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# Power amplifier DC Power Consumption

#### dolgaleb

##### Member level 1
I am replacing a power amplifier from a transmitter chain because it is obsolete. I would like to determine the required DC consumption for the PA so that the Power Supply Design (PSD) engineer can update his design.

Since the design is supplied by a battery, we need the PA to be efficient.

The PSD tested the old design and monitored its current to know the DC consumption. So, the measured power was 10W. He explained that all I needed to do with the Power Amplifier was to make sure that we didn’t exceed the DC consumption he measured.

I tried to find solutions that would keep the DC consumption under 10 W but I couldn’t find one that would also fit on the board. So he suggested for me to determine the DC consumption of the PA in the old design. It turns out that it was consuming 15 W. So the thinking was if the old design works with that PA consumption, then let’s look for a solution that doesn’t exceed 15 W.

I would like to know if there is way/method to determine what the consumption of the PA needs to be based on the DC consumption of the old design. It is not clear to me which method is correct and I don’t want to design for the wrong consumption.

Hi,

power consumption: as always: P = V * I

now it depends what you are after:

P(avg) = V(DC) * I(avg)

or

P(pk) = V(DC) * I(pk)

*****
Besides this we see a lot of text without useful information.
Like:
* are you talking about an audio amplifier or RF amplifier or anything else ... and what is it used for?
* what are both amplifiers exactly? Manufacturer, part number, link to datasheet
* what types are both amplifiers? Amplifier class
* What output power do you need? Is this output power continous and flat? or are there IDLE situaltions, does/can the output power vary?
* When IDELING: how long is idle, how long is full power?
* Is your power supply voltage stabilized, or is it pure battery voltage? What range (fully down to highest charging voltage)
* every other technical information we need to know..

Please give short but clear answers .... better in a table than hidden in lots of text. Numbers with units and tolerance.

Klaus