Why if i do a mixing circuit with sa602 when i put a dc of -200mv at the input the output is 100mv and my frequency and if i put 200mv the output is a signal at my frequency with 10uv amplitude? why is not the same amplitude but not the same phase? I am trying to do a mixing of a digital signal and an AC signal for phase modulation. Thanks a lot.
I suspect you are upsetting the bias. Below is a quote from the SA602 datasheet. This is a problem for NRZ data. Have you looked at LM1496 (NE1496, MC1496, etc.)?