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Doing an AC analysis in a time-varying circuit.

Alli

Hi every one :-)

I wanted to do a simulation on an oscillator but I couldn't find any tools in cadence for that. Basically what I want to do is :

Considering an oscillator which is oscillating. During the oscillation I want to do a frequency domain transfer function (AC analysis). I need to linearize the circuit at several point in an oscillation period and find an AC transfer function at a single frequency from an input AC source to the output, and finally plot the magnitude of the transfer function in a period. Basically I want to simulate how the magnitude of a transfer function at a specific frequency is changed during the time (Oscillation period.) 
The frequency which I need the transfer the function is not important it could be exactly at the oscillation frequency or even a little off.
I read about PAC & PXF and if I'm right none of them gives me what I need.
I would appreciate it, if you have any idea.
Parents

  • Dear Ali,

    I am just happy I managed to help you a little!

    Please be aware, however, that if you are trying to estimate how much margin your oscillator has to steady-state oscillation by estimating the average gm in a series of small signal simulations, you are probably not accurately capturing the large signal design margin. From my guess as to what your overall objective might be, I think you might be interested in the start-up gain margin or large signal amplitude limiting.

    In any case, thank you for letting me know!

    Shawn

Reply

  • Dear Ali,

    I am just happy I managed to help you a little!

    Please be aware, however, that if you are trying to estimate how much margin your oscillator has to steady-state oscillation by estimating the average gm in a series of small signal simulations, you are probably not accurately capturing the large signal design margin. From my guess as to what your overall objective might be, I think you might be interested in the start-up gain margin or large signal amplitude limiting.

    In any case, thank you for letting me know!

    Shawn

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