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Design >> RF Design >> theory of cyclostationary noise
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Message started by modern_analog on Mar 11^th, 2006, 3:16pm

Title: theory of cyclostationary noise
Post by modern_analog on Mar 11^th, 2006, 3:16pm

i understand how modulation causes a frequency upconversion/downconversion. this is the basis of LTV versus LTI analysis

The confusing thing: some papers talk about non-linearity and it causing frequency upconversion. Again that makes sense

How are the 2 related or waht is correct? Please help!!

Title: Re: theory of cyclostationary noise
Post by Ken Kundert on Mar 12^th, 2006, 2:04pm

Nonlinearity by itself does not directly result in frequency conversion. Rather, the characteristics of the circuit are modulated by the presence of a large unrelated signal such as an LO if the circuit is nonlinear. Thus, if the large signal is periodic, it acts to periodically modulate the characteristics of the circuit, characteristics like effective gain. Thus, to the information signal, which we will assume is small, the circuit appears as if it is a periodically time-varying linear circuit, and that is what causes the frequency conversion.

-Ken