AC analysis problem in Spectre after changing the "AC magnitude"

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devop

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I use spectre to do the AC simulation
when I change the "AC magnitude" of the VSIN in analogLib ,will it bring the change of "AC gain & Phase" result?
there is a big difference in my design ,I don't why
 

AC analysis problem

what kind source of input signal are u used?
usually i use a vdc seting up ac amplitude as 1. if not, u will divide the input signal and calculate it with 20Log
 

Re: AC analysis problem

heartwide said:
what kind source of input signal are u used?
usually i use a vdc seting up ac amplitude as 1. if not, u will divide the input signal and calculate it with 20Log
Click to expand...

VSIN source is used. vac=1.
what's the big difference? I think the phase will not change if you don't change the polarity of it.
 

Re: AC analysis problem

heartwide said:
what kind source of input signal are u used?
usually i use a vdc seting up ac amplitude as 1. if not, u will divide the input signal and calculate it with 20Log
Click to expand...
I use VSIN(DC vol= V bias ,AC magnitude=1) for source of input .whem measure
dB20(VF(out)/VF(in))
then I change AC magnitude=2 ,but the value of dB20(VF(out)/VF(in)) changed ,I don't konw why
 

Re: AC analysis problem


AC magnitude = 1 for direct calculation of gain, if you use mag=2, then gain must be divided by two
 

Re: AC analysis problem

ac gain&phase simulate should include input and output
 

AC analysis problem

Hi

I don't understand what is the problem clearly. please explain clearly.

thanks
 

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