JFET Models (both N and P Channel)

Type Names: njf, pjf

There are two JFET models available, selectable with the level parameter given in the list of model parameters. If level=2 is given, the Parker-Skellern JFET model from Macquarie University in Sydney, Australia will be used. Parameters given must apply to that model. Documentation for this model is available from the Whiteley Research web site, or from
http://www.elec.mq.edu.au/cnerf/spice/spice.html.

If no level parameter is given, or is set to something other than 2, the standard SPICE3 JFET model will be used. This JFET model is derived from the FET model of Shichman and Hodges. The dc characteristics are defined by the parameters vto and beta, which determine the variation of drain current with gate voltage, lambda, which determines the output conductance, and is, the saturation current of the two gate junctions. Two ohmic resistances, rd and rs, are included. Charge storage is modeled by nonlinear depletion layer capacitances for both gate junctions which vary as the -1/2 power of junction voltage and are defined by the parameters cgs, cgd, and pb. The fitting parameter b is a new addition, see[7].

The parameters marked with an asterisk in the area column scale with the area parameter given in the device line.

JFET Model Parameters
name	area	parameter	units	default	example
vto		threshold voltage	V	-2.0	-2.0
beta	*	transconductance parameter	A/V2	1.0e-4	1.0e-3
lambda		channel length modulation parameter	1/V	0	1.0e-4
rd	*	drain ohmic resistance	$\Omega$	0	100
rs	*	source ohmic resistance	$\Omega$	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
is	*	gate junction saturation current	A	1.0e-14	1.0e-14
b		doping tail parameter	-	1	1.1
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	25	50