Specifying a Model

To specify a JFET or MESFET model in Star-Hspice, use a JFET element statement and a JFET model statement. The model parameter Level selects either the JFET or MESFET model. LEVEL=1 and LEVEL=2 select the JFET, and LEVEL=3 selects the MESFET. Different submodels for the MESFET LEVEL=3 equations are selected using the parameter SAT.

LEVEL=1	SPICE model
LEVEL=2	Modified SPICE model, gate modulation of LAMBDA
LEVEL=3	Hyperbolic tangent MESFET model (Curtice, Statz, Meta, TriQuint Models)
SAT=0	Curtice model (Default)
SAT=1	Curtice model with user defined VGST exponent
SAT=2	Cubic approximation of Curtice model with gate field degradation (Statz model)
SAT=3	Avant! variable saturation model

The model parameter CAPOP selects the type of capacitor model:

CAPOP=0	SPICE depletion capacitor model
CAPOP=1	Charge conserving, symmetric capacitor model (Statz)
CAPOP=2	Avant! improvements to CAPOP=1

CAPOP=0, 1, 2 can be used for any model level. CAPOP=1 and 2 are most often used for the MESFET LEVEL 3 model.

The model parameter ACM selects the area calculation method:

ACM=0	SPICE method (default)
ACM=1	Physically based method

Example

1. The following example selects the n channel MESFET model, LEVEL=3. It uses the SAT, ALPHA, and CAPOP=1 parameter:

J1 7 2 3 GAASFET
.MODEL GAASFET NJF LEVEL=3 CAPOP=1 SAT=1 VTO=-2.5
+ BETA=2.8E-3 LAMBDA=2.2M RS=70 RD=70 IS=1.7E-14
+ CGS=14P CGD=5P UCRIT=1.5 ALPHA=2

The following example selects an n-channel JFET:

J2 7 1 4 JM1
.MODEL JM1 NJF (VTO=-1.5, BETA=5E-3, CGS=5P, CGD=1P,
+ CAPOP=1 ALPHA=2)

The following example selects a p-channel JFET:

J3 8 3 5 JX

.MODEL JX PJF (VTO=-1.2, BETA=.179M, LAMBDA=2.2M

+ CGS=100P CGD=20P CAPOP=1 ALPHA=2)

Star-Hspice Manual - Release 2001.2 - June 2001