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setting up stimuli

whlinfei

 Hi all,

I am using cadence virtuoso schematic and spectra as simulator. 

 I need a PWM signal for my simulation. The way I want to ( I know ) set up is that using a VCVS source as the output and a triangular wave and the input signal as the inputs. After comparing these two and setting the gain of this dependent source high enough( say 10000) and output maximum and minimun to a desired value, I can get PWM without delay nor distortion. 

 The problem I have right now is I don't know how I can generate a triangular waveform. There is no triangular wave stimuli in spectra.

Can anyone help me with that or is there some other way to generate PWM?

Thanks !

 

Best Regards,

whlinfei 

  • Andrew Beckett

    You don't need a specific triangle source, because this is a form of "pulse" source:

      tri (tri 0) vsource type=pulse val1=1 val0=0 rise=10n fall=10n width=0 period=20n

    Use vsource from analogLib (or vpulse), and set the rise and fall times to be half the period, and the width to be 0. That will do what you want.

    Regards,

    Andrew.

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