e24
NA	Acceptor doping density		3e22
DELTAEC	Conduction band discontinuity	eV	0.6
XP	p-region width	m	1μm
XN	n-region width	m	1μm
EPSP	Dielectric constant on p-side	F/m	1.0593e-10
EPSN	Dielectric constant on n-side	F/m	1.1594e-10
Temperature Effects

Temperature appears explicitly in the exponential terms.

Temperature dependence of the saturation current in the junction diode model is determined by:

where k is Boltzmann's constant, q is the electronic charge, EG is the energy gap (in eV), XTI is the saturation current temperature exponent, and N is the emission coefficient. The last three quantities are model parameters.

For Schottky barrier diodes, the value for XTI is usually 2.

Supported Analyses

All


E   Linear Voltage-Controlled Voltage Sources

General form:

EXXXXXXX N+ N- NC+ NC- VALUE

Example:

E1 2 3 14 1 2.0

N+ and N- are the positive and negative nodes, respectively. NC+ and NC- are the positive and negative controlling nodes, respectively. VALUE is the voltage gain.

Supported Analyses

All


F   Linear Current-Controlled Current Sources

General form:

FXXXXXXX N+ N- VNAME VALUE

Example:

F1 14 7 VIN 5

N+ and N- are the positive and negative nodes, respectively. Current flows from the positive node through the source to the negative node. VNAME is the name of the voltage source where the controlling current flows. The direction of positive control current is from positive node through the source to the negative node of VNAME. VALUE is the current gain.

Supported Analyses

All


G   Linear Voltage-Controlled Current Sources

General form:

GXXXXXXX N+ N- NC+ NC- VALUE

Example:

G1 2 0 5 0 0.1MMHO

N+ and N- are the positive and negative nodes, respectively. Current flows from the positive node through the source to the negative node. NC+ and NC- are the positive and negative controlling nodes, respectively. VALUE is the transconductance in mhos.

Supported Analyses

All


H   Linear Current-Controlled Voltage Sources

General form:

HXXXXXXX N+ N- VNAME VALUE

Example:

HX1 6 2 Vz 0.5K

N+ and N- are the positive and negative nodes, respectively. Current flows from the positive node through the source to the negative node. VNAME is the name of the voltage source where the controlling current flows. The direction of positive control current is from positive node through the source to the negative node of VNAME. VALUE is the transresistance in ohm.

Supported Analyses

All


I   Independent Current Sources

General form:

IYYYYYYY N+ N- <<DC> DC/TRAN VALUE> <AC <ACMAG <ACPHASE>>>

+ <DISTOF1 <F1MAG <F1PHASE>>> <DISTOF2 <F2MAG <F2PHASE>>>

Examples:

isrc 23 21 ac 0.333 45.0 sffm(0 1 10k 5 1k)

N+ and N- are the positive and negative nodes, respectively. Positive current flows from the positive node through the source to the negative node.

DC/TRAN is the source value during a dc or a transient analysis. The value can be omitted if it is zero for both the dc and transient analysis. If the source is time invariant, its value can be prefixed with DC.

ACMAG is amplitude value and ACPHASE is the phase value of the source during an ac analysis. If ACMAG is omitted after the keyword AC, 1 is assumed. If ACPHASE is omitted, 0 is assumed.

DISTOF1 and DISTOF2 are the keywords that specify that the independent source has distortion inputs at the frequencies F1 and F2 respectively (see the description of the distortion analysis parameters). The keywords may be followed by an optional magnitude and phase. The default values of the magnitude and phase are 1.0 and 0.0 respectively.

All independent sources can be assigned time varying values during a transient analysis. If a source is assigned a time varying value, its value at t=0 is used during a DC analysis. There are 5 predefined functions for time varying sources: pulse, exponent, sinusoidal, piece-wise linear, and single frequency FM. If parameters are omitted, the default values shown in the tables below will be assumed. DT and T2 are the increment time and final time in a transient analysis, respectively (see Transient Analysis).

Pulse

General form:

PULSE(I1 I2 TD TR TF PW PER)

Parameters	Default values	Units
I1 (initial value)	None	Amp
I2 (pulsed value)	None	Amp
TD (delay time)	0.0	seconds
TR (rise time)	DT	seconds
TF (fall time)	DT	seconds
PW (pulse width)	T2	seconds
PER (period)	T2	seconds
Example:

IB 3 0 PULSE(1 5 1S 0.1S 0.4S 0.5S 2S)

Sinus

General form:

SIN(I0 IA FREQ TD THETA)

Parameters	Default values	Units
I0 (offset)	None	Amp
IA (amplitude)	None	Amp
FREQ (frequency)	1/T2	Hz
TD (delay)	0.0	seconds
THETA(damping factor)	0.0	1/seconds
The shape of the waveform is:

0 < time < TD

I = I0

TD < time < T2

Example:

IB 3 0 SIN(2 2 5 1S 1)

Exponent

General form:

EXP(I1 I2 TD1 TAU1 TD2 TAU2)

Parameters	Default values	Units
I1 (initial value)	None	Amp
IA (pulsed value)	None	Amp
TD1(rise delay time)	0.0	seconds
TAU1(rise time constant)	DT	seconds
TD2 (delay fall time)	TD1+DT	seconds
TAU2 (fall time constant)	DT	seconds
The shape of the waveform is:

0 < time < TD1

I = I1

TD1 < time < TD2

TD2 < time < T2

Example:

IB 3 0 EXP(1 5 1S 0.2S 2S 0.5S)

Piece-wise Linear

General form:

PWL(T1 I1 <T2 I2 T3 I3 T4 I4 T5 I5 ....>)

Parameters and default values:

Every pair of values (Ti, Ii) specifies that the value of the source is Ii at Ti. The value of the source between these values is calculated using a linear interpolation.

Example:

ICLOCK 7 5 PWL(0 0 1 0 1.2 4 1.6 2.0 2.0 5.0 3.0 1.0)

Single frequency FM

General form:

SFFM(I0 IA FC MDI FS)

Parameters	Default values	Units
I0 (offset)	None	Amp
IA (amplitude)	None	Amp
FC (carrier frequency)	1/T2	Hz
MDI (modulation index)	None	-
FS (signal frequency)	1/T2	Hz
The shape of the waveform is:

Example:

IB 12 0 SFFM(2 1 2 5 0.2)

Supported Analyses

All


J   Junction Field-Effect Transistors (JFETs)

General form:

JXXXXXXX ND NG NS MNAME <AREA> <OFF> <IC=VDS,VGS> <TEMP=T>

Example:

J1 7 2 3 JM1 OFF

ND, NG and NS are the drain, gate and source nodes, respectively. MNAME is the model name, AREA is the area factor, and OFF indicates a optional initial value for the element in a dc analysis. If the area factor is omitted, 1.0 is assumed. The optional initial value IC=VDS,VGS is meant to be used together with UIC in a transient analysis. See the description of the .IC statement for a better way to set transient initial conditions. The optional TEMP value is the temperature at which this device operates. It overrides the temperature specified in the option value.

JFET Model

.MODEL {model name} NJF <model parameters>

.MODEL {model name} PJF <model parameters>

Name	Parameter	Units	Default
VTO	Threshold voltage	V	-2.0
BETA	Transconductance parameter		1.0e-4
LAMBDA	Channel length modulation parameter	1/V	0
RD	Drain resistance	Ω	0
RS	Source resistance	Ω	0
CGS	Zero-bias G-S junction capacitance	F	0
CGD	Zero-bias G-D junction capacitance	F	0
PB	Gate junction potential	V	1
IS	Gate junction saturation current	A	1.0E-14
FC	Coefficient for forward-bias depletion capacitance formula	-	0.5
TNOM	Parameter measurement temperature	°C	27
Temperature Effects

Temperature appears explicitly in the exponential terms.

Temperature dependence of the saturation current in the two gate junctions of the model is determined by:

where Vth is the thermal voltage.

Supported Analyses

All


K   Coupled Inductors (transformers)

General form:

KXXXXXXX LYYYYYYY LZZZZZZZ VALUE

Examples:

k43 laa lbb 0.9999

kxfrmr l1 l2 0.82

LYYYYYYY and LZZZZZZZ are the names of the two coupled inductors, and VALUE is the coupling coefficient K which must be greater than 0 and less than or equal to 1. Using the dot convention, place a dot on the first node of each inductor.

The relation between the coupling coefficient K  and the mutual inductance is given by

,

where Li and Lj are the coupled pair of inductors, and Mij is the mutual inductance between Li and Lj.

Supported Analyses

All


L   Inductors

General form:

LYYYYYYY N+ N- VALUE <IC=Initial values>

Examples:

llink 42 69 1uh

lshunt 23 51 10u ic=15.7ma

N+ and N- are the positive and negative element nodes respectively. VALUE is the inductance in Henries. The optional initial value is the initial time zero value of the inductor current in amps that flows from N+ through the inductor to N-. Notice that the value is used only when the option UIC is specified in a transient analysis.

Supported Analyses

All


M   Metal Oxide Semiconductor Field Effect Transistors (MOSFETs)

General form:

MXXXXXXX ND NG NS NB MNAME <L=VALUE> <W=VALUE> <AD=VALUE>

+ <AS=VALUE> <PD=VALUE> <PS=VALUE> <NRD=VALUE>

+ <NRS=VALUE> <OFF> <IC=VDS,VGS,VBS> <TEMP=T>

Example:

M1 24 2 0 20 TYPE1

m15 15 15 12 32 m w=12.7u  l=207.8u

M1 2 9 3 0 MOD1 L=10U W=5U AD=100P AS=100P PD=40U PS=40U

ND, NG, NS and NB are the drain, gate, source and bulk (substrate) nodes, respectively. MNAME is the model name, L and W are the channel length and width in meters, respectively. AD and AS are the drain and source diffusion areas in square meters. If any of L, W, AD or AS are not specified, default values are used. PD and PS are the perimeters of the drain and source diffusion areas. NRD and NRS are the relative resistivities of the drain and source in number of squares, respectively. Default values of PD and PS are 0.0, while default values of NRD and NRS are 1.0. OFF indicates an optional initial value for the element in a DC analysis. The optional initial value IC=VDS,VGS,VBS is meant to be used together with UIC in a transient analysis. See the description of the .IC statement for a better way to set transient initial conditions. The optional TEMP value is the temperature at which this device operates. It overrides the temperature specified in the option value.

