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Measurements >> Phase Noise and Jitter Measurements >> PSS converg. error on adding capacitor unit to cap-bank in Ring oscillator
https://designers-guide.org/forum/YaBB.pl?num=1488863914

Message started by subtr on Mar 6^th, 2017, 9:18pm

Title: PSS converg. error on adding capacitor unit to cap-bank in Ring oscillator
Post by subtr on Mar 6^th, 2017, 9:18pm

I have a pseudo differential ring oscillator (where there are two ring oscillators with coupling creating a differential output) in the output of which I have a few capacitor banks to change frequency. If I had just connected 3 LSB banks, I see no issue with convergence. But the moment I add the next bits corresponding the higher cap values, I see that the pss does not converge. Anyone has faced any similar error where a unit in capacitor bank caused a pss convergence failure.

Title: Re: PSS converg. error on adding capacitor unit to cap-bank in Ring oscillator
Post by Ken Kundert on Mar 8^th, 2017, 9:51am

Are you sure the two oscillators are oscillating as one? Are the waveforms truely periodic?

-Ken