Prabhu wrote on Jul 28th, 2006, 11:53pm:As Aaron says,
Is it be possible for the downconverted signal at the mixer output to mix backwards and add to the actual mixer input signal?
How can that happen?
1) There is no active source at the mixer output.
2) Also there will be no reflections since we are using lumped components in simulation.
I don't understand the two points you make, i can't see why active sources at the mixer output or lumped components make any difference to what you are observing.
I think Aaron's original explanation seems pretty good.
So (without going to quadrature mix) you should be able to decrease the relative amplitude of the unwanted tone by decreasing mixer Rs, or fiddling with the fet sizing, bias points (including back gate!) to improve the situation.