Note! The parameters AD, AS, PD, PS, NRD, NRS, the substrate node and the VBS initial voltage are ignored in Levels 11, 12, 15 and 16.

MOSFET Model

.MODEL {model name} NMOS <model parameters>

.MODEL {model name} PMOS <model parameters>

AIM-Spice supports 16 MOSFET models. The parameter LEVEL selects which model to use. The default is LEVEL=1.

LEVEL=1	Shichman-Hodges

LEVEL=2	Geometric based analytical model

LEVEL=3	Semi-empirical short channel model

LEVEL=4	BSIM1 (Berkeley Short Channel Igfet Model)

LEVEL=5	BSIM2 (as described in [3])

LEVEL=6	MOS6 (as described in [4])

LEVEL=7	An universal extrinsic short channel MOS model (as described in Section 3.9 in [2])

LEVEL=8	An unified long channel MOS model (as described in Section 3.10 and 3.11 in [2])

LEVEL=9	A short channel MOS model (as described in Section 3.10 and 3.11 in [2])

LEVEL=10	An unified intrinsic short channel model (as described in Section 3.10 and 3.11 in [2])

LEVEL=11	An unified extrinsic amorphous silicon thin film transistor model (as described in Section 5.2 in [2])

LEVEL=12	A model for polysilicon thin film transistors (as described in Section 5.3 in [2])

LEVEL=14	BSIM3 [5]

LEVEL=15	ASIA2, amorphous-Si TFT model

LEVEL=16	PSIA2, poly-Si TFT model

Effects of charge storage based on the model by Meyer is implemented in Levels 1, 2, 3, 6, 7, 8, 9, 10, 11, 12, 15 and 16. In the universal MOSFET model (Level 7), a second, unified charge storage model based on the charge conserving Meyer-like approach proposed by Turchetti et al. [6] is implemented.  The BSIM models (Levels 4, 5, and 14) use charge based models owing to Ward and Dutton [7].

Effects of the thin-oxide capacitance is treated slightly different in Level 1. Voltage dependent capacitances are included only if TOX is specified.

A redundancy exists in specifying junction parameters. For example, the reverse current can be specified either with the IS parameter (in Amp) or with JS (in Amp/m2). The first choice is an absolute value while the second choice is multiplied with AD and AS to give the reverse current at the drain and source junctions, respectively. The latter approach is preferred. The same is also true for the parameters CBD, CBS and CJ. Parasitic resistances can be given with RD and RS (in ohms) or with RSH (in ohms/square). RSH is multiplied with number of squares NRD and NRS.

Parameters for Levels 1, 2, 3 and 6:

Name	Parameter	Units	Default
VTO	Zero-bias threshold voltage	V	0.0
KP	Transconductance parameter		2.0e-5
GAMMA	Bulk threshold parameter		0.0
PHI	Surface potential	V	0.6
LAMBDA	Channel length modulation (only Levels 1 and 2)	1/V	0.0
RD	Drain resistance	Ω	0.0
RS	Source resistance	Ω	0.0
CBD	Zero-bias B-D junction capacitance	F	0.0
CBS	Zero-bias B-S junction capacitance	F	0.0
IS	Bulk junction saturation current	A	1.0e-14
PB	Bulk junction potential	V	0.8
CGSO	Gate-source overlap capacitance per meter channel width	F/m	0.0
CGDO	Gate-drain overlap capacitance per meter channel width	F/m	0.0
CGBO	Gate-bulk overlap capacitance per meter channel width	F/m	0.0
RSH	Drain and source diffusion sheet resistance	Ω /	0.0
CJ	Zero-bias bulk junction bottom capacitance per square-meter of junction area		0.0
MJ	Bulk junction bottom grading coefficient	-	0.5
CJSW	Zero-bias bulk junction sidewall capacitance per meter of junction perimeter	F/m	0.0
MJSW	Bulk junction sidewall grading coefficient	-	0.50 (level 1) 0.33 (level 2)
JS	Bulk junction saturation current per m2 of junction area		0
TOX	Gate oxide thickness	m	1.0e-7
NSUB	Substrate doping		0.0
NSS	Surface state density		0.0
NFS	Fast surface state density		0.0
TPG	Type of gate material: +1 : opposite of substrate  -1 : same as substrate  0 : Al gate	-	1.0
XJ	Metallurgical junction depth	m	0.0
LD	Lateral diffusion	m	0.0
U0	Surface mobility		600
UCRIT	Critical field for mobility degradation (only Level 2)	V/cm	1.0e4
UEXP	Critical field exponent in mobility degradation (only Level 2)	-	0.0
UTRA	Transverse field coefficient (deleted for Level 2)	-	0.0
VMAX	Maximum drift velocity for carriers	m/s	0.0
NEFF	Total channel charge (fixed and mobile) coefficient (only Level 2)	-	1.0
KF	Flicker noise coefficient	-	0.0
AF	Flicker noise exponent	-	1.0
FC	Coefficient for forward-bias depletion capacitance formula	-	0.5
DELTA	Width effect on threshold voltage (only Levels 2 and 3)	-	0.0
THETA	Mobility modulation (only Level 3)	1/V	0.0
ETA	Static feedback (only Level 3)	-	0.0
KAPPA	Saturation field factor (only Level 3)	-	0.2
TNOM	Parameter measurement temperature	°C	27
MOSFET Levels 4, 5 and 14 are the BSIM models (Berkeley Short Channel IGFET Model). Parameters for these models are obtained from process characterization.

Parameters marked with an '*'  in the l/w column in the tables below have length and width dependency (only Levels 4 and 5). For example, for the flat band voltage, VFB, the dependence on the gate electrode geometry can be expressed in terms of the additional flat band parameters, LVFB and WVFB, measured in Volt·μm:

where

Note that BSIM models are meant to be used together with a process characterization system. None of the parameters in these models have default values, and leaving one out is registered as an error (except for BSIM3 which has default values).

AIM-Spice model parameters common for Levels 4 and 5 are listed below.

Name	Parameter	Units	l/w
TOX	Gate oxide thickness	μm
VFB	Flat band voltage	V
PHI	Surface inversion potential	V	*
K1	Body effect coefficient		*
K2	Drain/source depletion charge sharing coefficient	-	*
DL	Shortening of channel	μm
DW	Narrowing of channel	μm
N0	Zero-bias subthreshold slope coefficient	-	*
NB	Sensitivity of subthreshold slope to substrate bias	-	*
ND	Sensitivity of subthreshold slope to drain bias	-	*
TEMP	Temperature at which parameters were measured	C
VDD	Measurement bias range	V
CGDO	Gate-drain overlap capacitance per meter channel width	F/m
CGSO	Gate-source overlap capacitance per meter channel width	F/m
CGBO	Gate-bulk overlap capacitance per meter channel width	F/m
XPART	Gate-oxide capacitance charge model flag	-
RSH	Drain and source diffusion sheet resistance	Ω/
JS	Source drain junction current density
PB	Built in potential of source drain junction	V
MJ	Grading coefficient of source drain junction	-
PBSW	Built in potential of source drain junction sidewall	V
MJSW	Grading coefficient of source drain junction sidewall	-
CJ	Source drain junction capacitance per unit area
CJSW	Source drain junction sidewall capacitance per unit length	F/m
WDF	Source drain junction default width	m
DELL	Source drain junction length reduction	m

XPART=0 selects a 40/60 drain/source partition of the gate charge in saturation, while XPART=1 selects a 0/100 drain/source charge partition.

BSIM1 (Level 4) parameters:

Name	Parameter	Units	l/w
ETA	Zero-bias drain-induced barrier lowering coefficient	-	*
MUZ	Zero-bias mobility
U0	Zero-bias transverse-field mobility degradation coefficient		*
U1	Zero-bias velocity saturation coefficient	μm/V	*
X2MZ	Sens. of mobility to substrate bias at Vds=0		*
X2E	Sens. of drain-induced barrier lowering effect to substrate bias		*
X3E	Sens. of drain-induced barrier lowering effect to drain bias at  Vds=  Vdd		*
X2U0	Sens. of transverse field mobility degradation effect to substrate bias	1/V2	*
X2U1	Sens. of velocity saturation effect to substrate bias		*
MUS	Mobility at zero substrate bias and at Vds=  Vdd
X2MS	Sens. of mobility to substrate bias at Vds=  Vdd		*
X3MS	Sens. of mobility to drain bias at Vds=  Vdd		*
X3U1	Sens. of velocity saturation effect on drain bias at Vds=  Vdd		*
	Common parameters for level 4 and 5
BSIM2 (Level 5) parameters:

