carlgrace
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I am looking into switch-mode passive mixers and I've read most of the relevant papers. I am wondering, though, why isn't the output thermal noise density determined by kT/C noise of the sampling switch. It seems to me that there would be a lot of output noise because the reverse-biased diode formed my the drain diffusion of the MOS switch would sample the switch noise. This noise would be very high because the diffusion capacitance would be rather small. It seems from the papers, however, that this is not the case. Can anyone give me an intuitive explanation of why the output noise of the passive mixer isn't kT/C, where C is the parasitic capacitance of the drain diffusion?
thanks, Carl
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