A problem in Hspice regarding pole zero analysis

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naalald

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When I want to perform the pole zero analysis in Hspice, this warning appears:

**warning** pole analysis stopped - iterno .gt. 100

And only two of the poles are shown. The same story occurs for zero analysis.
The circuit is a fully differential opamp. When I remove the CMFB circuit the problem does not occur and everything is correct. I don't know why. Is there anything wrong with program? Any suggestions?
Thanks.
 

Hi,

How CMFB is implemented? This error will happen if u r ckt has unrealistic element values. hope it helps!!

Thanks,
 

Hi,
Thanks for your reply.
No, the CMBF circuit is all real.
 

Hi,

If its possible send u r netlist, I will check. also which version u use?

Thanks,
 

    naalald

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Hi,
I use Hspice 2007.
 

Hi,

hope u got my PM. increase the PZ iteration. U can ignore the vv low freq. P/Z's

Thanks,
 

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