The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Jul 17th, 2019, 1:34am
Pages: 1
Send Topic Print
Limits of Phase noise L(f) = Sphi(f)/2 (Read 1545 times)
deba
Community Member
***
Offline



Posts: 83

Limits of Phase noise L(f) = Sphi(f)/2
Mar 23rd, 2017, 2:43am
 
Hi,

The phase noise L(f) is defined as
L(f) = Power in 1 Hz at offset (Fo+f)/Power of fundamental(Fo). This equation is in Voltage domain. If one consider small angle approximation for phase than, L(f) = Sphi(f)/2, where Sphi(f) is the single sided PSD of phase. Under what conditions, L(f) is not equal to Sphi(f)/2. In other words, if a voltage spectrum of clock is given, in which region does one can apply L(f)=Sphi(f)/2?

Thanks
Back to top
 
 
View Profile   IP Logged
Ken Kundert
Global Moderator
*****
Offline



Posts: 2177
Silicon Valley
Re: Limits of Phase noise L(f) = Sphi(f)/2
Reply #1 - Mar 23rd, 2017, 6:48pm
 
This is discussed in Introduction to RF Simulation and its Application, in the section on oscillator (3.2). Basically, the approximation breaks down at very low frequencies (at frequencies less than the linewidth if flicker noise is neglected). Generally these frequencies are so low as to be uninteresting to designers.

-Ken
Back to top
 
 
View Profile WWW   IP Logged
deba
Community Member
***
Offline



Posts: 83

Re: Limits of Phase noise L(f) = Sphi(f)/2
Reply #2 - Mar 24th, 2017, 4:11am
 
Hi Ken,

Thanks for the reference.
Back to top
 
 
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2019 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.