Gate threshold voltage Vgs-th depends on Drain current Id.

104

01:28:51

This is auto VTO measurement circuit.VTO. In EveryCircuit VTO is defined at Id=0. But in real datasheet of FET , the Vgs(th) is defined at Id=value specified.　For example in datasheet of 2SK2232 it is shown as {
Vth = 0.8 ― 2.0 V  ,VDS = 10V, ID = 1mA}.
This simple circuit can measure real VTO in Id=almost 1mA or Id=almost 0.1mA. The specs of this NMOS-FET are default values of EverCircuit. At upper side of this figure  I put the another FET. Try measurement in various cases.
This circuit can be simply  made by a cheap   relay module from EBY. Simulation is Simulation. Real experiments are very important. Try your DIY.

published 10 years ago

hurz

10 years ago

Yes, EC Vto is at Id 0A and specs take there own values (250uA 500uA 1mA 5mA....). Thats the problem for generic measurement - they all completely have different values defined and Vto is anyway very fuzzy given in spec cuz it is fuzzy from MOS to MOS even from same wafer/production/lot.

faceblast

10 years ago

that's where the peak dca is neat, I put ten IRFP250s from the same batch through it and it shows the Vto was anywhere from 3.02V up to 3.8V. datasheet says 3V.

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