  Forum Pages: 1 Limits of Phase noise L(f) = Sphi(f)/2 (Read 1821 times)
 deba Community Member   Offline Posts: 84 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 IP Logged
 Ken Kundert Global Moderator     Offline Posts: 2294 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 IP Logged
 deba Community Member   Offline Posts: 84 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 IP Logged Pages: 1