Dear everyone,
I encounter a problem on Origin Offset Suppression with 8PSK modulation. My transmitter is a direct up-conversion topology. Under conditions where temperature is 25 and 75 Celsius degree,  OOS is about -31dB and -35dB respectively. But under low-temperature condition with -20 Celsius degree, OOS degrades to -25dB.

I want to know which factor would dominate OOS with temperature variance, LO leakage/self-mixing or I/Q channel mismatch.

Welcome any suggestion. Thanks!

Best,
Yutao