James
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snowfiled
Posts: 32
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Hey Ken, Thanks for your reply. I did the simulation as you indicated in your last post. 1. My divider is a 1/8 ripple divider. As you wrote in your paper, I should only simulate one stage at one time. My input frequency is 200MHz. So after the fist stage, the frequency should be 100MHz. 2.I set the beat frequency 100MHz in PSS form. In the pnoise form. I use timedomain option and add the cross time point 0.5ns. After I finished the simulation, I could only observe the result in the "Result Browser". The unit of the pnoise result is V/sqr(Hz). Then to get the variance of output noise, I should integrate the result from 0 to f0/2(i.e. 100M/2). Here is the question: I am not sure whether I should integrated the result directly since the unit is V/sqr(Hz)? I think I should firstly change the unit from V/sqr(Hz) to V**2/Hz. To do so, after I get the date of timedomain.pnoise from the result browser, I use the X**2 button on the calculator to squre the result. Then use Integ function to integrate it from 0 to 100M/2. Then I use Eq(54) to calculate Jee. Am I right? If not, how to calculate the var(nv(tc)) with the "V/sqr(Hz)" result? 3. With the method mentioned above. I get the jitter for the first stage: about 0.2 ps. Then I suppose the other two stages have the same jitter since these stages are all same and you said jitter was independent on the input frequency. Then I calculate the total jitter by Jee= sqr(0.2**2+0.2**2+0.2**2), resulting at 0.3xx ps. Is this too small for a 1/8 divider? Thanks for your time. your explanation will be highly appreciated. Bests, James
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