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Help with complete understanding of "vsin" source in Cadence

jdp721
Hi.

I kind of thoroughly Googled before posting this question for seeking help from you guys! 

The "vsin" source (in analogLib) of Cadence has many parameters: 

i) AC magnitude, AC phase, DC voltage
ii) Offset voltage, Amplitude, Frequency,...

Question 1: Internet resources are indicating that parameters in (i) are for AC analysis, while that in (ii) are for Transient analysis - IS THIS TRUE? - because, I have seen in Cadence that changing the "AC phase" led to change in the Transient output waveform - is it so that the "AC phase" field is common between AC and Tran analyses?

Question 2: what is the use of the "DC voltage" in (i) above? - because, I am seeing that people are setting this to '0 V' most of the times without any explanation!
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  • Andrew Beckett

    Just to clarify what Shawn said. If you specify the DC voltage but not the "Offset voltage", when the DC voltage will be used as the mid-voltage of the sinusoid. If Offset voltage is specified, that is used instead (for the transient).

    For a DC analysis (or for any small signal analysis that requires a DC operating point), the DC value of the source is taken as the DC voltage (if specified), or if not specified, it's the time-zero value of the source. These could of course be different...

    Shawn is absolutely right in saying that the AC phase does not affect transient. It's the initial phase for sinusoid that affects that.

    I would generally recommend using vsource rather than vsin (they're the same thing in spectre) because the parameters are better organized.

    Regards

    Andrew.

  • Rohit W
    in reply to Andrew Beckett
    Andrew Beckett said:
    vsource rather than vsin

    found very usefull

Reply
  • Rohit W
    in reply to Andrew Beckett
    Andrew Beckett said:
    vsource rather than vsin

    found very usefull

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