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Image Rejection of IQ mixer

itos

What is the easiest way to simulate image rejection of an I/Q downconversion mixer - if possible with pss/pac?

Suppose the mixer is a black box with a PORT at the LO input (which generates 0 and 90 degree versions), a PORT at the RF input and two baseband outputs.

I can now use pss with the LO as beat frequency and set pac=1 for the RF input port.

With PAC I am sweeping from LO to LO+someOffset .... which makes a tone at the upper sideband. After downconversion, I should get signal energy in both I and Q channels.

In MATLAB (or a measurement) I would look at DFT(bb_i + j*bb_q) and read off the difference between the upper and lower sideband peaks. But in Spectre I am confused: I can use dB20(leafValue(mag(v("/vodi" ?result "pac")) "harmonic" -1)) and dB20(leafValue(mag(v("/vodq" ?result "pac")) "harmonic" -1)) to get the pac outputs but they are somewhat already in frequency domain. How do I combine them properly to read off the image rejection?

Or is there an easier way altogether?

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