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Design >> RF Design >> Peak to average Power
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Message started by Nibblo on Jun 6^th, 2007, 7:16am

Title: Peak to average Power
Post by Nibblo on Jun 6^th, 2007, 7:16am

I would like to know how the peak to average power is
calculated using Cadence Spectre tools. This for a modulated signal
measured at the output. I believe a simple measure of Vrms*Irms is
not sufficient. This because the signal is a modulated signal.

A few detailed steps using the cadence calculator
would be appreciated.

Title: Re: Peak to average Power
Post by chase.ng on Jun 7^th, 2007, 8:47pm

Hi,

Peak to average power is a ratio commonly known as PAPR, definately is not Vrms*Irms. If the load is constant, then Vrms^2/R will give the average power. To calculate the peak power, use Vpeak^2/(2*R).

regards,
chase

Title: Re: Peak to average Power
Post by Nibblo on Jun 8^th, 2007, 3:32am

The two equations you specify are the same mathematically :-)

Title: Re: Peak to average Power
Post by RFICDUDE on Jun 9^th, 2007, 5:23am

For a single sinusoid the two equations are the same. This is why a CW signal is said to have a PAPR = 1 or 0 dB.
In general amplitude modulated signal have a PAPR > 0 dB, so you need to measure Vrms and Vpk as indicated in the expression (so long as you are measuring it across a load resistor R).

Title: Re: Peak to average Power
Post by chase.ng on Jun 12^th, 2007, 10:17pm

Hi RFICDUDE,

Thanks for clarifying that, guess I didn't make it clear enough at the first place. :)

Regards,
chase