name 
parameter 
units 
default 
example 






























DEFW is used to supply a default value for W if one is not specified for the device. If either RSH or L is not specified, then the standard default resistance value of 1k is used. TNOM is used to override the circuitwide value given on the .OPTIONS control line where the parameters of this model have been measured at a different temperature. After the nominal resistance is calculated, it is adjusted for temperature by the formula:
The (optional) initial condition is the initial (timezero) value of capacitor voltage (in Volts). Note that the initial conditions (if any) apply 'only' if the UIC option is specified on the .TRAN control line.
name 
parameter 
units 
default 
example 




















The (optional) initial condition is the initial (timezero) value of inductor current (in Amps) that flows from N+, through the inductor, to N. Note that the initial conditions (if any) apply only if the UIC option is specified on the .TRAN analysis line.
name 
parameter 
units 
default 
switch 






























The use of an ideal element that is highly nonlinear such as a switch can cause large discontinuities to occur in the circuit node voltages. A rapid change such as that associated with a switch changing state can cause numerical roundoff or tolerance problems leading to erroneous results or timestep difficulties. The user of switches can improve the situation by taking the following steps:
First, it is wise to set ideal switch impedances just high or low enough to be negligible with respect to other circuit elements. Using switch impedances that are close to "ideal" in all cases aggravates the problem of discontinuities mentioned above. Of course, when modeling real devices such as MOSFETS, the on resistance should be adjusted to a realistic level depending on the size of the device being modeled.
If a wide range of ON to OFF resistance must be used in the switches (ROFF/RON >1e;+12), then the tolerance on errors allowed during transient analysis should be decreased by using the .OPTIONS control line and specifying TRTOL to be less than the default value of 7.0. When switches are placed around capacitors, then the option CHGTOL should also be reduced. Suggested values for these two options are 1.0 and 1e16 respectively. These changes inform SPICE3 to be more careful around the switch points so that no errors are made due to the rapid change in the circuit.
DC/TRAN is the dc and transient analysis value of the source. If the source value is zero both for dc and transient analyses, this value may be omitted. If the source value is timeinvariant (e.g., a power supply), then the value may optionally be preceded by the letters DC.
ACMAG is the ac magnitude and ACPHASE is the ac phase. The source is set to this value in the ac analysis. If ACMAG is omitted following the keyword AC, a value of unity is assumed. If ACPHASE is omitted, a value of zero is assumed. If the source is not an ac smallsignal input, the keyword AC and the ac values are omitted.
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 .DISTO control line). 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.
Any independent source can be assigned a timedependent value for transient analysis. If a source is assigned a timedependent value, the timezero value is used for dc analysis. There are five independent source functions: pulse, exponential, sinusoidal, piecewise linear, and singlefrequency FM. If parameters other than source values are omitted or set to zero, the default values shown are assumed. (TSTEP is the printing increment and TSTOP is the final time (see the .TRAN control line for explanation)).
