Amplifier class vs Compression Point

[Young_Electronic_00]

Hello All,

I've fast question, because I want to be sure about my thouths. Let we take under consideration three amplifiers working in A, B and C classes. In every case, the saturation power is the same. It will be true if I will conclude, that for A class the 1dB compression point will be the highest one and for C class will be the smallest one ? I'm considering here linearity of amplifiers, so according to this fact, difference between P_sat and P _1dB for class-A will be the smallest. I'm correct ?

Best Regards,

 

[BigBoss]

Compression Point is Independent from Class of the Amplifier.
It's essentially the Output Power where the Power Gain drops by 1dB compare to Small Signal Gain.
So, this is applied to any kind of amplifier. Class of an Linear Amplifier is related to Conduction Angle of Collector/Drain Current.

 

[Young_Electronic_00]

Thanks ! Well, so I've to find out why transfer function of my amplifier (Pout vs Pin) is not straight line in linear part of the characteristic. I thought, that the reason is behind class of this amplifier which is "B" configuration (difference between 1dB and Psat is almost 7 dBm).

 

[BigBoss]

Thanks ! Well, so I've to find out why transfer function of my amplifier (Pout vs Pin) is not straight line in linear part of the characteristic. I thought, that the reason is behind class of this amplifier which is "B" configuration (difference between 1dB and Psat is almost 7 dBm).

It's possible. C-Class and B-Class even AB-Class Amplifiers start to amplify a signal just after a certain power level. Therefore it's normal to see a ramping/knee at very small power levels. But after that the Power Gain should be constant for a region then starts to drop down. You reference has to be that region so amplification should already be started. You can assume that region as small signal.