Designing a PCB with DEX > Projects > Circuit Simulation > The Spice Reference Manual > Circuit Description > Circuit Elements and Models > Transistors and Diodes

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 gate-drain and gate-source voltages and is defined by the parameters CGS, CGD, and PB.

name	parameter	units	default	example	area
VTO	pinch-off voltage	V	-2.0	-2.0
BETA	trans-conductance parameter	A/V2	1.0e-4	1.0e-3	*
B	doping tail extending parameter	1/V	0.3	0.3	*
ALPHA	saturation voltage parameter	1/V	2	2	*
LAMBDA	channel-length modulation parameter	1/V	0	1.0e-4
RD	drain ohmic resistance	Ohms	0	100	*
RS	source ohmic resistance	Ohms	0	100	*
CGS	zero-bias G-S junction capacitance	F	0	5pF	*
CGD	zero-bias G-D 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 forward-bias depletion capacitance formula	-	0.5

MESFET Models (NMF/PMF)

MESFET Models (NMF/PMF)