The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> RF Design >> CHG PUMP UP/DN current mismatch in synthesizer
https://designers-guide.org/forum/YaBB.pl?num=1305697523

Message started by neoflash on May 17^th, 2011, 10:45pm

Title: CHG PUMP UP/DN current mismatch in synthesizer
Post by neoflash on May 17^th, 2011, 10:45pm

Frequency synthesizer suffers from higher spur level when CHGPMP up down current is not exactly the same. The mismatch distorts the transfer function of the PFD/CP and cause non-linearity.

I have ever heard that some people utilized a special type of PFD to solve this problem. Can people point me to the reference or describe the idea briefly?

Thanks,
Neo

Title: Re: CHG PUMP UP/DN current mismatch in synthesizer
Post by loose-electron on May 18^th, 2011, 5:54pm

if it is just a current mismatch, then the problem is no big deal - you get a higher current for pump up or down, changing the BW response characteristic a little.

When you are talking spectral spurs, thats a different issue.