PLL Phase margin - RF Cafe Forums

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Noise
Post subject: PLL Phase margin Posted: Sun Oct 14, 2007 6:42 am

Captain

Joined: Tue May 02, 2006 4:59 am
Posts: 15
Hi all,

I am looking for good explanation about phase margin and its relation
to PLL stability.
Why 45 degree is optimum ?

Thanks in advance,

Noise

Top

IR
Post subject: Posted: Tue Oct 16, 2007 12:14 am

Site Admin

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Phase margin of 45 deg. is a good compromise between the lock time of the loop and an adequate loop stability.

Phase margin is defined as 180deg minus the phase of the open loop, at the frequency of the loop bandwidth.

For detailed explanation about phase margin and other PLL related topics, you can read in the following line:

http://www.national.com/appinfo/wireles ... nbook.html

Posted 11/12/2012