eye diagram simulation
sadfish said:
what's the different and relation ship between the jitter and phase noise?
they're two effects of the same phenomenon. Suppose to have a periodic waveform. Due to several noise sources the period won't be exactly the same at each cycle. For this reason if you analize the waveform in the frequency domain you won't see lines, but lorenz-like curves. You call this phenomenon phase-noise.
On the other hand if you analize the waveform in the time domain you will see a waveform with a period of a certain mean value T0 and a variance of deltaT^2. The variance is what you call jitter.
An approximated relationship between jitter and phase noise is:
S(deltaf)=(f0/deltaf^2)*[(deltaT/T0)^2]
where S is the phase noise, f0=1/T0 and deltaf if the difference between f0 and the frequency where you calculate phase noise. Actually the relationship is far more complicated but this is a good approximation in a large deltaf range.
sadfish said:
IN pll design, what is the main source of jitter or phase noise. the noise of device(MOSFET , R), the fluntuation of the power&gnd ?
That's a difficult to answer question. Suppose you have a PLL which is sinthesyzing a frequency f0. As i stated before you have phase noise surrounding your signals at frequencies f0+deltaf. For low values of deltaf the noise comes from the reference signal. For mean values of deltaf the noise is due to the loop filter. For high values of deltaf (usually important for adjacent channel interference) noise is due to the VCO.
Now each of these building blocks has its own noise sources which are related to the architecture and also to the layout realization of the block.
sadfish said:
Another problem is how to simulate the jitter of PLL in hspice?
How can I measure the jitter in the output of hspice simulation result? when I simulate a PLL in hspice, I want to know the long time jitter and maxim cycle to cycle jitter, what should I do?
How can I analysis the spectrum of the jitter in hspice?
sorry i have no answer for this
hope this helps