Name	Parameter	Units	l/w
ETA0	Vds dependence of threshold voltage at Vds = 0 V	-	*
ETAB	Vbs dependence of ETA	1/V	*
MU0	Low-field mobility at Vds  = 0, Vgs = Vth
MU0B	Vbs dependence of low-field mobility		*
MUS0	Mobility at Vds = Vdd, Vgs = Vth		*
MUSB	Vbs dependence of MUS0		*
MU20	Vds dependence of mobility in tanh term	−	∗
MU2B	Vbs dependence of MU2	1/V	*
MU2G	Vgs dependence of MU2	1/V	*
MU30	Vds dependence of mobility in linear term		*
MU3B	Vbs dependence of MU3		*
MU3G	Vgs dependence of MU3		*
MU40	Vds dependence of mobility in linear term		*
MU4B	Vbs dependence of MU4		*
MU4G	Vgs dependence of MU4		*
UA0	Linear Vgs dependence of mobility	1/V	*
UAB	Vbs dependence of UA		*
UB0	Quadratic Vgs dependence on mobility		*
UBB	Vbs dependence on UB		*
U10	Vds dependence on mobility	1/V	*
U1B	Vbs dependence on U1		*
U1D	Vds dependence on U1		*
VOF0	Threshold voltage offset at Vds = 0, Vbs = 0	−	∗
VOFD	Vds dependence on VOF	1/V	*
AI0	Pre-factor of hot-electron effect	−	∗
AIB	Vbs dependence on AI	1/V	*
BI0	Exponential factor of hot-electron effect	V	*
BIB	Vbs dependence on BI	−	∗
VGHIGH	Upper bound of the cubic spline function	V	*
VGLOW	Lower bound of the cubic spline function	V	*
VGG	Maximum Vgs	V
VBB	Maximum Vbs	V
	Common parameters for level 4 and 5
BSIM3 version 3.1 (Level 14) parameters:

Name	Parameter	Units	Default

Control Parameters

CAPMOD	Flag for the short channel capacitance model	-	2
MOBMOD	Mobility model selector	-	1
NQSMOD	NQS model selector	-	0
NOIMOD	Noise model selector	-	1

DC Parameters

VTH0	Threshold voltage at zero substrate bias	V	0.7 (NMOS) -0.7 (PMOS)
K1	First-order body effect coefficient		0.5
K2	Second-order body effect coefficient	-	-0.0186
K3	Narrow width effect coefficient	-	80
K3B	Body effect coefficient of K3	-	0
W0	Narrow width effect reference width	m	2.5E-6
NLX	Lateral non-uniform doping coefficient	m	1.74E-7
VBM	Maximum substrate bias	V	-3
DVT0	First coefficient of short-channel effect on Vth	-	2.2
DVT1	Second coefficient of short-channel effect on Vth	-	0.53
DVT2	Body-bias coefficient of short-channel effect on Vth	1/V	-0.032
DVT0W	First coefficient of narrow width effect on Vth at small L	1/m	0
DVT1W	Second coefficient of narrow width effect on Vth at small L	1/m	5.3E6
DVT2W	Body-bias coefficient of short-channel effect on Vth at small L	1/V	-0.032
U0	Low-field mobility at TNOM		670 (NMOS) 250 (PMOS)
UA	First-order mobility degradation coefficient	m/V	2.25E-9
UB	Second-order mobility degradation coefficient		5.87E-19
UC	Body-effect of mobility degradation coefficient	1/V	*
VSAT	Saturation velocity at TNOM	cm/s	8.0E6
A0	Bulk charge effect coefficient for channel length	-	1.0
AGS	Gate bias coefficient of the Abulk	1/V	0
B0	Bulk charge effect coefficient for channel width	m	0
B1	Bulk charge effect width offset	m	0
KETA	Body bias coefficient of the bulk charge effect	1/V	-0.047
A1	First non-saturation effect coefficient	1/V	0
A2	Second non-saturation effect coefficient	-	1.0
RDSW	Width coefficient of parasitic resistance		0
PRWG	Gate bias effect coefficient of RDSW	1/V	0
PRWB	Body effect coefficient of RDSW		0
WR	Width offset from Weff for Rds calculation	-	1
WINT	Width offset fitting parameter from I-V without bias	m	0
LINT	Length offset fitting parameter from I-V without bias	m	0
DWG	Coefficient of Weffs gate dependence	m/V	0
DWB	Coefficient of Weffs body bias dependence		0
VOFF	Offset voltage in the subthreshold region at large W and L	V	-0.11
NFACTOR	Subthreshold swing factor	-	1
ETA0	Subthreshold region DIBL coefficient	-	0.08
ETAB	Body bias coefficient for the subthreshold DIBL effect	1/V	-0.07
DSUB	Subthreshold DIBL coefficient exponent	-	DROUT
CIT	Interface trapped charge capacitance		0
CDSC	Drain/Source to channel coupling capacitance		2.4E-4
CDSCB	Body-bias sensitivity of CDSC		0
CDSCD	Drain-bias sensitivity of CDSC		0
PCLM	Channel length modulation parameter	-	1.3
PDIBLC1	First output resistance DIBL effect correction parameter	-	0.39
PDIBLC2	Second output resistance DIBL effect correction parameter	-	0.0086
PDIBLCB	Body effect coefficient of DIBL correction parameters	1/V	0
DROUT	L dependence coefficient of DIBL correction parameters	-	0.56
PSCBE1	First substrate current body-effect parameter	V/m	4.24E8
PSCBE2	Second substrate current body-effect parameter	m/V	1.0E-5
PVAG	Gate voltage dependence of Rout coefficient	-	0
DELTA	Effective Vds parameter		0.01
NGATE	Poly gate doping concentration		0
ALPHA0	First impact ionization current parameter	m/V	0
BETA0	Second impact ionization current parameter	V	30
RSH	Source/Drain sheet resistance in ohms per square	Ω/	0
JSSW	Side wall saturation current density	A/m	0
JS	Source/Drain junction saturation current density		1E-4

AC and Capacitance Parameters

XPART	Charge partitioning rate flag	-	0
CGS0	Non-LDD region source-gate overlap capacitance per meter channel length	F/m	Calculated
CGD0	Non-LDD region drain-gate overlap capacitance per meter channel length	F/m	Calculated
CGB0	Gate-bulk overlap capacitance per meter channel length	F/m	2*DWC*Cox
CJ	Source and drain junction capacitance per unit area		5E4
MJ	Grading coefficient of source drain junction	-	0.5
MJSW	Grading coefficient of source drain junction sidewall	-	0.33
CJSW	Source drain junction sidewall capacitance per unit length	F/m	5E-10
CJSWG	Source/drain gate sidewall junction capacitance garding coefficient	F/m	CJSW
MJSWG	Source/drain gate sidewall junction capacitance coefficient	-	MJSW
PBSW	Source/drain side junction built-in potential	V	1.0
PB	Bottom built-in potential	V	1.0
PBSWG	Source/drain gate sidewall junction built-in potential	V	PBSW
CGS1	Overlap capacitance of lightly doped source-gate region	F/m	0
CGD1	Overlap capacitance of lightly doped drain-gate region	F/m	0
CKAPPA	Coefficient for lightly doped region overlap capacitance fringing field capacitance	F/m	0.6
CF	Fringing field capacitance	F/m	Calculated
CLC	Constant term for the short channel model	m	0.1E-6
CLE	Exponential term for the short channel model	-	0.6
DLC	Length offset fitting parameter from C-V	m	LINT
DWC	Width offset fitting parameter from C-V	m	WINT
VFB	Flat-band voltage parameter (for capmmod=0 only)	V	-1

Temperature Effect Parameters

TNOM	Temperature at which parameters are extracted	°C	27
PRT	Temperature coefficient for RDSW		0
UTE	Temperature coefficient of mobility	-	-1.5
KT1	Threshold voltage temperature coefficient	V	-0.11
KT1L	Channel length sensitivity of temperature coefficient for threshold voltage	V·m	0
KT2	Body-bias coefficient of the Vth temperature effect	-	0.022
UA1	Temperature coefficient of UA	m/V	4.31E-9
UB1	Temperature coefficient of UB		-7.61E-18
UC1	Temperature coefficient of UC	1/V	-0.056
AT	Temperature coefficient of VSAT	m/s	3.3E4
NJ	Emission coefficient of junction	-	1
XTI	Junction current temperature exponent coefficient	-	3

NQS Model Parameters

ELM	Elmore constant of the channel	-	5

dW and dL Parameters

WL	Coefficient of length dependence for width offset		0.0
WLN	Power of length dependence of width offset	-	1.0
WW	Coefficient of width dependence for width offset		0.0
WWN	Power of width dependence of width offset	-	1.0
WWL	Coefficient of length and width cross term for width offset		0.0
L1	Coefficient of length dependence for length offset		0.0
L1N	Power of length dependence for length offset	-	1.0
LW	Coefficient of width dependence for length offset		0.0
LWN	Power of width dependence for length offset	-	1.0
LWL	Coefficient of length and width cross term for length offset		0.0

Bin Description Parameters

LMIN	Minimum channel length	m	0
LMAX	Maximum channel length	m	1
WMIN	Minimum channel width	m	0
WMAX	Maximum channel width	m	1
BINUNIT	Bin unit scale factor	-	1

Process Parameters

TOX	Gate oxide thickness	m	150 Å
XJ	Metallurgical junction depth	m	0.15 μm
GAMMA1	Body effect coefficient near the interface		Calculated
GAMMA2	Body effect coefficient in the bulk		Calculated
NCH	Channel doping concentration		1.7E17
NSUB	Doping concentration		6E16
VBX	Vbs at which the depletion width equals XT	V	Calculated
XT	Doping depth	m	1.55E-7

Noise Model Parameters

NOIA	Noise parameter A	-	1E20 (NMOS) 9.9E18 (PMOS)
NOIB	Noise parameter B	-	5E4 (NMOS) 2.4E3 (PMOS)
NOIC	Noise parameter C	-	-1.4E-12 (NMOS) 1.4E-12 (PMOS)
EM	Saturated field	V/m	4.1E7
AF	Frequency exponent	-	1
EF	Flicker exponent	-	1
KF	Flicker noise parameter	-	0
* If MOBMOD = 1 or 2: UC = -4.65E-11. If MOBMOD = 3: UC = -0.046

For a detailed BSIM3 model reference, download the BSIM3v3 manual. The URL address is: http://rely.eecs.berkeley.edu:8080/bsim3www/bsim3.html.

