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vcvs Impedance Dips in Frequency

ChrisDG

Hello,

I am trying to create a near ideal voltage buffer using the components of analogLib. I have tried using vcvs and other controlled sources. All these perform the function correctly but always have sharp frequency spikes and dips in the input and output impedances. I can understand if the spikes are insignificant but some of these come to around 90% of the maximum impedance value so when placed in actual circuits it affects the performance at these frequency notches. I have tried using feedback Rs and Cs but they don't seem to help.

Attached below is one example of vcvs under 2port SP analysis where Z11 is shown.

The port settings are:

Port1: Resistance=50ohm; SourceType=Sine; PortNum=1

Port2: Resistance=50ohm; SourceType=DC; PortNum=2

Simulator: Spectre
SP Analysis: 10M 10GHz ; Single-Ended

Wondered if anyone could recommend a solution.

Thanks.

Chris

Parents
  • Andrew Beckett

    Chris,

    That looks like a numerical artefact given the size of the impedances. Can you do two things (to make it easier for a lazy person like me to test):

    1. Tell me exactly which spectre subversion you're using (this should be at the top of the log file, or what "spectre -W" reports)
    2. Post the input.scs from ADE so that I don't have to re-enter the schematic...

    Thanks,

    Andrew.

Reply
  • Andrew Beckett

    Chris,

    That looks like a numerical artefact given the size of the impedances. Can you do two things (to make it easier for a lazy person like me to test):

    1. Tell me exactly which spectre subversion you're using (this should be at the top of the log file, or what "spectre -W" reports)
    2. Post the input.scs from ADE so that I don't have to re-enter the schematic...

    Thanks,

    Andrew.

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