parameter  default value  units 
V1 (initial value)  Volts or Amps  
V2 (pulsed value)  Volts or Amps  
TD (delay time)  0.0  seconds 
TR (rise time)  TSTEP  seconds 
TF (fall time)  TSTEP  seconds 
PW (pulse width)  TSTOP  seconds 
PER(period)  TSTOP  seconds 
time  value 
0  V1 
TD  V1 
TD+TR  V2 
TD+TR+PW  V2 
TD+TR+PW V2  V1 
TSTOP  V1 
parameters  default value  units 
VO (offset)  Volts or Amps  
VA (amplitude)  Volts or Amps  
FREQ (frequency)  1/TSTOP  Hz 
TD (delay)  0.0  seconds 
THETA (damping factor)  0.0  1/seconds 
time  value 
0 to TD  VO 
TD to TSTOP 
parameter  default value  units 
V1 (initial value)  Volts or Amps  
V2 (pulsed value)  Volts or Amps  
TD1 (rise delay time)  0.0  seconds 
TAU1 (rise time constant)  TSTEP  seconds 
TD2 (fall delay time)  TD1+TSTEP  seconds 
TAU2 (fall time  TSTEP  seconds 
time  value 
0 to TD1  V1 
TD1 to TD2  
TD2 to TSTOP 
parameter  default value  units 
VO (offset)  Volts or Amps  
VA (amplitude)  Volts or Amps  
FC (carrier frequency)  1/TSTOP  Hz 
MDI (modulation index)  
FS (signal frequency)  1/TSTOP  Hz 
The shape of the waveform is described by the following equation:
i = g v  v = e v  i = f i  v = h i 
where g, e, f, and h are constants representing transconductance, voltage gain, current gain, and transresistance, respectively.
Examples:
N+ and N are the positive and negative nodes, respectively. Current flow is 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).
The smallsignal AC behavior of the nonlinear source is a linear dependent source (or sources) with a proportionality constant equal to the derivative (or derivatives) of the source at the DC operating point.
The expressions given for V and I may be any function
of voltages and currents through voltage sources in the system. The following
functions of real variables are defined:
abs  asinh  cosh  sin 
acos  atan  exp  sinh 
acosh  atanh  ln  sqrt 
asin  cos  log  tan 
The function "u" is the unit step function, with a value of one for arguments greater than one and a value of zero for arguments less than zero. The function "uramp" is the integral of the unit step: for an input x, the value is zero if x is less than zero, or if x is greater than zero the value is x. These two functions are useful in sythesizing piecewise nonlinear functions, though convergence may be adversely affected.
The following standard operators are defined:
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 for a function in a partial derivative enters a region where that function is undefined.
To get time into the expression you can integrate the current from a constant current source with a capacitor and use the resulting voltage (don't forget to set the initial voltage across the capacitor). Nonlinear resistors, capacitors, and inductors may be synthesized with the nonlinear dependent source. Nonlinear resistors are obvious. Nonlinear capacitors and inductors are implemented with their linear counterparts by a change of variables implemented with the nonlinear dependent source. The following subcircuit will implement a nonlinear capacitor:
Note that this element models only one propagating mode. If all four nodes are distinct in the actual circuit, then two modes may be excited. To simulate such a situation, two transmissionline elements are required. (see the example in \\*(AA for further clarification.)
The (optional) initial condition specification consists of the voltage and current at each of the transmission line ports. Note that the initial conditions (if any) apply 'only' if the UIC option is specified on the .TRAN control line.
Note that a lossy transmission line (see below) with zero loss may be more accurate than than the lossless transmission line due to implementation details.
The LTRA model takes a number of parameters, some of which must
be given and some of which are optional.
