Rf power amplifier design

In my another design...after fabrication , I got parameters as follows:

S11 = -0.6779dB
S11(Ω)= 43.5-j233.7 Ω

S21= +19.36 dB (gain)
S12= -28 dB

S22 = -20.31 dB
S22 (Ω)= +49.2+j9.8 Ω

The Problem is that , the gain is received at 0 dBm but as i increase the input power level to its rated input at 20 dB from source , the expected output from this is about 40 dBm.

the device for the mention model is 25 watts (45 dBm)


but it get saturated at 36 dBm.

As per my perception, i feel that as the input return loss is very poor in imaginary part,
most of the power is reflected back to the source from the input of the amplifier.


Kindly let me know and suggest , whether i am correct? then how to design the compensation network for the imaginary part of the impedance.


if not then what may be the cause.
and then how to resolve that .



thanking you

Hi, the problem is the 1dB compression point. This point is overtaken so your gain decreases.
Bye

There are numerous plausible explanations for gain compression for a device without matching networks, with the most likely one being that the conduction angle is decreasing. To get optimal performance, expect to do load and source pull simulations, possible with harmonic load pull.

Hi,

Well, you have to match the input by adding a self of 233.7 Ω. But it depends on you passband. If you have a narrow band a self alone could be sufficient. Another parameter is your central frequency. Your inductor has to have the higher self resonant frequency.

Bye