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Design >> Analog Design >> loop bandwidth and ppm tolerance?
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Message started by casual on May 12^th, 2011, 6:14am

Title: loop bandwidth and ppm tolerance?
Post by casual on May 12^th, 2011, 6:14am

For the 1st order PI CDR, if it can tolerate until 500ppm of freq1.
Does it mean the loop bandwidth is around (500ppm/1e6)*freq1?
Is the loop bandwidth different to the ppm tolerance?

Title: Re: loop bandwidth and ppm tolerance?
Post by rfidea on May 12^th, 2011, 8:47am

What is a PI CDR?

Title: Re: loop bandwidth and ppm tolerance?
Post by casual on May 13^th, 2011, 5:28pm

PI = phase interpolator
CDR= clock and data recovery circuit

Title: Re: loop bandwidth and ppm tolerance?
Post by loose-electron on May 16^th, 2011, 5:40pm

if you want an answer here I think you need to define the question a lot more

Title: Re: loop bandwidth and ppm tolerance?
Post by raja.cedt on May 19^th, 2011, 12:03pm

loop BW: How fast it can track Phase and frequency variations.

PPM(specific to CDR): How much frequency difference that can be tracked by CDR between data and clock with out loosing lock.

For a first order CDR there is no PPM (for most of the cases), i guess you are intended to ask 2nd order CDR

PI based CDR means Phase interpolation based Clock and Data Recovery

Thanks.

Title: Re: loop bandwidth and ppm tolerance?
Post by newic on May 20^th, 2011, 6:12pm

I think the first order PI based CDR can tolerance some PPM, depending on filter setting.

For the loop BW, it is mainly determined by main loop parameter, excluding the 2nd order loop.