The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> RF Design >> supply noise's influence on PLL
https://designers-guide.org/forum/YaBB.pl?num=1584501186

Message started by tulip on Mar 17th, 2020, 8:13pm

Title: supply noise's influence on PLL
Post by tulip on Mar 17th, 2020, 8:13pm

In ADI's Analog Dialogue 45-09, "Power Management Deisng for PLLs“
it says, "Within the PLL's loop bandwidth, the PLL can successfully track and filter the LDO noise, reducing its contribution."


My question is :
what is "the track and filter" main in the conclusion : "Within the PLL's loop bandwidth, the PLL can successfully track and filter the LDO noise, reducing its contribution."


Thank you.

Title: Re: supply noise's influence on PLL
Post by smlogan on Jun 2nd, 2020, 1:44pm

Dear tulip,

> what is "the track and filter" main in the conclusion : "Within the PLL's loop bandwidth, the PLL
> can successfully track and filter the LDO noise, reducing its contribution."

The phase of the output clock of a phase-locked loop will follow the phase of its input reference clock when the frequency of its phase disturbances are less than the bandwidth of the phase-locked loop. Hence, the statement from Analog Device's Analog Dialogue indicates that as long as the phases disturbances of the LDO has frequency components less than the bandwidth of the phase-locked loop, the phase-locked loop will attenuate phase disturbances due to the LDO.

Does this help tulip?

smlogan

The Designer's Guide Community Forum » Powered by YaBB 2.2.2!
YaBB © 2000-2008. All Rights Reserved.