Query about pinch-off point for GaAs FET in ADS

I have a question on how to determine the pinch-off point for a GaAS FET in the simulation in ADS.If the Vds was set to zero bias,what will Vgs be in order to set in order to be less than the pinch-off voltage.THks a million........

Hi,

I think you shouldn't put Vds to 0, try with some other value, half of Vds brake down voltage would be usual. Then make gate voltage as negative as it takes to have drain current fall to 1mA. This would be app value for pinch-off.

flyhigh

try to simulate over a certain Vgs range to find out this point.

So the pinch-off voltage for a GaAS FET remains the same even if the VDS changes? IS the pinch-off voltage at the point when the Ids current rises from zero when it is plotted against VGS?

I plot Id vs. VGs with various Vds. I use the Vgs where Ids takes off as my pinch-off voltage. That all I can think of. Any more idea?