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question about polyphase filter (Read 5141 times)

aaron_do

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Re: question about polyphase filter
Reply #15 - Jul 11^th, 2007, 3:10am

hmm...i can't really figure it out. Your VCO output seems a little distorted by maybe that's just my eyes. Perhaps you could use the calculator to do FFT on the VCO output and the polyphase output to see the spectrum. Also for the PPF AC analysis, i meant you should observe the phase of all 4 outputs and make sure they have a 90 degree difference at the operating frequency.

I am not really an expert on VCO design...hope you can figure it out.

Aaron

there is no energy in matter other than that received from the environment - Nikola Tesla

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James Bond Community Member Offline Posts: 82	Re: question about polyphase filter Reply #16 - Jul 11^th, 2007, 4:43am Hi, ACWWang and aaron_do, I think I solve the problem. It's because of vco output is distorted too much. Now I retune the varactor and transistor to reduce the distortion, the ouput at the polyphase filter looks much better than before. curve8:
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