how to get cut-off frequency waveform from Cadence

[ethan]

cadence recommended cutoff

for a single NMOS transistor?

I knew let |A(jw)|= id/Iin=1, but I found I couldn't get it from AC analsis waveform. Maybe I have done wrong. Is there anybody have done this before? Thanks.

 

[naughtyboy]

I remember that I did that using AC simulation. Plot the gate current Ig and channel current Ids to evaluate the omega_T.

 

[v_naren]

hello there
1) Setup a proper biasing circuit first.
2) Then hook up two ports...."psin" from analog lib and then run a s-paramter analysis over the frequency range for which the model of the MOSFET is valid...

3) now after simu plot y21 in magnitude or in dB then find the frequency at which the mag/dB are 1/0dB respectively and u get fT...


please note that u need to set the biasing inductors and DC coupling capacitors to damn high values like 10H and 10F or something!!!

I cannot explain in any more detail.....I have done it using this circuit technique and it has worked always

best of luck

 

[Puppet1]

for a cleaner looking waveform use the cadence cross function and you can actually plot the FT vs. IC curve