AIM-Spice model parameters common for Levels 7, 8, 9, and 10 are:

Name	Parameter	Units	Default
VTO	Zero-bias threshold voltage	V	0.0
PHI	Surface potential	V	0.6
RD	Drain resistance	Ω	0.0
RS	Source resistance	Ω	0.0
CBD	Zero-bias B-D junction capacitance	F	0.0
CBS	Zero-bias B-S junction capacitance	F	0.0
IS	Bulk junction saturation current	A	1.0e-14
PB	Bulk junction potential	V	0.8
CGSO	Gate-source overlap capacitance per meter channel width	F/m	0.0
CGDO	Gate-drain overlap capacitance per meter channel width	F/m	0.0
CGBO	Gate-bulk overlap capacitance per meter channel width	F/m	0.0
RSH	Drain and source diffusion sheet resistance	Ω /	0.0
CJ	Zero-bias bulk junction bottom capacitance per square-meter of junction area		0.0
MJ	Bulk junction bottom grading coefficient	-	0.5
CJSW	Zero-bias bulk junction sidewall capacitance per meter of junction perimeter	F/m	0.0
MJSW	Bulk junction sidewall grading coefficient	-	0.33
JS	Bulk junction saturation current per m2 of junction area		0
TOX	Gate oxide thickness	m	1.0e-7
NSUB	Substrate doping		0.0
NSS	Surface state density		0.0
TPG	Type of gate material: +1 : opposite of substrate  -1 : same as substrate  0 : Al gate	-	1.0
XJ	Metallurgical junction depth	m	0.0
LD	Lateral diffusion	m	0.0
U0	Surface mobility		280 (level 7) 625 (others, nmos) 279 (others, pmos)
VMAX	Maximum drift velocity for carriers	m/s	4.0e4 (level 7) 6.0e4 (level 8) 7.8e4 (level 9) 8.6e4 (level 10)
KF	Flicker noise coefficient	-	0.0
AF	Flicker noise exponent	-	1.0
FC	Coefficient for forward-bias depletion capacitance formula	-	0.5
TNOM	Parameter measurement temperature	°C	27
AIM-Spice model parameters specific for threshold voltage calculation in Levels 8, 9 and 10:

Name	Parameter	Units	Default
GAMMA	Bulk threshold parameter		0.0
DELTA	Width effect on threshold voltage	-	0.0
The following parameters are used for the threshold voltage model of AIM-Spice MOSFET Level 7:

Name	Parameter	Units	Default
GAMMAS0	Body effect constant in front of square root term		0.0
LGAMMAS	Sensitivity of γS on device length		0.0
WGAMMAS	Sensitivity of γS on device width		0.0
GAMMAL0	Body effect constant in front of linear term	-	0.0
LGAMMAL	Sensitivity of γL on device length	-	0.0
WGAMMAL	Sensitivity of γL on device width	-	0.0
L0	Gate length of nominal device	m	2μm
W0	Gate width of nominal device	m	20μm
The following are the expressions for the threshold voltage:

,

where

,

.

The value of VT00 above is given by the model parameter VTO as

.

These equations are valid for

.

Beyond this limit, we assume that the threshold voltage remains constant at

.

Other parameters specific for Level 7 are:

Name	Parameter	Units	Default (NMOS)
LAMBDA	Output conductance parameter	1/V	0.048
ETA	Subthreshold ideality factor	-	1.32
M	Knee shape parameter	-	4.0
DELTA	Transition width parameter	-	5.0
THETA	Mobility degradation parameter	m/V	0
SIGMA0	DIBL parameter	-	0.048
VSIGMAT	DIBL parameter	V	1.7
VSIGMA	DIBL parameter	V	0.2
RDI	Internal drain resistance	Ω	0
RSI	Internal source resistance	Ω	0
CV	Charge storage model selector	−	1
CVE	Meyer-like capacitor model selector	−	1
FPE	Charge partitioning scheme selector	−	1
XQC	Charge partitioning factor	−	0.6
MCV	Transition width parameter used by the charge partitioning scheme	−	10
ALPHA	Parameter accounting for the threshold dependence on the channel potential	−	1.05
VFB	Flat band voltage	V	*
	Common parameters for level 7, 8, 9 and 10
* Parameter is calculated if not specified

Modeling of charge storage for the Level 7 model is selected by specifying a value for the model parameter CV. CV = 1 selects the standard Meyer model and CV = 2 selects the charge conserving Meyer-like model.

Allowed values of the Meyer-like capacitor model selector CVE are 1 and 2. CVE = 1 selects the standard Meyer capacitors and CV = 2 selects the UCCM capacitors.

The model parameter FPE selects the charge partitioning scheme used by the Meyer-like charge storage model (CV = 2). FPE = 1 selects a constant partitioning factor, FPE = 2 selects an empirical partitioning scheme, and FPE=3 selects an analytical partitioning scheme.

Either intrinsic or extrinsic models can be selected by proper use of the parameters RD, RS, RDI, and RSI. If values for RD and RS are specified, the intrinsic model is selected with parasitic resistances applied externally. The extrinsic model is selected by specifying values for RDI and RSI.

Parameters specific for Level 8 are:

Name	Parameter	Units	Default
ALPHA	Parameter accounting for the threshold dependence on the channel potential	-	1.164 (NMOS) 1.4 (PMOS)
K1	Mobility parameter		28 (NMOS) 1510 (PMOS)
ETA	Subthreshold ideality factor	-	1.3 (NMOS) 1.2 (PMOS)
	Common parameters for level 7, 8, 9 and 10
Parameters specific for Level 9 are:

Name	Parameter	Units	Default
ALPHA	Parameter accounting for the threshold dependence on the channel potential	-	1.2 (NMOS) 1.34 (PMOS)
XI	Saturation voltage parameter (NMOS only)	-	0.79
GAM	Saturation point parameter	-	3.0 (NMOS) 2.35 (PMOS)
K1	Mobility parameter		28 (NMOS) 1510 (PMOS)
LAMBDA	Characteristic length of the saturated region of the channel	m	994Å (NMOS) 1043Å (PMOS)
ZETA	Velocity saturation factor (PMOS only)	-	0.34
	Common parameters for level 7, 8, 9 and 10
Parameters specific for Level 10 are:

Name	Parameter	Units	Default
ALPHA	Bulk charge factor	-	1.05 (NMOS) 1.3 (PMOS)
ETA	Ideality factor in subthreshold	-	1.42 (NMOS) 1.39 (PMOS)
SIGMA	Parameter accounting for DIBL effects	-	0.03 (NMOS) 0.007 (PMOS)
K1	Mobility parameter		28 (NMOS) 1510 (PMOS)
LAMBDA	Channel length modulation parameter	m	8.58E-8 (NMOS) 7.25E-8 (PMOS)
XI	Saturation voltage factor (NMOS only)	-	0.76
ZETA	Velocity saturation factor (PMOS only)	-	0.28
GAM	Saturation point parameter (PMOS only)	-	2.35
	Common parameters for level 7, 8, 9 and 10
Model parameters common to Level 11, 12, 15 and 16 are:

Name	Parameter	Units	Default
VTO	Zero-bias threshold voltage	V	0.0
RD	Drain resistance	Ω	0.0
RS	Source resistance	Ω	0.0
CGSO	Gate-source overlap capacitance per meter channel width	F/m	0.0
CGDO	Gate-drain overlap capacitance per meter channel width	F/m	0.0
TOX	Thin-oxide thickness	m	1.0e-7
U0	Surface mobility (only level 11 and 12)		1.0 (level 11) 100 (level 12)
ETA	Subthreshold slope (not level 15)	-	6.9
TNOM	Parameter measurement temperature	°C	27
Parameters specific for Level 11 are:

Name	Parameter	Units	Default
EPS	Relative dielectric constant of substrate	-	11.7
EPSI	Relative dielectric constant of gate insulator	-	3.9
LAMBDA	Output conductance parameter	1/V	0.0048
M1	Knee shape parameter	-	2.5
M2	Exponent in mobility expressions	-	0.5
MC	Exponent in capacitance expressions	-	3.0
N0	Scaling factor		1E16
SIGMA0	Parameter accounting for DIBL effects	-	0.048
V2	Characteristic voltage	V	0.086
VSIGMA	Parameter accounting for DIBL effects	V	0.2
VSIGMAT	Parameter accounting for DIBL effects	V	1.7
XO	Fitting parameter	V/J	3.63E20
	Common parameters for level 11, 12, 15 and 16
Parameters specific for Level 12 are:

Name	Parameter	Units	Default
V0	Scaling voltage	V	10.7
GAMMA	Saturation voltage parameter	-	0.03
RSH	Drain and source diffusion sheet resistance	Ω /	0.0
	Common parameters for level 11, 12, 15 and 16
Parameters specific for Level 15 are:

Name	Parameter	Units	Default
ALPHASAT	Saturation modulation parameter	-	0.6
DEF0	Dark Fermi level position	eV	0.6
DELTA	Transition width parameter	-	5
EL	Activation energy of the hole leakage current	eV	0.35
EMU	Field effect mobility activation energy	eV	0.06
EPS	Relative dielectric constant of substrate	-	11
EPSI	Relative dielectric constant of gate insulator	-	7.4
GAMMA	Power law mobility parameter	-	0.4
GMIN	Minimum density of deep states		1E23
IOL	Zero bias leakage current	A	3E-14
KASAT	Temperature coefficient of ALPHASAT	1/°C	0.006
KVT	Threshold voltage temperature coefficient	V/°C	-0.036
LAMBDA	Output conductance parameter	1/V	0.0008
M	Knee shape parameter	-	2.5
MUBAND	Conduction band mobility		0.001
SIGMA0	Minimum leakage current parameter	A	1E-14
V0	Characteristic voltage for deep states	V	0.12
VAA	Characteristic voltage for field effect mobility (determined by tail states)	V	7.5E3
VDSL	Hole leakage current drain voltage parameter	V	7
VFB	Flat band voltage	V	-3
VGSL	Hole leakage current gate voltage parameter	V	7
VMIN	Convergence parameter	V	0.3
	Common parameters for level 11, 12, 15 and 16
Equivalent circuit

