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reduce phase noise
Hi guys,
I am designing a ring VCO. When I do the phase noise simulation. I found the phase noise is not good and main contribution of phase noise is come from the
bias current, that is to say, the opamp in bandgap.
How can I filter the bias noise? I know that add a...
I got a problem when I read some paper about delta-sigma modulator in fractional-N synthesizer.
For my understanding, the input range of DSM is 0~1, because normally, N= M+k/2^K.But in some papers, it mentioned input stable range covers from 0.5 to 1.5 ( Keliu Shu, a comparative study of...
rhee high performance charge pumps
You can read these papers as reference.Hope it will be help you.
[1].J.Maneatis et al.,”Self-Biased High-Bandwidth Low-Jitter 1-to-4096 Multiplier Clock Generator PLL,”IEEE J.Solid-State Circuits,vol.31, pp.1795-1803,Nov.2003.
[2].Ian A.Young,”A PLL Clock...
pnoise analysis
Thanks for your suggestion.
I think we measure the current noise output from CHP is right.But I can not set the output as current when do pnoise analysis.(See pic1) .My test circuit is show in pic2. And another question is how to set the noise type?
I check the cadence...
pnoise pfd cp
I want to do the phase noise analysis of the whole PLL. And try to
get the different parts phase noise seperate.
A pss+pnoise was done for my PFD plus CHP. The inputs of the PFD is two clk which made the CHP output average current close to 0 to simulate pll lock state.
The output...
I think this is because the computing method uesed to calculate the phase noise was not accurate in low frequency.You can check the Cadence file about it.
Re: jitter in PLLs
Normally, the power supply noise are major source if your circuit have poor
PSRR.Then the VCO noise will dominate.
And how did you test your PLL? Test method is also key.Sometimes , if your
pad drive ability is not good, you can observe that the rsing time are big.It will...
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