Designer’s Guide Community

‹ Previous topic | Next topic ›

Pages: 1

Question on phase noise Sphi and normalized noise power L (Read 2335 times)

seekconfessor

New Member

Offline

Posts: 4

Question on phase noise Sphi and normalized noise power L
Feb 16^th, 2016, 5:47am

Referring to the paper "Predicting the Phase Noise and Jitter of PLL-Based Frequency Synthesizers", the normalized single-sideband noise power L and the phase noise Sphi has the relationship: L=Sphi/2. But I have some confusion on these two parameters.
Question 1: when we are talking about a VCO's phase noise , i.e. -95dBc/Hz@100kHz off, this value means L or Sphi?
Question 2: The spectre's Pnoise simulation of a VCO circuit can get a phase noise result, this result means L or Sphi?
best regards.

IP Logged

Ken Kundert

Global Moderator

Offline

Posts: 2384
Silicon Valley

Re: Question on phase noise �Sphi and normalized noise power L
Reply #1 - Feb 16^th, 2016, 1:40pm

The answer is in the units. L is a normalized noise. The units you give are dBc, which is the noise power normalized to the carrier power. If the units in dBc it's L.

The phase noise function in ADE is misnamed. It is really the normalized noise. It makes no effort to extract the phase noise. It it the total SSB noise power relative to the carrier power. However, if you apply it to the output of an oscillator at a frequency where the phase noise dominates, you get what you want.

-Ken

IP Logged

seekconfessor New Member Offline Posts: 4	Re: Question on phase noise �Sphi and normalized noise power L Reply #2 - Feb 17^th, 2016, 7:27am I've got the points, Thanks for your reply.
Back to top	IP Logged

Pages: 1

‹ Previous topic | Next topic ›