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How to get back clean fc (Read 3245 times)

merican New Member Offline Posts: 2 malaysia	How to get back clean fc Oct 15^th, 2006, 10:02pm Greetings, I have a question here....Let say I am receiving modulated RF signal.....between the LNA and Mixer, is there any way or method that I can get back the unmodulated RF ( clean fc) ? Usually we want to retreive the modulation but in this case, I need the clean fc back. Appreciate if anybody can guide me on this. Thanks, merican
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ACWWong

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Posts: 539
Oxford, UK

Re: How to get back clean fc
Reply #1 - Oct 17^th, 2006, 10:17am

i don't think an "easy way" exists.

On the bench you can pass the signal into a extremely high Q filter (off chip SAW or Cavity resonator, or onchip MEMS or BAW etc.) to strip off the modulation....
Circuit wise you could perhaps recover the carrier frequency in a CDR (clock data recovery) which would require you to divide the rf signal frequency down, pass it into a pll with appropriate phase detector/bandwidth in a hopeful ? attempt to strip off the modulation, then vco will now oscillate at clean RF...

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merican New Member Offline Posts: 2 malaysia	Re: How to get back clean fc Reply #2 - Oct 19^th, 2006, 6:17am HI ACWWong, Thanks for the tips.....so it seems that no easy way for that. Anyway, for the purpose of discussion, can we use phase shifter to get the fc back? Or is it will cancel the RF signal itselh. Regards, merican
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ACWWong Community Fellow Offline Posts: 539 Oxford, UK	Re: How to get back clean fc Reply #3 - Oct 19^th, 2006, 6:54am hmm... i don't think so ... what is the modulation type ? why do you want the fc anyway?
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