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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.
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  • Dear Ali,

    > Also, I found a to simulation method, but
    > It's a little tricky.


    Although my personal thought is that you might be trying to establish the negative resistance margin or amplitude limiting characteristics of your sustains amplifier (and there might be more efficient methodologies to provide insight into these), I believe your "tricky" methodology can be provided using the spectre actran analysis. In this analysis, a transient analysis is performed and you specify one or more times in the analysis to perform an AC small-signal analysis. The small-signal analyses are performed using the DC operating points of the devices at the time of the transient analysis you specify. If you create an AC analysis expression for the impedance at some frequency, following the transient analysis, a plot of the result of that expression over time by ADE-L will be produced. By choosing a number of times over your oscillation period after steady-state oscillation is achieved will plot the parameter over your oscillator period. The actran analysis parameters are entered in the transient analysis dialog box from ADE-L or from the spectre command line as detailed in solution ID:

    Solution ID: 11219108

    I hope this helps!

    Shawn
Reply
  • Dear Ali,

    > Also, I found a to simulation method, but
    > It's a little tricky.


    Although my personal thought is that you might be trying to establish the negative resistance margin or amplitude limiting characteristics of your sustains amplifier (and there might be more efficient methodologies to provide insight into these), I believe your "tricky" methodology can be provided using the spectre actran analysis. In this analysis, a transient analysis is performed and you specify one or more times in the analysis to perform an AC small-signal analysis. The small-signal analyses are performed using the DC operating points of the devices at the time of the transient analysis you specify. If you create an AC analysis expression for the impedance at some frequency, following the transient analysis, a plot of the result of that expression over time by ADE-L will be produced. By choosing a number of times over your oscillation period after steady-state oscillation is achieved will plot the parameter over your oscillator period. The actran analysis parameters are entered in the transient analysis dialog box from ADE-L or from the spectre command line as detailed in solution ID:

    Solution ID: 11219108

    I hope this helps!

    Shawn
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