name  parameter  units/type  default  example 
R  resistance/length  0.0  0.2  
L  inductance/length  henrys/unit  0.0  9.13e9 
G  conductance/length  mhos/unit  0.0  0.0 
C  capacitance/length  farads/unit  0.0  3.65e12 
LEN  lenght of line  no default  1.0  
REL  breakpoint control  arbitrary unit  1  0.5 
ABS  breakpoint control  1  5  
NOSTEPLIMIT  don't limit timestep to less than line delay  flag  not set  set 
NOCONTROL  don't do complex timestep control  flag  not set  set 
LININTERP  use lineair interpolation  flag  not set  set 
MIXEDINTERP  use lineair when quadratic seems bad  not set  set  
COMPACTREL  special reltol for history compaction  flag  RELTOL  1.0e3 
COMPACTABS  special abstol for history compaction  ABSTOL  1.0e9  
TRUNCNR  use NewtonRaphson method for timestep control  flag  not set  set 
TRUNCDONTCUT  don't limit timestep to keep impulseresponse errors low  flag  not set  set 
NOSTEPLIMIT is a flag that will remove the default restriction of limiting timesteps to less than the line delay in the RLC case. NOCONTROL is a flag that prevents the default limiting of the timestep based on convolution error criteria in the RLC and RC cases. This speeds up simulation but may in some cases reduce the accuracy of results. LININTERP is a flag that, when specified, will use linear interpolation instead of the default quadratic interpolation for calculating delayed signals. MIXEDINTERP is a flag that, when specified, uses a metric for judging whether quadratic interpolation is not applicable and if so uses linear interpolation; otherwise it uses the default quadratic interpolation. TRUNCDONTCUT is a flag that removes the default cutting of the timestep to limit errors in the actual calculation of impulseresponse related quantities. COMPACTREL and COMPACTABS are quantities that control the compaction of the past history of values stored for convolution. Larger values of these lower accuracy but usually increase simulation speed. These are to be used with the TRYTOCOMPACT option, described in the .OPTIONS section. TRUNCNR is a flag that turns on the use of NewtonRaphson 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. REL and ABS are quantities that control the setting of breakpoints.
The option most worth experimenting with for increasing the speed of simulation is REL. The default value of 1 is usually safe from the point of view of accuracy but occasionally increases 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 might not be safe from the viewpoint of accuracy. Breakpoints may usually be entirely eliminated if it is expected the circuit will not display sharp discontinuities. Values between 0 and 1 are usually not required but may be used for setting many breakpoints.
COMPACTREL may also be experimented with when the option TRYTOCOMPACT is specified in a .OPTIONS card. 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 on a .OPTIONS card, history compaction is not attempted and accuracy is high. NOCONTROL, TRUNCDONTCUT and NOSTEPLIMIT also tend to increase speed at the expense of accuracy.
The URC line is made up strictly of resistor and capacitor segments
unless the ISPERL parameter is given a nonzero value, in which case the
capacitors are replaced with reverse biased diodes with a zerobias 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  example  area  
1  K  Propagation Constant    2.0  1.2   
2  FMAX  Maximum Frequency of interest  Hz  1.0G  6.5Meg   
3  RPERL  Resistance per unit length  1000  10    
4  CPERL  Capacitance per unit length  F/m  1.0e15  1pF   
5  ISPERL  Saturation Current per unit length  A/m  0     
6  RSPERL  Diode Resistance per unit length  0     
Two different forms of initial conditions may be specified for some devices. The first form is included to improve the dc convergence for circuits that contain more than one stable state. If a device is specified OFF, the dc operating point is determined with the terminal voltages for that device set to zero. After convergence is obtained, the program continues to iterate to obtain the exact value for the terminal voltages. If a circuit has more than one dc stable state, the OFF option can be used to force the solution to correspond to a desired state. If a device is specified OFF when in reality the device is conducting, the program still obtains the correct solution (assuming the solutions converge) but more iterations are required since the program must independently converge to two separate solutions. The .NODESET control line serves a similar purpose as the OFF option. The .NODESET option is easier to apply and is the preferred means to aid convergence.
The second form of initial conditions are specified for use with the transient analysis. These are true 'initial conditions' as opposed to the convergence aids above. See the description of the .IC control line and the .TRAN control line for a detailed explanation of initial conditions.
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) starting condition on the device for dc analysis. If the area factor is omitted, a value of 1.0 is assumed. The (optional) initial condition specification using IC=VD is intended for use with the UIC option on the .TRAN control line, when a transient analysis is desired starting from other than the quiescent operating point. The (optional) TEMP value is the temperature at which this device is to operate, and overrides the temperature specification on the .OPTION control line.
