The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Measurements >> Phase Noise and Jitter Measurements >> how to get jitter for logic gates
https://designers-guide.org/forum/YaBB.pl?num=1224540840

Message started by youchen on Oct 20^th, 2008, 3:13pm

Title: how to get jitter for logic gates
Post by youchen on Oct 20^th, 2008, 3:13pm

1. Hi, I had tried to characterize the jitter for driven logic gates (for insance, a simple inverter) due to intrinsic device noise. According to Ken Kundert's paper - An Introduction to Cyclostationary Noise, there are three approaches to do that (on page 38). The first approach needs to determine the instantaneous noise power at the time of threshold crossing time. It is written that "SpectreRF can do this", but I wonder what SpectreRF analysis can do this.

2. On the other hand, I had used 'pnoise' for this purpose, but 'pnoise' gives the time-average of the noise at the output of the circuit in the form of a spectral density versus frequency, according to the reference guide. I was wondering how to convert the resulting noise spectrum to actual time-domain jitter?

Thanks.

Title: Re: how to get jitter for logic gates
Post by neoflash on Oct 30^th, 2009, 1:25pm

You should use pnoise and get phase noise output. Then integrate it over the band.

Title: Re: how to get jitter for logic gates
Post by Frank Wiedmann on Nov 2^nd, 2009, 1:14am

Please see the thread starting at http://www.designers-guide.org/Forum/YaBB.pl?num=1224609785. In general (that is without any additional assumptions), it is not possible to calculate jitter from the time-averaged noise.

Title: Re: how to get jitter for logic gates
Post by love_analog on Apr 20^th, 2010, 7:59am

Another thing I would like to add on. I understand your question is mostly about thermal noise induced jitter. However, typically most of the jitter will come from power supply noise so please don't forget that.

Best way is to put say 50mV pp sinewave at a non-multiplier ratio of the reference frequency and look at the pp of the output.