•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe™

Sitemap

Impact of Noise Figure on Phase Noise - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


 Post subject: Impact of Noise Figure on Phase Noise
Posted: Fri Jul 22, 2005 3:03 pm 
Lets say you have a signal at a known frequency with a known amount of phase noise, and you pass the signal through a fixed attenuator, is there a way to calculate/estimate what impact the attenuation has on the phase noise of the output signal?


 
  
 
 Post subject:
Posted: Sun Jul 24, 2005 11:30 am 
 
Site Admin
User avatar

Joined: Sun Aug 03, 2003 2:02 pm
Posts: 653
Location: Erie, PA
Greetings crg:

My guess is that the effect of the attenuator on phase noise would be similar to the intended signal and noise. You would need to perform a cascade analysis for the path where the phase noise is first injected and treat that component of the total signal as a separate signal that is summed with the intended signal.

The discrete phase noise component would be attenuated by an amount equal to the total Gain in the path from the phase noise injection point and the continuous phase noise component would be subject to the total Gain and Noise Figure.

If the phase noise is present on the signal at the system input, then it is treated to the same effects as the rest of the intended signal and noise.

If it is injected in an LO at a mixer, then the phase noise component is determined by a separate cascade comprised by the path the LO signal takes.

In the last case, for a real system the summation of the two components [(intended signal + noise] + [LO + phase noise)] would be a point-by-point vector addition, so a simple scalar summing could produce erroneous results.

Any comments by others?

_________________
- Kirt Blattenberger :smt024
RF Cafe Progenitor & Webmaster




Posted  11/12/2012
Custom Search
More than 10,000 searchable pages indexed.

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger... single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website