Psat vs Linear Output Power

Hi,

What is the difference between the Psat output power and the linear output power when mentioned in the datasheet of a Power Amplifier? When I have to choose a PA device for 6 W output, would it be okay to choose a device with a pretty high Psat output power (like 50 W) but has a linear output power of around 8-10 W?

The difference is application specific. Some applications can stand a heavily distorted output, so you can run the amplifier fully saturated (like constant envelope modulations such as FSK). Some applications use complex modulation schemes where a little bit of output distortion destroys your ability to demodulate the data without huge bit errors (like 256 QAM)--so you need a very linear output in the amplifier.

What is your modulation plan?

Thanks for the replies. The modulation is FM. So in this case, the saturated power would be more important?

Yes, FM is FSK. And biff44 is right.
But 3dB backoff from P1dB maybe better if you want a longer product life.

Thanks for the reply...It's looking a little clearer now...thanks again.

For SSPA, there are several definitions for linear output power. For example, the output power at which IM3 is better than -25 dBc is regarded as linear power. Some people use definition from ACPR test with QPSK or OQPSK modulation. That is output power at which ACPR is better than -30 dBc.

What tony lth didnt pick up on is FM voice is very different to a FSK signal ... and you havent told us if its voice or a digital mode.
For FM voice you could run the TX in class C, its the common way. for digital modes use a linear mode like class AB etc.
Preferably you dont want to run any TX device into saturation anyway, the moment it goes into distortion its output is going to produce garbage right across the spectrum, to the ire of other users.

Dave