Levels of the harmonic products in an RF power amp

[moondoggy]

Hello,
I am interested in the relative levels of the harmonic products in an RF power amp. My understanding is that the fundamental signal applied will increase linearly (in a non-saturated amp). Is this also true of the 2nd harmonic (assuming a wide band amplifier)? I know the two-tone intermods have 2/3 dB increase for each dB of tone increase, but I am just speaking of the actual harmonic distortion of the amp itself.
TIA

 

[xxyyuu]

Power Amp Harmonics

"two-tone intermods have 2/3 dB increase for each dB of tone increase"
I think this is wrong ，It should be that
two-tone intermods will have 2dB increase
for each dB of tone increase.
Is it right ?

 

[flatulent]

Re: Power Amp Harmonics

When amplifiers are operated in large signal mode, the intercept point method has poor accuracy. You have to make measurements on the exact circuit.

In general, the government regulations are strict enough that even class A RF power amplifiers have to have filtered outputs.

 

[moondoggy]

Re: Power Amp Harmonics

Thanks. I probably should have left out the two-tone info, because what I'm really concerned about is the amp 2nd harmonic. If I put in a 1GHz signal there is a signal also at 2GHz from the amplifier distortion. If I then increase the 1GHz signal 10dB (assuming no saturation), will the 2GHz signal increase 10dB as well?

 

[flatulent]

Re: Power Amp Harmonics

Generally, the harmonics will increase more than the fundamental as the input level is increased..

 

[icfarmer]

Re: Power Amp Harmonics

The relative harmonics is not sure for different kinds of PA. From my experience,it is relative constant for a two-stage CDMA PA.