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 Phase noise measurement from equipment is USB or DSB? (Read 11291 times)
 supermoment Senior Member Offline Posts: 167 Phase noise measurement from equipment is USB or DSB? May 20th, 2010, 11:21pm   The default/typical plot from cadence is the USB noise (upper side band), which is 3dB lower than double side band (DSB) phase noise. typical plot -->(direct plot ->pnoise analysis->function: phase noise)May I know the measure we get from RF equipments is USB or LSB or DSB?? I am new to RF stuff. Back to top IP Logged
 pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless Re: Phase noise measurement from equipment is USB or DSB? Reply #1 - May 21st, 2010, 3:04am   supermoment wrote on May 20th, 2010, 11:21pm:May I know the measure we get from RF equipments is USB or LSB or DSB?? Measurement by spectrum analyzer having simple phase noise measurement option is USB.Measurement by special equipment is PM noise.See the followings.http://www.designers-guide.org/Forum/YaBB.pl?num=1050465395/22#22http://www.designers-guide.org/Forum/YaBB.pl?num=1256925601/4#4 Back to top IP Logged
 supermoment Senior Member Offline Posts: 167 Re: Phase noise measurement from equipment is USB or DSB? Reply #2 - May 21st, 2010, 3:44am   a bit confuse after reading the thread. Per my understanding1. Phase noise is a combination of PM noise and AM noise. PM noise dominates in close in region (low freq in dBc) while AM noise usually dominates high-freq noise. 2. PM noise can be more than 0dBc in low freq 3. the typical phase noise we got from cadence is USB. (which is already consists of both AM & PM noise, whichever is the worst)4. spectrum analyzer can measure "output phase noise". However cannot measure PM noise correctly near to low freq. Thus see flat region. 5. Special equipment can do the task (measuring close in noise correctly or PM noise) Hopefully it is correct :p Back to top IP Logged
 pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless Re: Phase noise measurement from equipment is USB or DSB? Reply #3 - May 21st, 2010, 3:48am   supermoment wrote on May 21st, 2010, 3:44am:4. spectrum analyzer can measure "output phase noise". However cannot measure PM noise correctly near to low freq. Thus see flat region. Not correct.Simple measurement by Spectrum Analyzer is no more than C/N0.See http://www.designers-guide.org/Forum/YaBB.pl?num=1241917016supermoment wrote on May 21st, 2010, 3:44am:3. the typical phase noise we got from cadence is USB. (which is already consists of both AM & PM noise, whichever is the worst) See http://www.designers-guide.org/Forum/YaBB.pl?num=1260521995supermoment wrote on May 21st, 2010, 3:44am:1. Phase noise is a combination of PM noise and AM noise. PM noise dominates in close in region (low freq in dBc) while AM noise usually dominates high-freq noise. Not correct. It has to be "Normalized Output Sideband Noise". Back to top IP Logged
 supermoment Senior Member Offline Posts: 167 Re: Phase noise measurement from equipment is USB or DSB? Reply #4 - May 21st, 2010, 3:59am   I used the wrong word.. correction here:4. spectrum analyzer can measure "Voltage phase noise" or Sv. However cannot measure PM noise correctly near to low freq. Thus see flat region. Voltage phase noise = SvPhase noise =Sphi  (I shall call it: truly phase noise)refering to http://www.designers-guide.org/Analysis/rf-sim.pdf (pg12) Back to top IP Logged
 pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless Re: Phase noise measurement from equipment is USB or DSB? Reply #5 - May 21st, 2010, 4:01am   supermoment wrote on May 21st, 2010, 3:59am:4. spectrum analyzer can measure "Voltage phase noise" or Sv.. Still you are wrong.It is no more than "Voltage Noise". It is not "Voltage Phase Noise".Correctly we call it "Sideband Voltage Noise" or "Normalized Sideband Voltage Noise".Here we don't include any "Phase" term in it. Back to top IP Logged
 supermoment Senior Member Offline Posts: 167 Re: Phase noise measurement from equipment is USB or DSB? Reply #6 - May 21st, 2010, 4:21am   ok wrong againit is called sideband voltage noise=Svwhich consist of both amplitude and phase noise components. Back to top IP Logged
 pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless Re: Phase noise measurement from equipment is USB or DSB? Reply #7 - May 21st, 2010, 4:35am   supermoment wrote on May 21st, 2010, 4:21am:it is called sideband voltage noise=Svwhich consist of both amplitude and phase noise components. Correct.See http://www.designers-guide.org/Forum/YaBB.pl?num=1050465395/14#14 Back to top IP Logged
 Mayank Community Fellow Offline Posts: 334 Re: Phase noise measurement from equipment is USB or DSB? Reply #8 - Jun 29th, 2010, 9:09pm   Also, Quote:2. PM noise can be more than 0dBc in low freq Phase Noise can never be more than 0 dBc coz it means that noise present is more than the carrier itself. On the other hand, Lphi (which is a small signal approximation of phase noise b/w osc. linewidth & Fosc/2 ) can go above 0 dBc below corner freq.But true Sphi wont. As per my understanding, none of the simulators can solve true Sphi correctly for very low frequencies. What i still wonder is if it's due to lack of proper gaussian flicker noise model in technology models OR is it due to simulator's inability to solve gaussian noise in low-freq. as opposed to Lorentzian after linewidth. Back to top IP Logged
 pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless Re: Phase noise measurement from equipment is USB or DSB? Reply #9 - Jul 18th, 2010, 3:22am   Mayank wrote on Jun 29th, 2010, 9:09pm:On the other hand, Lphi (which is a small signal approximation of phase noise b/w osc. linewidth & Fosc/2 ) can go above 0 dBc below corner freq.But true Sphi wont. Wrong.I don't know what you mean by Lphi.But in actual Measurement using Actual Instruments, LSSB(f)=C/N0 never go above 0dBc/Hz but SΦ(f) can go above 0dBrad/Hz.On the other hand, in simulation using current EDA Tool, LSSB(f) could go above 0dBc/Hz at low offset especially in the presence of 1/f noise.Mayank wrote on Jun 29th, 2010, 9:09pm:What i still wonder is if it's due to lack of proper gaussian flicker noise model in technology models OR is it due to simulator's inability to solve gaussian noise in low-freq. as opposed to Lorentzian after linewidth. No.It is simply due to a limitation of small signal analysis.See http://www.designers-guide.org/Forum/YaBB.pl?num=1263835149/6#6 Back to top « Last Edit: Jul 18th, 2010, 11:14am by pancho_hideboo »     IP Logged
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