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Measure power of opamp circuit

tiennv

HI everyone,

Can you help me?

I want to measure power of inverting summing using opamp.

however, i just use opamp model (written by verilog A) in adhlLib library.

so, i dont know, whether i can measure power consumption. 

Thank.

  • Andrew Beckett

    This is a bit of a strange question. A Verilog-A model won't model the power consumption of the circuit that it is aiming to model unless you've consciously modelled it. Even then, it's got to represent the current consumption of the actual implementation of the circuit - there's no way an arbitrary model can reasonably model the current consumption (and hence power) of an opamp.

    For example, in this model, there's no current flow from the supply pins that is modelled. So if you were to take the simple approach of measuring the current into the supply and multiplying that by the supply voltage, you'd get a power of 0. There is also a mechanism in VerilogA where you can use the $pwr(powerValue) system task to output the power used by that model - although that hasn't been used in this model. You could take a copy and add a call to $pwr to do that.

    The current consumption will depend upon the implementation, as I mentioned. It would depend on the quiescent current in the amplifier, which would be mostly due to the current mirrors in the design (of course there may be other places current is drawn) - and that will depend upon how much current each of these is drawing. You'd have to model that in some way (maybe as simply as using $pwr) so that the model can then be used in a testbench where you're measuring power.

    Regards,

    Andrew.

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