false phase in AC analysis

[gevy]

I simulate AC analysis of Op Amp by using of Spectre (Cadence).
Sometimes false 180° is added or subtracted to phase characteristic.
How I can to remove this error ?

 

[starcoming]

Do you mean when the phase is increased or decreased to some extent, there is be a 180 substracted or added? This is normal for the display.
If it is not this case ,then it may be a bug for the tool.

 

[GDF]

I simulate AC analysis of Op Amp by using of Spectre (Cadence).
Sometimes false 180° is added or subtracted to phase characteristic.
How I can to remove this error ?

Are you sure that you probe the right node, for example, probe the positive input
and positive output?or positive input and negative output?

 

[gevy]

I measure phase between noninverting input and output of Op Amp.
Sometimes false 180° is added or subtracted to phase characteristic near zero frequency ! It is error of simulation. I am sure that zero frequency phase is zero.