can someone tell me how to calculate jitter .i have simulated a pll in cadence.now i need to calculate the various jitter metrics (long term jitter etc).also if there is a method to remove the ripple in the vco control voltage due to the up and down signals (the up and down keep going high for a short time even when the pll is locked),then is it a good work or should they be allowed (razavi's chapter on pll's says up and down signals going high for a short time reduces the dead band when pll is in lock).
i think instead of going in for a behavioral model.in spectre if u plot the eye-daigram,for the time when the pll has acquired lock to the end of the transient simulation time then u can use the information to calculate long term jtter etc.
if the vco is implemented as CMOS ring oscillator, I think 50ps p2p is too difficult.
if the vco is implemented as LC oscillator , maybe the phase noise of clock can be reduced. that's my opinion. hope it helps.
I am interested in how to calculate p2p or rms jitter by the eye-diagram plot? Could you give us more details about it.
I am also working on the design of PLL, but wonder how to calculate the jitter.
I dont think you can calculate jitter using simulation. You can only estimate using models (Hajimiri or Razavi) by introducing major noise source (VCO noise & supply noise). And it is not easy to get 50ps c-2-c jitter using CMOS ring oscillator.
yes that is true to a certaion extent.if u want to estimate the real time performance of the pll then u need to use these equations in those papers to characterize jitter due to vco.
I have a PLL diesign with a ring oscillor (CMOS) already in place. I want to put a regulator to reduce supply noise to VCO. What regulator configuration should i use? I cant have much voltage drop on the regulated voltage so that my VCO works correctly. I cant use use an LDO since i cant use an external CAP for compensation. Please suggest.
Can u suggest some reading for this?
Added after 49 minutes:
to add to above, the VCO runs at 800Mhz and the power supply is 3.3V