Ken Kundert wrote on Aug 16^th, 2006, 12:21am:


I'm currently designing a mosfet ring oscillator for a University project and trying to get my head around phase noise for the first time. In patricular, what exactly Cadence ADE is generating for me. Like many, I was initially stumped by the positive PN plot at low offset frequencies.

Have a better understanding now thanks to the following discusions:
designers-guide.org/Forum/YaBB.pl?num=1155691089
designers-guide.org/Forum/YaBB.pl?num=1050465395
designers-guide.org/Forum/board=jitter;action=display;num=1036525104

However, my main concern is how to deal with this low frequency corner. How do I determine the minimum offset frequency for which my phase noise plot generated by ADE is accurate?


Aditionally, the Cadence software provided at my university is some kind of beta version IC6.1.1.500. Interestingly its actually plotted a Corner frequency (image attached). How do I interpret this corner frequency? All the Uni's documentation is for the previous release?


And finally, does Cadence ADE/SpectreRF report rms period jitter?


Many thanks in advance,
Dave.



Uploaded image to drop.io/switch7/asset/pn-plot, PN_plot.png.
(Would not upload 48kB attachment here: An Error Has Occurred! 3873 kilobytes and cannot be uploaded. ??)