Drain current equations

Temperature dependence

Capacitance equations

Parameters specific for Level 16 are:

Name	Parameter	Units	Default
ASAT	Proportionality constant of Vsat	-	1
AT	DIBL parameter 1	m/V	3E-8
BLK	Leakage barrier lowering constant	-	0.001
BT	DIBL parameter 2	m·V	1.9E-6
DASAT	Temperature coefficient of ASAT	1/°C	0
DD	Vds field constant	m	1400 Å
DELTA	Transition width parameter	-	4.0
DG	Vgs field constant	m	2000 Å
DMU1	Temperature coefficient of MU1		0
DVT	The difference between VON and the threshold voltage	V	0
DVTO	Temperature coefficient of VTO	V/°C	0
EB	Barrier height of diode	EV	0.68
ETA	Subthreshold ideality factor	-	7
ETAC0	Capacitance subthreshold ideality factor at zero drain bias	-	ETA
ETAC00	Capacitance subthreshold coefficient of drain bias	1/V	0
I0	Leakage scaling constant	A/m	6.0
I00	Reverse diode saturation current	A/m	150
LASAT	Coefficient for length dependence of ASAT	M	0
LKINK	Kink effect constant	M	19E-6
MC	Capacitance knee shape parameter	-	3.0
MK	Kink effect exponent	-	1.3
MMU	Low field mobility exponent	-	3.0
MU0	High field mobility		100
MU1	Low field mobility parameter		0.0022
MUS	Subthreshold mobility		1.0
RDX	Resistance in series with Cgd	Ω	0
RSX	Resistance in series with Cgs	Ω	0
VFB	Flat band voltage	V	-0.1
VKINK	Kink effect voltage	V	9.1
VON	On-voltage	V	0
	Common parameters for level 11, 12, 15 and 16
Equivalent circuit

Drain current equations

The expression for the subthreshold current is given by:

where εi is the dielectric constant of the oxide and kB is the Boltzmanns constant.

Above threshold (VGT > 0), the conduction current is given by:

Subthreshold leakage current is the result of thermionic field emission of carriers through the grain boundary trap states and is described by:

Finally, for very large drain biases, the kink effect is observed. It is modeled as impact ionization in a narrow region near the drain.  The expression can be written as:

,

The impact ionization current, Ikink, is added to the drain current.

Threshold voltage

If VTO is not specified

else

Temperature dependence

Capacitance equations

,

Temperature Effects (for all MOSFET levels)

Temperature appears explicitly in the exponential terms in the equations describing current across the bulk junctions.

Temperature appears explicitly in the value of junction potential, φ (in AIM-Spice PHI). The temperature dependence is given by:

where k is Boltzmann's constant, q is the electronic charge, Na is the acceptor impurity density, Nd is the donor impurity density, and Ni is the intrinsic carrier concentration.

Temperature appears explicitly in the value of surface mobility μ0 (or U0). The temperature dependence is given by:

Supported Analyses

Level 1-3:	All

Level 4:	Noise Analysis not supported

Level 5:	Distortion and Noise Analysis not supported

Level 6:	AC, Distortion, Noise, and Pole-Zero Analysis not supported

Level 7-13:	Distortion and Noise Analysis not supported

Level 14:	Distortion Analysis not supported

Level 15,16:	Distortion, Noise and Pole-Zero analyses not supported


N   Heterojunction Bipolar Transistors (HBTs)

General form:

NXXXXXXX NC NB NE <NS> MNAME <AREA> <OFF> <IC=VBE,VCE>

+ <TEMP=T>

Example:

N23 10 24 13 NMOD IC=0.6,5.0

n2 5 4 0 nnd

NC, NB and NE are the collector, base and emitter nodes, respectively. NS is the substrate node. If this is not given, ground is assumed. MNAME is the model name, AREA is the area factor, and OFF indicates an optional initial value for the element in a DC analysis. If the area factor is omitted, 1.0 is assumed. The optional initial value IC=VBE,VCE is meant to be used together with UIC in a transient analysis. See the description of the .IC statement for a better way to set transient initial conditions. The optional TEMP value is the temperature at which this device operates. It overrides the temperature specified in the option value.

HBT Model

.MODEL {model name} HNPN <model parameters>

.MODEL {model name} HPNP <model parameters>

The heterojunction bipolar transistor model in AIM-Spice is a modification of the Ebers-Moll bipolar transistor model.

Name	Parameter	Units	Default
IS	Transport saturation current	A	1e-16
BF	Ideal maximum forward beta	-	100
NF	Forward current emission coefficient	-	1.0
ISE	B-E leakage saturation current	A	0
NE	B-E leakage emission coefficient	-	1.2
BR	Ideal maximum reverse beta	-	1
NR	Reverse current emission coefficient	-	1
ISC	B-C leakage saturation current	A	0
NC	B-C leakage emission coefficient	-	2
RB	Base resistance	Ω	0
RE	Emitter resistance	Ω	0
RC	Collector resistance	Ω	0
CJE	B-E zero bias depletion capacitance	F	0
VJE	B-E built-in potential	V	0.75
MJE	B-E junction exponential factor	-	0.33
TF	Ideal forward transit time	s	0
XTF	Coefficient for bias dependence of TF	-	0
VTF	Voltage describing VBC dependence of TF	V	infinite
ITF	High current parameter for effect on TF	A	0
PTF	Excess phase at f=1.0/(TF · 2π) Hz	Deg
CJC	B-C zero bias depletion capacitance	F	0
VJC	B-C built-in potential	Volt	0.75
MJC	B-C junction exponential factor	-	0.33
XCJC	Fraction of B-C depletion capacitance connected to internal base node.	-	1
TR	Ideal reverse transit-time	s	0
CJS	zero-bias collector-substrate capacitance	F	0
VJS	Substrate junction built-in potential	V	0.75
MJS	Substrate junction exponential factor	-	0
XTB	Forward and reverse beta temperature exponent	-	0
EG	Energy gap for temperature effect on IS	eV	1.11 (Si)
XTI	Temperature exponent for effect on IS	-	3
KF	Flicker-noise coefficient	-	0
AF	Flicker-noise exponent	-	1
FC	Coefficient for forward-bias depletion capacitance formula	-	0.5
TNOM	Parameter measurement temperature	°C	27
IRB0	Base region recombination saturation current	A	0
IRS1	Surface recombination saturation current 1	A	0
IRS2	Surface recombination saturation current 2	A	0
ICSAT	Collector saturation current	A	0
M	Knee shape parameter	-	3
The modification to the Ebers-Moll model consists of two new contributions to the generation/recombination current and a limitation on the intrinsic collector current.

Recombination in the base region is modeled by the expression

Surface recombination is modeled by the expression.

where IRS1 and IRS2 are proportional to the emitter perimeter.

If the model parameters M and ICSAT are given, the intrinsic collector current is modified according to the following expression:

Supported Analyses

Distortion, Noise, and Pole-Zero Analysis not supported.


O   Lossy Transmission Lines  (LTRA)

General form:

OXXXXXXX N1 N2 N3 N4 MNAME

Example:

o23 1 0 2 0 lmod

ocon 10 5 20 5 interconnect

This is a two-port convolution model for single-conductor lossy transmission lines. N1 and N2 are the nodes at port 1, N3 and N4 are the nodes at port 2. It is worth mentioning that a lossy transmission line with zero loss may be more accurate than the lossless transmission line.

LTRA Model

.MODEL {model name} LTRA <model parameters>

The uniform RLC/RC/LC/RG transmission line model (LTRA) models a uniform constant-parameter distributed transmission line. In case of RC and LC, the URC and TRA models may also be used. However, the newer LTRA model is usually faster and more accurate. The operation of the LTRA model is based on the convolution of the transmission line's impulse response with its inputs see [8].

The LTRA model parameters are as follows:

Name	Parameter	Units	Default
R	Resistance/Length	Ω/m	0.0
L	Inductance/Length	H/m	0.0
C	Capacitance/Length	F/m	0.0
G	Conductance/Length	1/Ωm	0.0
LEN	Length of line	m	-
REL	Breakpoint control	-	1
ABS	Breakpoint control	-	1
NOSTEPLIMIT	Don't limit timestep to less than line delay	Flag	not set
NOCONTROL	Don't do complex timestep control	Flag	not set
LININTERP	Use linear interpolation	Flag	not set
MIXEDINTERP	Use linear when quadratic seems bad	Flag	not set
COMPACTREL	Special RELTOL for history compaction		RELTOL
COMPACTABS	Special ABSTOL for history compaction		ABSTOL
TRUNCNR	Use Newton-Raphson method for timestep control	Flag	not set
TRUNCDONTCUT	Don't limit timestep to keep impulse-response errors low	Flag	not set
The types of lines implemented so far are : uniform transmission line with series loss only (RLC) , uniform RC line (RC), lossless transmission line (LC), and distributed series resistance and parallel conductance only (RG). Any other combination will yield erroneous results and should be avoided. The length (LEN) of the line must be specified.

Here follows a detailed description on some of the model parameters:

NOSTEPLIMIT is a flag that will remove the default restrictions of limiting time-step to less than the line delay in the RLC case.

NOCONTROL is a flag that prevents the default limitation on the time-step based on convolution error criteria in the RLC and RC cases.  This speeds up the simulation, but may in some cases reduce the accuracy.

LININTERP is a flag that, when set, will use linear interpolation instead of the default quadratic interpolation for calculating delayed signals.

MIXEDINTERP is a flag that, when set, uses a metric for judging whether quadratic interpolation is applicable, and if not so, uses linear interpolation. Otherwise it uses the default quadratic interpolation.

