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Simulators >> Circuit Simulators >> Two Calculator Functions -- rmsNoise and spectralPower
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Message started by ywguo on Oct 5^th, 2009, 8:42pm

Title: Two Calculator Functions -- rmsNoise and spectralPower
Post by ywguo on Oct 5^th, 2009, 8:42pm

Hi Guys,

I try to caluclate SNR of a DAC output in Cadence Calculator. Can you please explain the two Calculator functions?

Quote:

rmsNoise -- Computes the integrated root-mean-square of the total output noise over the bandwidth specified in hertz in the From and To fields.This function is available only in the SKILL mode.

Is this function for AC signal only?

Quote:

spectralPower -- Plots the spectral power for the specified current waveform and voltage waveform. This function is available only in the SKILL mode.
Current waveform is the current waveform for which you which you want to calculate the spectral power.
Voltage waveform is the voltage waveform for which you which you want to calculate the spectral power

Why does this function needs two argument, voltage and current? How does it culculate the spectral power?

Best Regards,
Yawei

Title: Re: Two Calculator Functions -- rmsNoise and spectralPower
Post by Andrew Beckett on Jan 3^rd, 2010, 3:33am

Yuwei,

Rather late reply, but for the record...

rmsNoise uses the results from a noise analysis, and computes the root mean square of the noise output.

spectralPower this needs both the current and the voltage (so it can compute the power, it needs both the voltage and current, since this is coming from an AC analysis). It calculates 0.5*real(V*conjugate(I)) .

Regards,

Andrew,