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Design >> Analog Design >> Calculating power in Cadence Spectre
https://designers-guide.org/forum/YaBB.pl?num=1164140386

Message started by sarivisetti on Nov 21^st, 2006, 12:19pm

Title: Calculating power in Cadence Spectre
Post by sarivisetti on Nov 21^st, 2006, 12:19pm

Hi
I was trying to calculate the power consumed by an instance in cadence spectre using the calculator option. I am able to get the waveform of the power and when i am clicking on the calculator->then click on wave->then take an average-> and click evaluate.....it is giving me a warning
"Evaluation error, Unknown scalar data type: nil". I am able to calculate the average voltages and currents. The problem comes only with power calculations.
Can someone please help me with this.
thanks in advance...
sarivisetti.

Title: Re: Calculating power in Cadence Spectre
Post by bernd on Nov 22^nd, 2006, 12:26am

Have you ticked in ADE "Outputs -> Save all ..." and
then "Select power signal to output == all"?
By default the button is disabled.

Bernd

Title: Re: Calculating power in Cadence Spectre
Post by sarivisetti on Nov 22^nd, 2006, 10:08am

hey,
Thanks for a quick reply.
yes I did save all the powers, like I followed the same procedure before too. But still I am not able to get the power value. its giving me the same warning message.
I really dont know what i am missing to do.
Please help.
Thank you,
Sarivisetti.

Title: Re: Calculating power in Cadence Spectre
Post by ACWWong on Nov 22^nd, 2006, 12:28pm

how are you calculating power ? what expressions are putting into the calculator ?
Are you using wavescan or AWD ?
It is much better to express your power as transient current or voltages of nets rather than waveform objects.
But if you can plot say IT("/Rout/PLUS") and VT("/out") and also plot the product, then average should evaluate.

Title: Re: Calculating power in Cadence Spectre
Post by sarivisetti on Nov 27^th, 2006, 10:21pm

hey,
Thank you for the reply. Yes, I was using the wave scan. I could get the power by taking the product of current and voltage. But was just wondering why the wavescan isn't working..Anyways Thanks a lot again for you reply.
Sarivisetti.