TRUNCDONTCUT is a flag that removes the default cutting of the time-step to limit errors in the actual calculation of impulse-response related quantities.

COMPACTREL and COMPACTABS are quantities that control the compacting of the past history of values stored for convolution.  Large values of these parameters result in lower accuracy but usually increase the simulation speed.  These are to be used with the TRYTOCOMPACT option.

TRUNCNR is a flag that turns on the use of Newton-Raphson iterations to determine an appropriate timestep in the timestep control routines. The default is a trial and error procedure by cutting the previous timestep in half.

If you want to increase the speed of the simulation, follow these guidelines:

The most efficient option for increasing the speed of the simulation is REL.  The default value of 1 is usually safe from the point of view of accuracy, but occasionally increases the computation time.  A value greater than 2 eliminates all breakpoints and may be worth trying depending on the nature of the rest of the circuit, keeping in mind that it may not be safe from the point of view of accuracy.  Breakpoints can usually be entirely eliminated if the circuit is not expected to have sharp discontinuities.  Values between 0 and 1 are usually not needed, but may be used for setting a large number of breakpoints.

It is also possible to experiment with COMPACTREL when the option TRYTOCOMPACT is specified.  The legal range is between 0 and 1.  Larger values usually decrease the accuracy of the simulation, but in some cases improve speed.  If TRYTOCOMPACT is not specified, history compacting is not attempted and the accuracy is high.  The flags NOCONTROL, TRUNCDONTCUT and NOSTEPLIMIT also increase speed at the expense of accuracy in some cases.

Supported Analyses

Distortion, Noise, and Pole-Zero Analysis not supported


Q   Bipolar Junction Transistors (BJTs)

General form:

QXXXXXXX NC NB NE <NS> MNAME <AREA> <OFF> <IC=VBE,VCE> <TEMP=T>

Example:

Q23 10 24 13 QMOD IC=0.6,5.0

q2 5 4 0 qnd

NC, NB and NE are the collector, base and emitter nodes, respectively. NS is the substrate node. If this is not given, ground is assumed. MNAME is the model name, AREA is the area factor, and OFF indicates a optional initial value for the element in a dc analysis. If the area factor is omitted, 1.0 is assumed. The optional initial value IC=VBE,VCE is meant to be used together with UIC in a transient analysis. See the description of the .IC statement for a better way to set transient initial conditions. The optional TEMP value is the temperature at which this device operates. It overrides the temperature specified as a option.

BJT Model

.MODEL {model name} NPN <model parameters>

.MODEL {model name} PNP <model parameters>

The bipolar transistor model in AIM-Spice is an adaptation of the Gummel-Poon model. In AIM-Spice the model is extended to include high bias effects. The model automatically simplifies to Ebers-Moll if certain parameters are not given (VAF, IKF, VAR, IKR).

Name	Parameter	Units	Default
IS	Transport saturation current	A	1e-16
BF	Ideal maximum forward beta	-	100
NF	Forward current emission coefficient	-	1.0
VAF	Forward Early voltage	V	infinite
IKF	Corner for forward beta high current roll-off	A	infinite
ISE	B-E leakage saturation current	A	0
NE	B-E leakage emission coefficient	-	1.2
BR	Ideal maximum reverse beta	-	1
NR	Reverse current emission coefficient	-	1
VAR	Reverse Early voltage	V	infinite
IKR	Corner for reverse beta high current roll-off	A	infinite
ISC	B-C leakage saturation current	A	0
NC	B-C leakage emission coefficient	-	2
RB	Zero bias base resistance	Ω	0
IRB	Current where base resistance falls halfway to its minimum value	A	infinite
RBM	Minimum base resistance at high currents	Ω	RB
RE	Emitter resistance	Ω	0
RC	Collector resistance	Ω	0
CJE	B-E zero bias depletion capacitance	F	0
VJE	B-E built-in potential	V	0.75
MJE	B-E junction exponential factor	-	0.33
TF	Ideal forward transit time	s	0
XTF	Coefficient for bias dependence of TF	-	0
VTF	Voltage describing VBC dependence of TF	V	infinite
ITF	High current parameter for effect on TF	A	0
PTF	Excess phase at f=1.0/(TF · 2π) Hz	Deg
CJC	B-C zero bias depletion capacitance	F	0
VJC	B-C built-in potential	V	0.75
MJC	B-C junction exponential factor	-	0.33
XCJC	Fraction of B-C depletion capacitance connected to internal base node.	-	1
TR	Ideal reverse transit-time	s	0
CJS	zero-bias collector-substrate capacitance	F	0
VJS	Substrate junction built-in potential	V	0.75
MJS	Substrate junction exponential factor	-	0
XTB	Forward and reverse beta temperature exponent	-	0
EG	Energy gap for temperature effect on IS	eV	1.11 (Si)
XTI	Temperature exponent for effect on IS	-	3
KF	Flicker-noise coefficient	-	0
AF	Flicker-noise exponent	-	1
FC	Coefficient for forward-bias depletion capacitance formula	-	0.5
TNOM	Parameter measurement temperature	°C	27
Temperature Effects

The temperature appears explicitly in the exponential terms.

Temperature dependence of the saturation current in the model is determined by:

where k is Boltzmann's constant, q is the electronic charge, EG is the energy gap, and XTI is the saturation current temperature exponent. EG and XTI are model parameters.

The temperature dependence of the forward and reverse beta is given by:

where XTB is a user supplied model parameter. Temperature effects on beta are implemented by appropriate adjustment of the model parameters BF, ISE, BR, and ISC.

Supported Analyses

All


R   Resistors

General form:

RXXXXXXX N1 N2 VALUE

Examples:

R1 1 2 100

RB 1 2 10K

RBIAS 4 8 10K

N1 and N2 are the two element nodes. VALUE is the resistance in Ohm. The value can be positive or negative, but not zero.

Semiconductor Resistors

General form:

RXXXXXXX N1 N2 <VALUE> <MNAME> <L=LENGTH> <W=WIDTH> <TEMP=T>

Example:

rload 2 10 10K

RMOD 3 7 RMODEL L=10U W=1U

This is a more general model for the resistor than the one presented above. It gives you the possibility to model temperature effects and to calculate the resistance based on geometry and processing information . VALUE, if given, defines the resistance, and information on geometry and processing will be ignored. If MNAME is specified, the resistance value is calculated based on information about the process and geometry in the model statement. If VALUE is not given, MNAME and LENGTH must be specified. If WIDTH is not given, it will be given the default value. The optional TEMP value is the temperature at which this device operates.  It overrides the temperature specified in the option value.

Resistor Model

.MODEL {model name} R <model parameters>

The resistor model contains process related parameters and the resistance value is a function of the temperature. The parameters are:

Name	Parameter	Unit	Default
TC1	First order temperature coefficient	1/°C	0.0
TC2	Second order temperature coefficient		0.0
RSH	Sheet resistance	Ω/	-
DEFW	Default width	m	1e-6
NARROW	Narrowing due to side etching	m	0.0
TNOM	Parameter measurement temperature	°C	27
The following expression is used for calculating the resistance value:

DEFW defines a default value of W. If either RSH or L is given, a default value of 1 kOhm is used for R.

Temperature Effects

The temperature dependence of the resistance is given by a polynomial:

where T is the operating temperature, TNOM is the nominal temperature, and TC1 and TC2 are the first- and second order temperature coefficients respectively.

Supported Analyses

All


S   Voltage Controlled Switch

General form:

SXXXXXXX N+ N- NC+ NC- MODEL <ON> <OFF>

Examples:

s1 1 2 3 4 switch1 ON

s2 5 6 3 0 sm2 off

N+ and N- are the positive and negative connecting nodes of the switch, respectively. NC+ and NC- are the positive and negative controlling nodes, respectively.

Switch Model

.MODEL {model name} SW <model parameters>

The switch model allows modeling of an almost ideal switch in AIM-Spice. The switch is not quite ideal in the resistance cannot change from 0 to infinity, but must have a finite positive value. The on and off resistances should therefore be chosen very small and very large, respectively, compared to other circuit elements. The model parameters are as follows:

Name	Parameter	Units	Default
VT	Threshold voltage	V	0
VH	Hysteresis voltage	V	0
RON	On resistance	Ω	1
ROFF	Off resistance	Ω	1/GMIN
An ideal switch is highly non-linear. The use of switches can cause large discontinuities in node voltages. A rapid change such as that associated with a switching operation can cause problems with roundoff and tolerance which may lead to erroneous results or problems in selecting proper time steps. To reduce such problems, follow these steps:

Do not set the switch impedances higher and lower than necessary.

Reduce the tolerance during a transient analysis. This is done by specifying a value for TRTOL less than the default value of 7.0. Use for example 1.0.

When switches are placed near capacitors, you should reduce the size of CHGTOL to, for example, 1e-16.

Supported Analyses

Distortion Analysis not supported


T   Transmission Lines (Lossless)

General form:

TXXXXXXX N1 N2 N3 N4 Z0=VALUE <TD=VALUE>

+ <F=FREQ <NL=NRMLEN>> <IC=V1,I1,V2,I2>

Example:

T1 1 0 2 0 Z0=50 TD=10NS

N1 and N2 are the nodes for port 1, N3 and N4 are the nodes for port 2. Z0 is the characteristic impedance of the line. The length of the line can be specified in two different ways. The transmission delay TD can be specified directly. Alternatively, a frequency F may be given together with the normalized length of the line, NL (normalized with respect to the wavelength at the frequency F). If a frequency is specified and NL is omitted, 0.25 is assumed. Note that even though both ways of specifying line length is enclosed in brackets, one must be specified.

Note that this element models only one propagation mode. If all four modes are distinct in the actual circuit, then two modes may be excited. To simulate such a situation, two transmission-line elements are required.

The optional initial values consists of voltages and currents at each of the two ports. Note that these values are used only if the option UIC are specified in a transient analysis.

