How can I modify this Ltspice 2SK170 model to lower the IDSS to 5 ma ?

[tessier]

Hi

How can I modify this Ltspice 2SK170 model to lower the IDSS to 5 ma ?

.model J2sk170 NJF(Beta=59.86m Rs=4.151 Rd=4.151 Betatce=-.5 Lambda=1.923m Vto=-.5024 Vtotc=-2.5m Cgd=20p M=.3805 Pb=.4746 Fc=.5 Cgs=25.48p Isr=84.77p Nr=2 Is=8.477p N=1 Xti=3 Alpha=10u Vk=100 Kf=111.3E-18 Af=1)

Thanx

Paul

 

[dchisholm]

Take a look at the "J.JFET Transistor" entry in the LTSpice "Help" files. I think you want to adjust "Vto" and "Beta" until you get a transfer characteristic (plot of Vgs versus Id, at some constant Vds greater than Vto) that is to your liking.

Dale

 

[tessier]

Hi

Here is the new model for the 2SK170-GR, it have a IDSS of 5.04 ma. with a
9 volt dc source.

.model J2sk170gr NJF(Beta=30m Rs=4.151 Rd=4.151 Betatce=-.5 Lambda=1.923m Vto=-.4274 Vtotc=-2.5m Cgd=20p M=.3805 Pb=.4746 Fc=.5 Cgs=25.48p Isr=84.77p Nr=2 Is=8.477p N=1 Xti=3 Alpha=10u Vk=100 Kf=111.3E-18 Af=1)

Thanx

Paul

 

[jcx]

you probably want to fit to a real fet's measurements: Idss, Vth aren't independent for a given part # they vary together