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OpAmp Simulation in Cadence Spectre

Shahnaf
Hi, I have used OpAmp symbol from Solutions library (default library of cadence). As an initial step, I have simulated a basic circuit in Op Amp. But I am not getting the desired output. Moreover, I have checked the cadence simulation manual for Op Amp. I found something difference in the symbol (from Solutions library) to that of the Cadence manual. Can you please let me know where I am wrong and what needs to be corrected? Thanks, Shahnaz
Parents

  • Looking at your picture (Screenshot-5.png), you have a sine wave input with 5 volts amplitude. With a gain of 10, you'd have 50V output amplitude, but you only have +/-15V supplies, so clearly it wouldn't be able to generate signals that big. That's one mistake, at least (although don't think it's the only one).

    The Solutions library appears to be in the cadence_ms_labs_613 directory - you probably should try to find out where that came from. Is +/- 15V even suitable supply voltages? That's not exactly typical for modern processes...

    Going into the detail of why this circuit (for which I can't see any more than just some screenshots) is not really something I have time to do; maybe somebody else can spare the time - but the right things to  do are probably either to read a book on analog circuit design, or to contact whoever provided this "lab" database and find out how it is intended to be used, or to look at other configurations in the same library and try similar situations. It's an artificial example anyway, so it's not going to help you unless it's realised for a specific process which is the same as the process you're planning to use.

    Regards,

    Andrew.

Reply

  • Looking at your picture (Screenshot-5.png), you have a sine wave input with 5 volts amplitude. With a gain of 10, you'd have 50V output amplitude, but you only have +/-15V supplies, so clearly it wouldn't be able to generate signals that big. That's one mistake, at least (although don't think it's the only one).

    The Solutions library appears to be in the cadence_ms_labs_613 directory - you probably should try to find out where that came from. Is +/- 15V even suitable supply voltages? That's not exactly typical for modern processes...

    Going into the detail of why this circuit (for which I can't see any more than just some screenshots) is not really something I have time to do; maybe somebody else can spare the time - but the right things to  do are probably either to read a book on analog circuit design, or to contact whoever provided this "lab" database and find out how it is intended to be used, or to look at other configurations in the same library and try similar situations. It's an artificial example anyway, so it's not going to help you unless it's realised for a specific process which is the same as the process you're planning to use.

    Regards,

    Andrew.

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