Supported Analyses

Distortion, Noise, and Pole-Zero Analysis not supported


U   Uniform Distributed RC Lines (URC)

General form:

UXXXXXXX N1 N2 N3 MNAME L=LENGTH <N=LUMPS>

Example:

U1 1 2 0 URCMOD L=50U

URC2 1 12 2 UMODL L=1MIL N=6

N1 and N2 are the two nodes of the RC line itself, while N3 is the node of the capacitances. MNAME is the name of the model, LENGTH is the length of the line in meters. LUMPS, if given, is the number of segments to use in modeling the RC line.

URC Model

.MODEL {model name} URC <model parameters>

The model is accomplished by a subcircuit expansion of the URC line into a network of lumped RC segments with internally generated nodes. The RC segments are in a geometric progression, increasing toward the middle of the URC line, with K as a proportionality constant. The number of lumped segments used, if not specified on the URC line, is determined by the following expression:

The URC line is made up strictly of resistor and capacitor segments unless the ISPERL parameter is given a non-zero value, in which case the capacitors are replaced with reverse biased diodes with a zero-bias junction capacitance equivalent to the capacitance replaced, and with a saturation current of ISPERL amps per meter of transmission line and an optional series resistance equivalent to RSPERL ohms per meter.

Name	Parameter	Units	Default
K	Propagation constant	-	2.0
FMAX	Maximum frequency	Hz	1.0G
RPERL	Resistance per unit length	Ω/m	1000
CPERL	Capacitance per unit length	F/m	1e-15
ISPERL	Saturation current per unit length	A/m	0
RSPERL	Diode resistance per unit length	Ω /m	0
Supported Analyses

All


V   Independent Voltage Sources

General form:

VXXXXXXX N+ N- <<DC> DC/TRAN VALUE> <AC <ACMAG <ACPHASE>>>

+ <DISTOF1 <F1MAG <F1PHASE>>> <DISTOF2 <F2MAG <F2PHASE>>>

Examples:

vin 21 0 pulse(0 5 1ns 1ns 1ns 5us 10us)

vcc 10 0 dc 6

vmeas 12 9

N+ and N- are the positive and negative nodes, respectively. Note that the voltage source need not to be grounded. Positive current flows from the positive node through the source to the negative node. If you insert a voltage source with a zero value, it can be used as an Ampere meter.

DC/TRAN is the source value during a DC or a transient analysis. The value can be omitted if it is zero for both the DC and transient analysis. If the source is time invariant, its value can be prefixed with DC.

ACMAG is amplitude value and ACPHASE is the phase value of the source during an AC analysis. If ACMAG is omitted after the keyword AC, 1 is assumed. If ACPHASE is omitted, 0 is assumed.

DISTOF1 and DISTOF2 are the keywords that specify that the independent source has distortion inputs at the frequencies F1 and F2 respectively (see the description of the distortion analysis parameters). The keywords may be followed by an optional magnitude and phase. The default values of the magnitude and phase are 1.0 and 0.0 respectively.

All independent sources can be assigned time varying values during a transient analysis. If a source is assigned a time varying value, the value at t=0 is used during a DC analysis. There are 5 predefined functions for time varying sources: pulse, exponent, sinusoidal, piece-wise linear, and single frequency FM. If parameters are omitted, the default values shown in the tables below will be assumed. DT and T2 are the increment time and final time in a transient analysis, respectively (see Transient Analysis).

Pulse

General form:

PULSE(V1 V2 TD TR TF PW PER)

Parameters	Default values	Units
V1 (initial value)	None	Volt
V2 (pulsed value)	None	Volt
TD (delay time)	0.0	seconds
TR (rise time)	DT	seconds
TF (fall time)	DT	seconds
PW (pulse width)	T2	seconds
PER (period)	T2	seconds
Example:

VIN 3 0 PULSE(1 5 1S 0.1S 0.4S 0.5S 2S)

Sinus

General form:

SIN(V0 VA FREQ TD THETA)

Parameters	Default values	Units
V0 (offset)	None	Volt
VA (amplitude)	None	Volt
FREQ (frequency)	1/T2	Hz
TD (delay)	0.0	seconds
THETA(damping factor)	0.0	1/seconds
The shape of the waveform is:

0 < time < TD

V = V0

TD < time < T2

Example:

VIN 3 0 SIN(2 2 5 1S 1)

Exponent

General form:

EXP(V1 V2 TD1 TAU1 TD2 TAU2)

Parameters	Default values	Units
V1 (initial value)	None	Volt
VA (pulsed value)	None	Volt
TD1(rise delay time)	0.0	seconds
TAU1(rise time constant)	DT	seconds
TD2 (delay fall time)	TD1+DT	seconds
TAU2 (fall time constant)	DT	seconds
The shape of the waveform is:

0 < time < TD1

V = V1

TD1 < time < TD2

TD2 < time < T2

Example:

VIN 3 0 EXP(1 5 1S 0.2S 2S 0.5S)

Piece-wise Linear

General form:

PWL(T1 V1 <T2 V2 T3 V3 T4 V4 T5 V5 ....>)

Parameters and default values:

Every pair of values (Ti, Vi) specifies that the value of the source is Vi at Ti. The value of the source between these values is calculated using a linear interpolation.

Example:

VCLOCK 7 5 PWL(0 0 1 0 1.2 4 1.6 2.0 2.0 5.0 3.0 1.0)

Single frequency FM

General form:

SFFM(V0 VA FC MDI FS)

Parameters	Default values	Units
V0 (offset)	None	Volt
VA (amplitude)	None	Volt
FC (carrier frequency)	1/T2	Hz
MDI (modulation index)	None	-
FS (signal frequency)	1/T2	Hz
The shape of the waveform is:

Example:

VIN 12 0 SFFM(2 1 2 5 0.2)

Supported Analyses

All


W   Current Controlled Switch

General form:

WYYYYYYY N+ N- VNAME MODEL <ON> <OFF>

Examples:

w1 1 2 vclock switchmod1

w2 3 0 vramp sm1 ON

wreset 5 6 vclk lossyswitch OFF

N+ and N- are the positive and negative nodes of the switch, respectively. The control current is defined as the current flowing through the specified voltage source. The direction of positive control current is from the positive node through the source to the negative node.

Switch Model

.MODEL {model name} CSW <model parameters>

The switch model allows modeling of an almost ideal switch in AIM-Spice. The switch is not quite ideal in the resistance cannot change from 0 to infinity, but must have a finite positive value. The on and off resistances should therefore be chosen very small and very large, respectively, compared to other circuit elements. The model parameters are as follows:

Name	Parameter	Units	Default
IT	Threshold current	A	0
IH	Hysteresis current	A	0
RON	On resistance	Ω	1
ROFF	Off resistance	Ω	1/GMIN
An ideal switch is highly non-linear. The use of switches can cause large discontinuities in node voltages. A rapid change such as that associated with a switching operation can cause problems with roundoff and tolerance which may lead to erroneous results or problems in selecting proper time steps. To reduce such problems, follow these steps:

Do not set the switch impedances higher and lower than necessary.

Reduce the tolerance during a transient analysis. This is done by specifying a value for TRTOL less than the default value of 7.0. Use for example 1.0.

When switches are placed near capacitors, you should reduce the size of CHGTOL to, for example, 1e-16.

Supported Analyses

Distortion Analysis not supported.


Z   GaAs Metal Semiconductor Field Effect Transistors (MESFETs)

General form (Level 1):

ZXXXXXXX ND NG NS MNAME <A=VALUE> <OFF> <IC=VDS,VGS>

General form (Level 2 and 3):

ZXXXXXXX ND NG NS MNAME <L=VALUE> <W=VALUE> <OFF>

+ <IC=VDS,VGS> <TD=T> <TS=T>

Example:

z1 7 2 3 zm1 off

z1 0 2 0 mesmod l=1u w=20u

ND, NG and NS are the drain, gate and source nodes, respectively. MNAME is the model name, A is the area factor, L is the channel length, W is the channel width, and OFF indicates a optional initial value for the element in a DC analysis. If the area factor is omitted, 1.0 is assumed. The optional initial value IC=VDS,VGS is meant to be used together with UIC in a transient analysis. See the description of the .IC statement for a better way to set transient initial conditions. The optional TD and TS values for Levels 2 and 3 are the operation drain and source temperatures, respectively, in centigrade. They override the temperature specified in the option value. If length and/or width are not specified, AIM-Spice will use default values,  L=1μm  and  W=20μm  for Levels 2 and 3.

MESFET Model

.MODEL {model name} NMF <model parameters>

.MODEL {model name} PMF <model parameters>

In AIM-Spice, three MESFET models are implemented. The difference between the models is in the formulation of the IV-characteristics. The parameter LEVEL selects which model to use.

LEVEL=1	Model proposed by Statz et al. [9]

LEVEL=2	Unified extrinsic model for uniformly doped channel (as described in Section 4.4.3 in [2])

LEVEL=3	Unified extrinsic model for delta doped channel (as described in Section 4.4.4 in [2])

MESFET model parameters common for all levels:

Name	Parameter	Units	Default
VTO	Zero-bias threshold voltage	V	-2.0   (level 1) -1.26 (level 2, 3)
RD	Drain ohmic resistance	Ω	0
RS	Source ohmic resistance	Ω	0

Model parameters specific for Level 1:

Name	Parameter	Units	Default
IS	Junction saturation current	A	1e-14
BETA	Transconductance parameter	A/V2	2.5e-3
B	Doping tail extending parameter	1/V	0.3
ALPHA	Saturation voltage parameter	1/V	2
LAMBDA	Channel length modulation parameter	1/V	0
CGS	Zero-bias G-S junction capacitance	F	0
CGD	Zero-bias G-D junction capacitance	F	0
PB	Gate junction potential	V	1
KF	Flicker noise coefficient	-	0
AF	Flicker noise exponent	-	1
FC	Coefficient for forward-bias depletion capacitance formula	-	0.5
The model parameters for MESFET Levels 2 and 3 are listed below. Note that the default values correspond to the n-channel MESFET used as an example in Section 4.4 in [2].

