Differential mixer simulation problems with 4.4.6

Discussion in 'Cadence' started by Jack Luminous, Oct 6, 2005.

  1. I am trying to simulate transient and conversion gain for a
    differential Gilbert cell with Spectre.

    In my testbench I have used a "psin" ports in RF, LO and IF terminals
    (pos. node connected to an ideal balun and neg. node to gnd).

    I have simulated the conversion gain both with PSS&PAC and PSS&PXF
    analysis.

    PSS&PAC provides about zero difference in the outputs (i.e. output
    signal level at the IF psin port is somewhat -250dB), when the output
    is taken as differential, before the balun, or single-ended after the
    balun.

    When taking the output as single-ended before the balun at the IF
    output, the result is somewhat reasonable.

    With PXF the result at the same point seems a bit too optimistic, the
    difference is more than 10dB.

    What to do and which simulation method to trust?

    -Jack
     
    Jack Luminous, Oct 6, 2005
    #1
  2. I don't see any particularly good reason why PAC should give you different
    answers from PXF, if you've set up the simulation the same way. If you have a
    single ended input - with a PAC magnitude of 1V, and plot the output either
    differentially, or single ended - then you should get the same results as PXF
    where you specify the output as differential, or the same single ended output,
    and plot the PXF results from the same input results.

    If you're getting different answers, I suspect you've not set things up the same
    way for the two different simulations.

    Regards,

    Andrew.
     
    Andrew Beckett, Oct 17, 2005
    #2
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