How to perform Stability analysis in Cadence

[gunturikishore]

Hi Friends,

I am trying to do the stability analysis on the Cadence tool and though I know well all the other analysis well, this analysis is confusing me a lot as I am trying it first time.

I am trying to simulate the loop gain of a non-inverting amplifier and somehow strangely it gives very absurd results with -150 dB loop gain.

One doubt I got is whether I have to connect to iprobe or vsource for loop gain calculation?? The result is with same absurd negative gain value with both.

I need to connect vsource as voltage source or I need to place it in series with the loop if I am going to use it??

I hope there are many people use it in this group and help me out of this problem.

Added after 48 minutes:

Solution Found:

Seems like some library components problem in the process I am using. It worked for me with a different process.

 

[sanjeeb]

put an iprobe in series at the point where you want the loop to be broken and then do the stb analysis.

 

[dhasmana]

connect 1K inductor in series of the feedback path and 1K cap to gnd from the input side (of the amplifier) as shown in the attached figure , and do AC analysis.Inductor > open for AC short for DC.