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Problem in Cadence Virtuoso AC analysis

OneNewBoy

Hi all,

I am facing an often discussed problem  while simulating a differential pair in cadence virtuoso.

Though I have biased the transistors through DC  (though they are in subthreshold mode), yet when I try do do ac analysis (I follow all regular steps) I get a zero magnitude at output. Ths schematic is attached.

Can someone help me in debugging this ?

 

 

Parents

  • You probably didn't set the AC magnitude on your input source. I see you have a sine source there, but that won't help in an AC simulation. There is a separate parameter to set the magnitude of the input signal. It's a bit hard to see in your picture - you might have set it in which case your Vac variable needs to be non-zero.

    Other than that, your circuit is probably connected up incorrectly.

    Maybe you can post the input.scs from your simulation (the netlist) and then it's easier to take a look?

    Regards,

    Andrew.

Reply

  • You probably didn't set the AC magnitude on your input source. I see you have a sine source there, but that won't help in an AC simulation. There is a separate parameter to set the magnitude of the input signal. It's a bit hard to see in your picture - you might have set it in which case your Vac variable needs to be non-zero.

    Other than that, your circuit is probably connected up incorrectly.

    Maybe you can post the input.scs from your simulation (the netlist) and then it's easier to take a look?

    Regards,

    Andrew.

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