hw to introduce phase distortion in the Rf signal ?

hw to introduce phase distortion in the Rf signal ?

Actually, i want to measure EVM introduce by my Power Amplifier. i have tried by driving my PA into compressing region but its Rms EVM value is 0.5% only.
so, i think there is some problem in measuring so i want to introduce Phase distortion and measure EVM ?

Thanks,
Dhaval Patel

Pre-distortion circuits gives the AM to AM and AM to PM.
I guess the driver amplifier for your PA is not driving sufficiently. Check the same for 3dB compression