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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> Division ratio on PLL output spectrum https://designers-guide.org/forum/YaBB.pl?num=1207579437 Message started by northfish on Apr 7th, 2008, 7:43am |
Title: Division ratio on PLL output spectrum Post by northfish on Apr 7th, 2008, 7:43am A question confused me for quite a while: In a generic RF PLL with phase detector, Loop filter, VCO and loop divider /N, if the division ratio N is scaled down to N/2, the reference frequency is 2xfref, while ALL OTHER components are kept the same, how will the PLL output spectrum change? Close-in phase noise floor? Far-out phase noise? Please comment on it. thanks! |
Title: Re: Division ratio on PLL output spectrum Post by zwtang on Apr 10th, 2008, 9:33pm If the in-band phase noise is determined by charge pump noise, the overall in-band phase noise decrease 6dB, out-band phase noise doesn't change. zwtang 04/11/08 |
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