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Design >> RF Design >> mixer linearity
https://designers-guide.org/forum/YaBB.pl?num=1161406097

Message started by sivacha on Oct 20^th, 2006, 9:48pm

Title: mixer linearity
Post by sivacha on Oct 20^th, 2006, 9:48pm

can u suggest the best way to improve the linearity of a folded mixer??

by doing source degeneration the noise figure is increasing.
i have very tight constraints on noise figure and linearity.

are these inter-related??

thank you.......

Title: Re: mixer linearity
Post by aaron_do on Oct 20^th, 2006, 11:50pm

A folded mixer is just an amplifier plus a switching stage. Source degeneration will improve the amplifier linearity at the cost of noise figure and gain. You should be able to use any of the typical methods to improve your amplifier's linearity such as multiple gated transistors. Or you could use a low noise amplifier...

Another method i've seen is to use a current mode mixer followed by an IF transimpedance amplifier.

hope that helps

Aaron

Title: Re: mixer linearity
Post by ACWWong on Oct 21^st, 2006, 1:57pm

sivacha wrote on Oct 20^th, 2006, 9:48pm:

are these inter-related??

generally yes, more linear means less gain & more noise... as Aaron suggested you can try different toplogies/circuit system lineup, but the usual method to break this catch22 is to increase power ...