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Design >> Mixed-Signal Design >> quadrature generation
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Message started by aaron_do on Sep 11^th, 2013, 8:17pm

Title: quadrature generation
Post by aaron_do on Sep 11^th, 2013, 8:17pm

Hi all,

I am designing a quadrature signal generator using a divide-by-2 circuit. As I understand it, compared to a RC phase shifter, one drawback of the div-2 IQ generator is that there is no certainty in which signal is I and which is Q. In a phase shifter, each RC provides a 90 degree phase shift, so if you assign one line to 0 degrees, you know exactly which one is -90 degrees. Whereas in a div-2 circuit, whether a line is +90 or -90 degrees depends on the initial state of the flip-flop.

So my question is, in what applications is this important? For instance, I think in a image-reject mixer, if you mix up your I and Q, you will end up selecting the wrong sideband. Are there other important applications anyone can mention?

thanks,
Aaron