Jitter function

Dear Nalaeg,

Nalaeg said:

Can anyone provide me some insights about the jitter function in Cadence (calculator)?

Which jitter does it calculate?

If you are referring to the abs_jitter() function, it computes the time interval error of a periodic waveform relative to a waveform with the period of Tnom. It is documented in the Virtuoso Visualization and Analysis XL User Guide. In the October 2022 version of the manual, it is described on pages 935 - 938. There is also document link with an example that shows how Cadence defines the measurement in the Forum post at URL:

https://community.cadence.com/cadence_technology_forums/f/rf-design/56894/jee-measurement

Look for the link to the document that contains "jee_computation_example_sml_032823v1p0.pdf". (I can no longer include the full link to the document or my response will be classified as spam - sorry!) Please refer to pages 34 - 36 for a verbal and graphical description of time interval error.

Shawn

Dear Shawn, 

Thank you very much! It was very helpful.

Dear Nalaeg,

I am just happy to read it was helpful to you - good luck!

Shawn

Hi Shawn, is it possible to get a similar document for Jc and Jcc? I want to understand how k factor effect the jitter measurement.

Context: I'm observing that if I keep on increasing the k factor in my calculator jitter keeps on increasing till 1000e3 cycles (beat frequency is 500kHz) and then becomes constant. Does it indicate a long-term jitter and requires large number of cycles to give constant STDeviation? Or my understanding is totally wrong. 

Dear HSDROP,

HSDROP said:

is it possible to get a similar document for Jc and Jcc? I want to understand how k factor effect the jitter measurement.

I took some time to assemble my understanding of the Cadence Jcc and Jc(k) definitions. I also thought an example waveform might help provide some added insight into the jitter metrics. Finally, I made an attempt to answer your question as to how the value of Jc(k) behaves as k increases and approaches the number of periods (N) of the simulation. The notes is at:

I am unable to include the actual link as it will cause my response to be classified as spam. However, if you are interested in reviewing the note, you can copy and paste the following into your browser after manually typing the prefix.

1drv.ms/b/

s!AnM-GsAEZPoSr1ymmxF5WYE75-j1?e=fwLQ3R

To save you (or anyone with an interest), I've attached the summary page 28 from the note as Figure 1.

I hope this is useful and helps address your question HSDROP.

Shawn 

Figure 1

page 28 of "Definitions of Cadence® Cycle-to-cycle Jitter Metrics Jc (k) and Jcc and Examples"