Name	Parameter	Units	Default
D	Depth of device (level 2 only)	m	0.12μm
DU	Depth of uniformly doped layer (level 3 only)	m	0.035μm
RG	Gate ohmic resistance	Ω	0
RDI	Internal drain ohmic resistance	Ω	0
RSI	Internal source ohmic resistance	Ω	0
RI	Resistance in series with Cgs (level 2 only)	Ω	0
RF	Resistance in series with Cgd (level 2 only)	Ω	0
PHIB	Effective Schottky barrier height	eV	0.5
ASTAR	Effective Richardson constant		4.0E4
GGR	Junction conductance at reverse bias		40
DEL	Reverse junction conductance inverse ideality factor	-	0.04
N	Junction ideality factor	-	1
LAMBDA	Output conductance parameter	1/V	0.045
LAMBDAHF	Output conductance parameter at high frequencies	1/V	0.045
VS	Saturation velocity (level 2 only)	m/s	1.5E5
BETA	Transconductance parameter (level 3 only)		0.0085
ETA	Subthreshold ideality factor	-	1.73
M	Knee shape parameter	-	2.5
ALPHA	Bulk charge parameter	1/V	0
MC	Knee shape parameter	-	3.0
SIGMA0	DIBL parameter	-	0.081
VSIGMAT	DIBL parameter	V	1.01
VSIGMA	DIBL parameter	V	0.1
MU	Low field mobility		0.23
THETA	Mobility enhancement coefficient		0
MU1	First temperature parameter for mobility		0
MU2	Second temperature parameter for mobility		0
ND	Substrate doping (level 2 only)		3.0E23
NDU	Uniform layer doping (level 3 only)		1.0E22
DELTA	Transition width parameter	-	5.0
TC	Transconductance compression factor	1/V	0
ZETA	Transconductance compensation factor	-	1.0
NDELTA	Doping of delta doped layer (level 3 only)		6.0E24
TH	Thickness of delta doped layer (level 3 only)	m	0.01μm
TVTO	Temperature coefficient for VTO	V/K	0
TLAMBDA	Temperature coefficient for LAMBDA	°C	∞
TETA0	First temperature coefficient for ETA	°C	∞
TETA1	Second temperature coefficient for ETA	°C	0 K
TMU	Temperature coefficient for mobility	°C	27
XTM0	First exponent for temperature dependence of mobility	-	0
XTM1	Second exponent for temperature dependence of mobility	-	0
XTM2	Third exponent for temperature dependence of mobility	-	0
TPHIB	Temperature coefficient for PHIB	eV/K	0
TGGR	Temperature coefficient for GGR	1/K	0
KS	Sidegating coefficient	-	0
VSG	Sidegating voltage	V	0
TF	Characteristic temperature determined by traps	°C	TEMP
FLO	Characteristic frequency for frequency dependent output conductance	Hz	0
DELFO	Frequency range used for frequency dependent output conductance calculation	Hz	0
AG	Drain-source correction current gain	-	0
RTC1	First order temperature coefficient for parasitic resistances	1/°C	0
RTC2	Second order temperature coefficient for parasitic resistances	1/°C2	0
For Levels 2 and 3 you can choose between intrinsic or extrinsic model by proper use of parameters RD, RS, and RDI, RSI.  If you specify values for RD and RS, you select the intrinsic model with parasitic resistances applied externally.  The extrinsic model is selected by specifying values for RDI and RSI.

Temperature effects (level 2 and 3 only)

The temperature appears explicitly in the several exponential terms. In addition, the temperature dependence of several key parameters are modeled as shown below (in terms of absolute temperatures).

The dependence of the threshold voltage on temperature is modeled by the equation

where TNOM is the nominal temperature specified as an option.

The mobility is adjusted according to

where μimp is the impurity scattering limited mobility, μpo is the polar optical scattering limited mobility and μn0 is the effective zero bias mobility used in calculating the drain current.

The output conductance parameter is adjusted according to

.

The subthreshold ideality factor is adjusted according to

The following equation is used to adjust all the parasitic resistances:

,

Drain current equations

For level 2:

For level 3:

Gate current equations

Supported Analyses

Level 1:	All

Level 2, 3:	Distortion, Noise, and Pole-Zero Analysis not supported


.INCLUDE statement

General form:

.INCLUDE {filename}

Example:

.include d:\aimspice\cmos.mod

filename is the name of the file with path extension if needed, that will be included in the circuit netlist.


.SUBCKT statement

General form:

.SUBCKT SUBNAME N1 N2 N3 ...

Example:

.SUBCKT OPAMP 1 2 3 4 5

A subcircuit definition starts with the .SUBCKT statement. SUBNAME is the name of the subcircuit used when referencing the subcircuit.  N1, N2, ... are external nodes, excluding "0". The group of elements that follows directly after the .SUBCKT statement defines the topology of the subcircuit. The definition must end with the .ENDS statement. Control statements are not allowed in a subcircuit definition. A subcircuit definition can contain other subcircuit definitions, device models, and call to other subcircuits. Note that device models and subcircuit definitions within a subcircuit definition are local to that subcircuit and are not available outside. Nodes used in a subcircuit are also local, except "0" (ground) which is always global.


.ENDS statement

General form:

.ENDS <SUBNAME>

Example:

.ENDS OPAMP

Each subcircuit definition must end with the .ENDS statement. A subcircuit name after .ENDS indicates ending of the corresponding subcircuit. Otherwise all definitions are ended.


Call to subcircuits

General form:

XYYYYYYY N1 <N2 N3 ...> SUBNAME

Example:

X1 2 4 17 3 1 MULTI


.NODESET statement

General form:

.NODESET V(NODENAME)=VALUE V(NODENAME)=VALUE ...

Example:

.NODESET V(12)=4.5 V(4)=2.23

This control statement helps AIM-Spice locating the dc operating point. Specified node voltages are used as a first guess of the dc operating point. This statement is useful when analyzing bistable circuits. Normally, .NODESET is not needed.


.IC statement

General form:

.IC V(NODENAME)=VALUE V(NODENAME)=VALUE ...

Example:

.IC V(11)=5 V(1)=2.3

This control statement is used for specifying initial values of a transient analysis. This statement is interpreted in two ways, depending on whether UIC is specified or not.

If UIC is specified, the node voltages in the .IC statement will be used to compute initial values for capacitors, diodes, and transistors. This is equivalent to specify IC=... for each element, only more convenient. IC=... can still be specified and will override the .IC values. AIM-Spice will not perform any operating point analysis when this statement is used, and therefore, the statement should be used with care.

AIM-Spice will perform an operating point analysis before a transient analysis if UIC is not specified. Then the .IC statement has no effect.


Bugs Reported by Berkeley

Models defined within subcircuits are not handled correctly. Models should be defined outside the subcircuit definition starting with the .SUBCKT statement and ending with .ENDS.

Convergence problems can sometimes be avoided by relaxing the maximum stepsize parameter for a transient analysis.

The base node of the bipolar transistor (BJT) is incorrectly modeled and should not be used.  Use instead a semiconductor capacitor to model base effects.

Charge storage in MOS devices based on the Meyer model is incorrectly calculated.

Transient simulations of strictly resistive circuits (typical for first runs or tests) allow a time step that is too large (e.g., a sinusoidal source driving a resistor).  There is no integration error to restrict the time step.  Use the maximum stepsize parameter or include reactive elements.


References

[1]	B. Johnson, T. Quarles, A. R. Newton, D. O. Pederson and A. Sangiovanni-Vincentelli, SPICE3 Version 3e1 User's Manual, Berkeley.

[2]	K. Lee, M. Shur, T. A. Fjeldly and T. Ytterdal, Semiconductor Device Modeling for VLSI, 1993, Prentice Hall, New Jersey.

[3]	B. J. Sheu, D. L. Scharfetter, P. K. Ko, and M. C. Jeng, BSIM: Berkeley Short-Channel IGFET Model for MOS Transistors, IEEE J. Solid-State Circuits, vol. 22, no. 4, pp. 558-566, 1987.

[4]	T. Sakurai and A. R. Newton, A simple MOSFET Model for Circuit Analysis and its applications to CMOS gate delay analysis and series-connected MOSFET Structure, ERL Memo No. ERL M90/19, Electronics Research Laboratory, University of California, Berkeley, March 1990.

[5]	J. H. Huang, Z. H. Liu, M. C. Jeng, P. K. Ko, and C. Hu, A Robust Physical and Predictive Model for Deep-Submicrometer MOS Circuit Simulation, in Proc. IEEE 1993 Custom Integrated Circuits Conference, p. 14.2.1, 1993.

[6]	C. Turchetti, P. Prioretti, G. Masetti, E. Profumo, and M. Vanzi, A Meyer-like Approach for the Transient Analysis of Digital MOS ICs, IEEE Trans. on Computer-Aided Design, vol. 5, no. 10, pp. 499-507, Oct. 1986.

[7]	D. E. Ward and R. W. Dutton, A Charge-Oriented Model for MOS Transistor Capacitances, IEEE J. of Solid-State Circuits, vol. 13, no. 5, pp. 703-708,  Oct. 1978.

[8]	J. S. Roychowdhury and D. O. Pederson, Efficient Transient Simulation of Lossy Interconnect, in Proceedings of the 28th ACM/IEEE Design Automation Conference, June 17-21 1991, San Francisco.

[9]	H. Statz, P. Newman, I. W. Smith, R. A. Pucel, and H. A. Haus, GaAs FET Device and Circuit Simulation in SPICE, IEEE Trans. on Electron Devices, vol. 34, no. 2, pp. 160-169,  Feb. 1987.