Output resistance Pspice simulation from MbreakN model

Thread Starter

yef smith

Joined Aug 2, 2020
Hello, In PSPICE I need to design analog circuits with the models shown bellow.
What is the resistance it will see from the ports of the mosfet?
How can i test itin PSPICE?
.model Mbreakn NMOS VTO=1 LAMBDA=0.025 KP=0.05m W=2.5u L=0.25u


Joined Oct 28, 2019
P Spice will not tell you the port resistances as you call them.
From your studies of Fets you will know that the resistance G-S is infinite and you find the D-S resistance from the operating point and a datasheet.
BTW as soon as you bias on the FET the current D-S will only be limited by the on resistance of the FET. You need to install a resistor between the battery and D.


Joined May 20, 2015
I'll give an explanation of what I was counting. Judging by the way the question was asked, the questioner doesn't really know what he needs. So I calculated two different impedances. For the first transistor I calculated the dynamic "output impedance" in amplifier mode. For the second transistor I calculated the resistance of the open transistor. Since the values of the mentioned resistances depend on the gate-source voltage, I plotted their dependence on the gate voltage.