gain expansion

hi everybody
I'm designing PA for 802.11b,but i find it has the problem of gain expansion, as a
result, the 1dB point is lager the normal value, in other words, the linearity is bad,
how can i solve it? thanks

I guess the PA bias is not optimum.
Try to play with bias voltage and current to suppress the gain expansion.

Thanks

Normally, gain expansion generated by Vgs modulation. Maybe you can increase the Idq to a real class A PA to see what will happen.

shunt a cap in bias circuit will be better to gain expansion