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LSSP Simulation for Floated RF Port is Reliable?

Mehdi Nasr

Hi,

Hope you are doing well and stay fine. I am working on designing cross-coupled or differential RF Rectifiers using Cadence. Rectifiers are highly non-linear devices that cannot be charecterized by SP analysis, so we have to use LSSP simulation instead. I have tried finding the magnitude and phase and convert it to Z parameters to be able to match the input, I use the complex conjugate value of the simulated valuein the port to be able to see if the LSSP shows the port is matched or not, but the new results does not show the matching and the results are even worse. Therefore the question arises here that can we rely on the LSSP simulations if the port is floated like what I have in the attached schematic?

How the port calculates the S11?

Parents
  • Tawna

    Hi Mehdi,

    A couple of questions... why are you converting from S-parameters to Z-parameters to match?  I've always designed my matching circuits on the Smith Chart using s-parameters.

    It looks like you have a differential circuit here.   the port is not referenced to ground, which is what I typically see when measuring s-parameters.   Please file a Case via https://support.cadence.com .   You may put me in the cc list when you file the Case.  R&D will need to answer this question.

    best regards,

    Tawna

Reply
  • Tawna

    Hi Mehdi,

    A couple of questions... why are you converting from S-parameters to Z-parameters to match?  I've always designed my matching circuits on the Smith Chart using s-parameters.

    It looks like you have a differential circuit here.   the port is not referenced to ground, which is what I typically see when measuring s-parameters.   Please file a Case via https://support.cadence.com .   You may put me in the cc list when you file the Case.  R&D will need to answer this question.

    best regards,

    Tawna

Children
  • Mehdi Nasr
    in reply to Tawna

    Tawna,

    I do have another question that you may be able to help. Does the LSSP simulation consider the steady-state results? Rectifier input impedance highly depends on the input voltage. So, what is important is having the impedance when the output is in steady-state and completely charged. Does the LSSP consider the results when the output is stable enough? 

    Regards,

  • Andrew Beckett
    in reply to Mehdi Nasr

    LSSP is built around shooting/harmonic balance and so it will find the settled periodic steady state.

    Andrew

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