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The MESFET model is derived from the GaAs FET model of Statz et al. as described in [11]. The dc characteristics are defined by the parameters VTO, B, and BETA, which determine the variation of drain current with gate voltage, ALPHA, which determines saturation voltage, and LAMBDA, which determines the output conductance. The formula are given by:
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 
VTO 
pinchoff voltage 
V 
2.0 
2.0 

BETA 
transconductance parameter 
A/V2 
1.0e4 
1.0e3 
* 
B 
doping tail extending parameter 
1/V 
0.3 
0.3 
* 
ALPHA 
saturation voltage parameter 
1/V 
2 
2 
* 
LAMBDA 
channellength modulation parameter 
1/V 
0 
1.0e4 

RD 
drain ohmic resistance 
Ohms 
0 
100 
* 
RS 
source ohmic resistance 
Ohms 
0 
100 
* 
CGS 
zerobias GS junction capacitance 
F 
0 
5pF 
* 
CGD 
zerobias GD junction capacitance 
F 
0 
1pF 
* 
PB 
gate junction potential 
V 
1 
0.6 

KF 
flicker noise coefficient 
 
0 


AF 
flicker noise exponent 
 
1 


FC 
coefficient for forwardbias depletion capacitance formula 
 
0.5 


.