How to specify TX jitter spec ? PLL clock jitter specs in serdes ?? 1. DJ 2. RJ ( integration range , CDR BW to Nyquist data rate ). Could u explain me in terms of PLL clock and PSIJ... Thank you Chen for helping us to understand Serdes in better way.
Thanks for the feedback. 1. TX jitter spec (like DJ & RJ (integration range, CDR BW to Nyquist data rate)) specified in every standard? I would try to make a video to describe that :) 2. PSIJ is a good suggestion, and I do the analysis all the time. I would make a video to describe that :)
Hi CC, someone asked about how SJ amplitude can be quantified in UI, I saw your answer but I still cant grasp the concept. If it's the jitter movement of the input phase which translate to eye width margin, then a SJ with 5 UI-pp is causing the eye to be so bad (closed completely), and yet we still manage to recover? Do you have any good reference or illustration on how the SJ UI can impact the eye on RX side?
Hi Beautiful, nice to meet you. Yes, even though a SJ with 5 UI-pp, the CDR could still manage to recover well as long as the frequency of the SJ is slower than the CDR BW well enough.
thank chen, a good video , I have saw the concept of '"baudrate/1667" at many place .in your video you said this is XAUI standards .I wonder why is 1667 and if it is another value in another standars?
Hi Yujan, nice to meet you. I'm glad you like it. You're correct. Most specifications specified the corner frequency as either equal to 1667 or close to it, which was considered the link partner of CDR's tracking BW. Thank you.😃
Hi Amit, nice to mee you. Thank you for the question. If I understand correct you correctly, you are asking the SJ freqeuency. Correct? If yes, the CDR's BW may be less the the nyquist frequency, then there's no filtering or tracking. So, the eye degraded eye width margin is just the modulation depth you applied at this f_Nqy SJ frequency.
@@circuitimage okay. I was studying about bang bang CDR and the JTOL looks like hockey stick, it slightly increases about reaching the lowest point, can you explain me why the tolerance would improve?
Hi Amit, good question. The lower SJ frequency means a slow movement in input jitter, then the CDR should track it well since it's within its BW. So, it's not improved, and it just the CDR can track the low freqeuncy jitter and have a bigger modulation depth (in UI) tolerance.
@@amitkhade6418 Good question. The sinusoidal jitter can be specified with amplitude and frequency.The amplitude was the peak jitter movement of the input phase (or in time in second), which also can be normalized to UI such that we can evaluate the eye width margin easily.
Good job, CC. I watched your old video, and love to see you had some new ones lately. Could you make a video about BB CDR?
Thanks for the feedback and good question. I'm glad you love it and Sure. I'll make the BB CDR.
@@circuitimage CC, is there a way I can contact you privately? email, wechat, or your LinkedIn homepage?
@@jueshi2436 www.linkedin.com/in/chung-chun-cc-chen-992b8734/
Here you go: ua-cam.com/video/gdWOQIh7frA/v-deo.html
Thanks! It’s really helpful!
Hi 沛PeiLife, nice to meet you and I'm glad that's helpful. :)
thanks you for your explain ^^
Hi dunn, you're welcome.
How to specify TX jitter spec ? PLL clock jitter specs in serdes ?? 1. DJ 2. RJ ( integration range , CDR BW to Nyquist data rate ). Could u explain me in terms of PLL clock and PSIJ...
Thank you Chen for helping us to understand Serdes in better way.
Thanks for the feedback.
1. TX jitter spec (like DJ & RJ (integration range, CDR BW to Nyquist data rate)) specified in every standard? I would try to make a video to describe that :)
2. PSIJ is a good suggestion, and I do the analysis all the time. I would make a video to describe that :)
Hi CC, someone asked about how SJ amplitude can be quantified in UI, I saw your answer but I still cant grasp the concept. If it's the jitter movement of the input phase which translate to eye width margin, then a SJ with 5 UI-pp is causing the eye to be so bad (closed completely), and yet we still manage to recover?
Do you have any good reference or illustration on how the SJ UI can impact the eye on RX side?
Hi Beautiful, nice to meet you. Yes, even though a SJ with 5 UI-pp, the CDR could still manage to recover well as long as the frequency of the SJ is slower than the CDR BW well enough.
You could refer here: ua-cam.com/video/kZExm9wy0G8/v-deo.html
Let me know if that's what you need. If not, I can send you others. :)
thank chen, a good video , I have saw the concept of '"baudrate/1667" at many place .in your video you said this is XAUI standards .I wonder why is 1667 and if it is another value in another standars?
Hi Yujan, nice to meet you. I'm glad you like it. You're correct. Most specifications specified the corner frequency as either equal to 1667 or close to it, which was considered the link partner of CDR's tracking BW. Thank you.😃
What happens if we apply frequency greater than nyquist frequency
Hi Amit, nice to mee you. Thank you for the question. If I understand correct you correctly, you are asking the SJ freqeuency. Correct? If yes, the CDR's BW may be less the the nyquist frequency, then there's no filtering or tracking. So, the eye degraded eye width margin is just the modulation depth you applied at this f_Nqy SJ frequency.
@@circuitimage okay. I was studying about bang bang CDR and the JTOL looks like hockey stick, it slightly increases about reaching the lowest point, can you explain me why the tolerance would improve?
Hi Amit, good question. The lower SJ frequency means a slow movement in input jitter, then the CDR should track it well since it's within its BW. So, it's not improved, and it just the CDR can track the low freqeuncy jitter and have a bigger modulation depth (in UI) tolerance.
How does the Amplitude of Sinusoidal jitter gets converted to UI
@@amitkhade6418 Good question. The sinusoidal jitter can be specified with amplitude and frequency.The amplitude was the peak jitter movement of the input phase (or in time in second), which also can be normalized to UI such that we can evaluate the eye width margin easily.