name  parameter  units  default  example  area  
1  IS  saturation current  A  1.0e14  1.0e14  * 
2  RS  ohmic resistance  0  10  *  
3  N  emission coefficient    1  1.0  
4  TT  transittime  sec  0  0.1ns  
5  CJO  zerobias junction capacitance  F  0  2pF  * 
6  VJ  junction potential  V  1  0.6  
7  M  grading coefficient    0.5  0.5  
8  EG  activation energy  eV  1.11  1.11 Si
0.69 Sbd 0.67Ge 

9  XTI  saturationcurrent temp. exp    3.0  3.0jn
2.0Sbd 

10  KF  flicker noise coefficient    0  
11  AF  flicker noise exponent    1  
12  FC  coefficient for forwardbais depletion capacitance formula    0.5  
13  BV  reverse breakdown voltage  V  infinite  40.0  
14  IBV  current at breakdown voltage  A  1.0e3  
15  TNOM  parameter measurement temperature  C  27  50 
NC, NB, and NE are the collector, base, and emitter nodes, respectively. NS is the (optional) substrate node. If unspecified, ground is used. MNAME is the model name, AREA is the area factor, and OFF indicates an (optional) initial condition on the device for the dc analysis. If the area factor is omitted, a value of 1.0 is assumed. The (optional) initial condition specification using IC=VBE, VCE is intended for use with the UIC option on the .TRAN control line, when a transient analysis is desired starting from other than the quiescent operating point. See the .IC control line description for a better way to set transient initial conditions. The (optional) TEMP value is the temperature at which this device is to operate, and overrides the temperature specification on the .OPTION control line.
The dc model is defined by the parameters IS, BF, NF, ISE, IKF, and NE which determine the forward current gain characteristics, IS, BR, NR, ISC, IKR, and NC which determine the reverse current gain characteristics, and VAF and VAR which determine the output conductance for forward and reverse regions. Three ohmic resistances RB, RC, and RE are included, where RB can be high current dependent. Base charge storage is modeled by forward and reverse transit times, TF and TR, the forward transit time TF being bias dependent if desired, and nonlinear depletion layer capacitances which are determined by CJE, VJE, and MJE for the BE junction , CJC, VJC, and MJC for the BC junction and CJS, VJS, and MJS for the CS (CollectorSubstrate) junction. The temperature dependence of the saturation current, IS, is determined by the energygap, EG, and the saturation current temperature exponent, XTI. Additionally base current temperature dependence is modeled by the beta temperature exponent XTB in the new model. The values specified are assumed to have been measured at the temperature TNOM, which can be specified on the .OPTIONS control line or overridden by a specification on the .MODEL line.
The BJT parameters used in the modified GummelPoon model are listed below. The parameter names used in earlier versions of SPICE2 are still accepted.
Modified GummelPoon BJT Parameters
name  parameter  units  default  example  area  
1  IS  transport saturation current  A  1.0e16  1.0e15  * 
2  BF  ideal maximum forward beta    100  100  
3  NF  forward current emission coefficient    1.0  1  
4  VAF  forward Early voltage  V  infinite  200  
5  IKF  corner for forward beta high current rolloff  A  infinite  0.01  * 
6  ISE  BE leakage saturation current  A  0  1.0e13  * 
7  NE  BE leakage emission coefficient    1.5  2  
8  BR  ideal maximum reverse beta    1  0.1  
9  NR  reverse current emission coefficient    1  1  
10  VAR  reverse Early voltage  V  infinite  200  
11  IKR  corner for reverse beta high current rolloff  A  infinite  0.01  * 
12  ISC  leakage saturation current  A  0  8  
