The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Jun 13th, 2021, 1:07am
Pages: 1
Send Topic Print
low BW pll loop filter (Read 5104 times)
raja.cedt
Senior Fellow
******
Offline



Posts: 1516
Germany
low BW pll loop filter
Dec 03rd, 2012, 10:25am
 
Hello,
While reading a doc from ee times, i came to know that there are few applications which require PLL bw around 10Hz, i wounder how people manage that kind of filters. The only one idea came to my mind when i read this nA charge pump current  and very low resistance. I would like to hear some implementable solution.

Thanks,
Raj.
Back to top
 
 
View Profile WWW raja.sekhar86   IP Logged
smlogan
Community Member
***
Offline



Posts: 38
Boston, MA
Re: low BW pll loop filter
Reply #1 - Apr 11th, 2013, 9:35am
 
Hi Raj,

Loop bandwidths of this magnitude are usually bulkwave quartz based. In other words, the Kvco is very low (often much less than 100 ppm/V). They are used for highly stable clocks often referred to as Stratum III or better. In some cases, the frequency varying element is non-crystalline, but also possesses an extremely low Kvco.

I hope this helps!

Shawn
Back to top
 
 

Shawn
View Profile   IP Logged
raja.cedt
Senior Fellow
******
Offline



Posts: 1516
Germany
Re: low BW pll loop filter
Reply #2 - Apr 11th, 2013, 12:39pm
 
hello thanks for the reply. Do you mean filter might be a SAW based and VCO based on crystal oscillator??

Thanks,
raj.
Back to top
 
 
View Profile WWW raja.sekhar86   IP Logged
Lex
Senior Member
****
Offline



Posts: 201
Eindhoven, Holland
Re: low BW pll loop filter
Reply #3 - Apr 12th, 2013, 2:43am
 
Go digital?
Back to top
 
 
View Profile   IP Logged
smlogan
Community Member
***
Offline



Posts: 38
Boston, MA
Re: low BW pll loop filter
Reply #4 - Apr 17th, 2013, 2:23pm
 
Hi Raj,

Sorry for the delayed response...

hello thanks for the reply. Do you mean filter might be a SAW based and VCO based on crystal oscillator??

Yes. A bulkwave quartz based oscillator (VCXO) will have a lower Kvco in general than a quartz surface acoustic wave based oscillator (VCSO). Hence, the latter is most often used in low bandwidth PLL.

Shawn
Back to top
 
 

Shawn
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2021 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.