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How to measure AC differential output results using calculator?

xxgenerall
Hi,

I have some problem with AC analysis:
.................................................. .................................................. .........
Run an AC–analysis to simulate the gain of a full-differential amplifier.

How could i measure the output differential signal with the calculator?

I have set this output with calculator:VF("/net28")-VF("/net36"), is it correct for both gain and phase?

Thanks very much.
  • ShawnLogan

    Hi xxgenerall,

     > How could i measure the output differential signal with the calculator? 

    You have not provided your circuit, so I do not know where /net28 and /net36 are in your circuit.

     >  is it correct for both gain and phase? 

    In general, you measure the output as the difference between the positive and negative output nodes. For an AC analysis, the nodal solutions may be complex. Hence, the solution at a particular node will, in general, contain real and imaginary components. Therefore, to determine the magnitude of the differential output gain, use the calculator magnitude function. Similarly, use the calculator phase function to determine the phase of the differential output response.

    Examples for output nodes voutp and voutn:

    mag( getData("voutp" ?result "ac-ac" ?resultsDir <path to results>) - getData("voutn" ?result "ac-ac" ?resultsDir <path to results>))

    phase( getData("voutp" ?result "ac-ac" ?resultsDir <path to results>) - getData("voutn" ?result "ac-ac" ?resultsDir <path to results>)) 

     Shawn 

     

  • xxgenerall

    Thanks for your great help, Shawn.

    I put a VCVS at the differential outputs, transforming differential outputs to a single output. Then, I can use calculator to measure outputs.

    BTW, my circuit is very simple. It is just a full-differential amplifier under AC simulation. I can put a pic next time.

    Thank you. 

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