13  NC  leakage emission coefficient    2  1.5  
14  RB  zero bias base resistance  0  100  *  
15  IRB  current where base resistance falls halfway to its min value  A  infinte  0.1  * 
16  RBM  minimum base resistance at high currents  RB  10  *  
17  RE  emitter resistance  0  1  *  
18  RC  collector resistance  0  10  *  
19  CJE  BE zerobias depletion capacitance  F  0  2pF  * 
20  VJE  BE builtin potential  V  0.75  0.6  
21  MJE  BE junction exponential factor    0.33  0.33  
22  TF  ideal forward transit time  sec  0  0.1ns  
23  XTF  coefficient for bias dependence of TF    0  
24  VTF  voltage describing VBC dependence of TF 
V  infinite  
25  ITF  highcurrent parameter
for effect on TF 
A  0  *  
26  PTF  excess phase at freq=1.0/(TF*2PI) Hz  deg  0  
27  CJC  BC zerobias depletion capacitance  F  0  2pF  * 
28  VJC  BC builtin potential  V  0.75  0.5  
29  MJC  BC junction exponential factor    0.33  0.5  
30  XCJC  fraction of BC depletion capacitance
connected to internal base node 
  1  
31  TR  ideal reverse transit time  sec  0  10ns  
32  CJS  zerobias collectorsubstrate capacitance  F  0  2pF  * 
33  VJS  substrate junction builtin potential  V  0.75  
34  MJS  substrate junction exponential factor    0  0.5  
35  XTB  forward and reverse beta
temperature exponent 
  0  
36  EG  energy gap for temperature
effect on IS 
eV  1.11  
37  XTI  temperature exponent for effect on IS    3  
38  KF  flickernoise coefficient    0  
39  AF  flickernoise exponent    1  
40  FC  coefficient for forwardbias
depletion capacitance formula 
  0.5  
41  TNOM  Parameter measurement temperature  C  27  50 
Note that in Spice3f and later, a fitting parameter B has been added. For details, see [9].
name  parameter  units  default  example  area  
1  VTO  threshold voltage (V_{T0})  V  2.0  2.0  
2  BETA  transconductance parameter () transconductance parameter  A/V^{2}  1.0e4  1.0e3  * 
3  LAMBDA  channellength modulation
parameter () 
1/V  0  1.0e4  
4  RD  drain ohmic resistance  0  100  *  
5  RS  source ohmic resistance  0  100  *  
6  CGS  zerobias GS junction capacitance (C_{gs})  F  0  5pF  * 
7  CGD  zerobias GD junction capacitance (C_{gs})  F  0  1pF  * 
8  PB  gate junction potential  V  1  0.6  
9  IS  gate junction saturation current (I_{S})  A  1.0e14  1.0e14  * 
10  B  doping tail parameter    1  1.1  
11  KF  flicker noise coefficient    0  
12  AF  flicker noise exponent    1  
13  FC  coefficient for forwardbias    0.5  
14  TNOM  parameter measurement temperature  C  27  50 
There is some overlap among the parameters describing the junctions, e.g. the reverse current can be input either as IS (in A) or as JS (in A/m^{2}). Whereas the first is an absolute value the second is multiplied by AD and AS to give the reverse current of the drain and source junctions respectively. This methodology has been chosen since there is no sense in relating always junction characteristics with AD and AS entered on the device line; the areas can be defaulted. The same idea applies also to the zerobias junction capacitances CBD and CBS (in F) on one hand, and CJ (in F/m^{2}) on the other. The parasitic drain and source series resistance can be expressed as either RD and RS (in ohms) or RSH (in ohms/sq.), the latter being multiplied by the number of squares NRD and NRS input on the device line.
A discontinuity in the MOS level 3 model with respect to the KAPPA parameter has been detected (see [10]). The supplied fix has been implemented in Spice3f2 and later. Since this fix may affect parameter fitting, the option "BADMOS3" may be set to use the old implementation (see the section on simulation variables and the ".OPTIONS" line).
