pcardoso73
Junior Member
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Posts: 25
Portugal
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Dear all,
I am designing a VCO (quartz crystal at 80 MHz). I would like to do Phase-Noise/Jitter simulation, but the results are not coherent.
1 - In PNOISE should I choose FM or PM type of measurement ? If I choose PM, the "Threshold Value" should be set to Vpeak / 2 (where the zero crossings occur), right ?
2 - If I choose "Crossing Direction" to all, that means that I will have the jitter on the rising and falling edges. How does this work ? Can I calculate the jitter for both edges ?
3 - A completely different subject. I am simullating, both in weak and strong inversion. I thought that exponential law of the weak inversion would reduce 1/f noise, and thus the upconversion. I get a better plot of Phase-noise but worse values of jitter. Especially when I approach the harmonic. Please see the attached picture. Basically I have a very small harmonic, and when calculating the Jcc, its value keeps constant until I get close to the harmonic. I seems there is no contribution from 1/f^3 noise. Please notice that I did a FM simulation not PM. And the integration limits from 1 - 80 MHz (Crystal's frequency).
Best regards, Pedro
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