hi,all
I'm designing an OTA. I have referred some simulation method, I still can't figure out how to sim the OTA to get the curve like this .

I don't mean to be rude, but do you think anyone is likely to be able to understand what you're asking, based on a low resolution jpeg (I can't even read what the expression names are), with no information at all as to what you've referred to or what you think you're trying to simulate?

Please remember that others cannot see inside your head, and so you need to furnish the reader with as much information as possible in order to elucidate your question and increase the chances of somebody being able to answer.

Maybe somebody can guess what you want - I can't.

And by the way, this would have been better in the Circuit Simulation board rather than Analog Design (Ken will probably move it).

Regards,

Andrew.

Hi,
I'm sorry I haven't describe the question clearly,and sorry for post it in a wrong place .
you know ,the OTA is convert  the voltage into current. So I think the V-I relationship is a diagonal .and the slope keeps mainly constant in some range ,eg if Vinput range from -100mv ~ 100mv . So I get the V-I curve as follows .

What you are plotting is I vs. V. I think what you want is gm vs. V (which is an important characteristic of an ota).
gm vs. V is the derivative of I vs. V.
I believe, if you plot the derivative of the curve you show, you should get what you want!

Ahmed

It looks like the transconductance curves for a doublet (the second order form of Gilbert's multi-tanh circuits). Unless there is some switching behavior (CMFB?) there would be no need for PSS analysis. You can get these curves from a simple swept AC analysis, as I describe in my book (Section 3.4.2 starting on page 106 in http://www.designers-guide.org/Books/dg-spice/index.html).

-Ken