SPICE level 1, 2, 3 and 6 parameters:
name  parameter  units  default  example  
1  LEVEL  model  index    1 
2  VTO  zerobias threshold voltage (V_{T0})  V  0.0  1.0 
3  KP  transconductance parameter  A/V^{2}  2.0e5  3.1e5 
4  GAMMA  bulk threshold parameter ()  V^{1/2}  0.0  0.37 
5  PHI  surface potential ()  V  0.6  0.65 
6  LAMBDA  channellength modulation
(MOS1 and MOS2 only) () 
1/V  0.0  0.02 
7  RD  drain ohmic resistance  0.0  1.0  
8  RS  source ohmic resistance  0.0  1.0  
9  CBD  zerobias BD junction capacitance  F  0.0  20fF 
10  CBS  zerobias BS junction capacitance  F  0.0  20fF 
11  IS  bulk junction saturation current (I_{S})  A  1.0e14  1.0e15 
12  PB  bulk junction potential  V  0.8  0.87 
13  CGSO  gatesource overlap capacitance
per meter channel width 
F/m  0.0  4.0e11 
14  CGDO  gatedrain overlap capacitance
per meter channel width 
F/m  0.0  4.0e11 
15  CGBO  gatebulk overlap capacitance
per meter channel length 
F/m  0.0  2.0e10 
16  RSH  drain and source diffusion
sheet resistance 
/q  0.0  10.0 
17  CJ  zerobias bulk junction bottom cap.
per sqmeter of junction area 
F/m^{2}  0.0  2.0e4 
18  MJ  bulk junction bottom grading coeff.    0.5  0.5 
19  CJSW  zerobias bulk junction sidewall cap.
per meter of junction perimeter 
F/m  0.0  1.0e9 
20  MJSW  bulk junction sidewall grading coeff.    0.50(level1)
0.33(level2,3) 

21  JS  bulk junction saturation current
per sqmeter of junction area 
A/m^{2}  1.0e8  
22  TOX  oxide thickness  meter  1.0e7  1.0e7 
23  NSUB  substrate doping  1/cm^{3}  0.0  4.0e15 
24  NSS  surface state density  1/cm^{2}  0.0  1.0e10 
25  NFS  fast surface state density  1/cm^{2}  0.0  1.0e10 
26  TPG  type of gate material:
+1 opp. to substrate 1 same as substrate 0 Al gate 
  1.0  
27  XJ  metallurgical junction depth  meter  0.0  1 
28  LD  lateral diffusion  meter  0.0  0.8 
29  UO  surface mobility  cm^{2}/Vs  600  700 
30  UCRIT  critical field for mobility
degradation (MOS2 only) 
V/cm  1.0e4  1.0e4 
31  UEXP  critical field exponent in
mobility degradation (MOS2 only) 
  0.0  0.1 
32  UTRA  transverse field coeff. (mobility)
(deleted for MOS2) 
  0.0  0.3 
33  VMAX  maximum drift velocity of carriers  m/s  0.0  5.0e4 
34  NEFF  total channelcharge (fixed and
mobile) coefficient (MOS2 only) 
  1.0  5.0 
35  KF  flicker noise coefficient    0.0  1.0e26 
36  AF  flicker noise exponent    1.0  1.2 
37  FC  coefficient for forwardbias
depletion capacitance formula 
  0.5  
38  DELTA  width effect on threshold voltage
(MOS2 and MOS3) 
  0.0  1.0 
39  THETA  mobility modulation (MOS3 only)  1/V  0.0  0.1 
40  ETA  static feedback (MOS3 only)    0.0  1.0 
41  KAPPA  saturation field factor (MOS3 only)    0.2  0.5 
42  TNOM  parameter measurement temperature  C  27  50 
The level 4 and level 5 (BSIM1 and BSIM2) parameters are all values obtained from process characterization, and can be generated automatically. J. Pierret [4] describes a means of generating a 'process' file, and the program Proc2Mod provided with SPICE3 converts this file into a sequence of BSIM1 ".MODEL" lines suitable for inclusion in a SPICE input file. Parameters marked below with an * in the l/w column also have corresponding parameters with a length and width dependency. For example, VFB is the basic parameter with units of Volts, and LVFB and WVFB also exist and have units of Voltmeter The formula
is used to evaluate the parameter for the actual device specified with
and
Note that unlike the other models in SPICE, the BSIM model is designed for use with a process characterization system that provides all the parameters, thus there are no defaults for the parameters, and leaving one out is considered an error. For an example set of parameters and the format of a process file, see the SPICE2 implementation notes[3].
For more information on BSIM2, see reference [5].
name  parameter  units  l/w 
VFB  flatband voltage  V  * 
PHI  surface inversion potential  V  * 
K1  body effect coefficient  V^{1/2}  * 
K2  drain/source depletion chargesharing coefficient    * 
ETA  zerobias draininduced barrierlowering coefficient    * 
MUZ  zerobias mobility  cm^{2}/Vs  
DL  shortening of channel  m  
DW  narrowing of channel  m  
U0  zerobias transversefield mobility degradation coefficient  V^{1}  * 
U1  zerobias velocity saturation coefficient  m/V  * 
X2MZ  sens. of mobility to substrate bias at v_{ds}=0  cm^{2}/V^{2}s  * 
X2E  sens. of draininduced barrier lowering effect to substrate bias  V^{1}  * 
X3E  sens. of draininduced barrier lowering effect to drain bias at V_{ds}=V_{dd}  V^{1}  * 
X2U0  sens. of transverse field mobility degradation effect to substrate bias  V^{2}  * 
X2U1  sens. of velocity saturation effect to substrate bias  mV^{2}  * 
MUS  mobility at zero substrate bias and at V_{ds}=V_{dd}  cm^{2}/V^{2}s  
X2MS  sens. of mobility to substrate bias at V_{ds}=V_{dd}  cm^{2}/V^{2}s  * 
X3MS  sens. of mobility to drain bias at V_{ds}=V_{dd}  cm^{2}/V^{2}s  * 
X3U1  sens. of velocity saturation effect on drain bias at V_{ds}=V_{dd}  mV^{2}  * 
TOX  gate oxide thickness  m  
TEMP  temperature at which parameters were measured  C  
VDD  measurement bias range  V  
CGDO  gatedrain overlap capacitance per meter channel width  F/m  
CGSO  gatesource overlap capacitance per meter channel width  F/m  
CGBO  gatebulk overlap capacitance per meter channel length  F/m  
XPART  gateoxide capacitancecharge model flag    
N0  zerobias subthreshold slope coefficient    * 
NB  sens. of subthreshold slope to substrate bias    * 
ND  sens. of subthreshold slope to drain bias    * 
RSH  drain and source diffusion sheet resistance  /q  
JS  source drain junction current density  A/m^{2}  
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  F/m^{2}  
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 charge partition in saturation, while XPART=1 selects a 0/100 drain/source charge partition.
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 an (optional) initial condition on the device for dc analysis. If the area factor is omitted, a value of 1.0 is assumed. The (optional) initial condition specification, using IC=VDS, VGS is intended for use with the UIC option on the .TRAN control line, when a transient analysis is desired starting from other than the quiescent operating point. See the .IC control line for a better way to set initial conditions.
Two ohmic resistances, RD and RS, are included. Charge storage is
modeled by total gate charge as a function of gatedrain and gatesource
voltages and is defined by the parameters CGS, CGD, and PB.
name  parameter  units  default  example  area  
1  VTO  pinchoff voltage  V  2.0  2.0  
2  BETA  transconductance parameter  A/V^{2}  1.0e4  1.0e3  * 
3  B  doping tail extending parameter  1/V  0.3  0.3  * 
4  ALPHA  saturation voltage parameter  1/V  2  2  * 
5  LAMBDA  channellength modulation parameter  1/V  0  1.0e4  
6  RD  drain ohmic resistance  0  100  *  
7  RS  source ohmic resistance  0  100  *  
8  CGS  zerobias GS junction capacitance  F  0  5pF  * 
9  CGD  zerobias GD junction capacitance  F  0  1pF  * 
10  PB  gate junction potential  V  1  0.6  
11  KF  flicker noise coefficient    0  
12  AF  flicker noise exponent    1  
13  FC  coefficient for forwardbias
depletion capacitance formula 
  0.5 