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Measurements >> Phase Noise and Jitter Measurements >> Phase Noise Measurement of Free Running VCO using Agilent Spectrum Analyzers
https://designers-guide.org/forum/YaBB.pl?num=1246922119

Message started by SiValley_designer on Jul 6^th, 2009, 4:15pm

Title: Phase Noise Measurement of Free Running VCO using Agilent Spectrum Analyzers
Post by SiValley_designer on Jul 6^th, 2009, 4:15pm

Can somebody explain the difference between phase noise measurements using Agilent E5505a and E4446b or in general 55xx vs 44xx series.

I understand that 44xx series are spectrum analyzers but there is the additional option for phase noise measurement software, which supposedly will do the job.

I have a free running VCO at 20GHz and want to measure its phase noise. Will it work out fine if I use one of Agilent Spectrum analyzers?

Title: Re: Phase Noise Measurement of Free Running VCO using Agilent Spectrum Analyzers
Post by SSA@A on Aug 20^th, 2009, 8:06pm

Spectrum analyzer can not separate Phase Noise and AM noise. the phase noise measurement option is showing the spectrum with log x-scale.

When you measure the phase noise of the free-running VCO, you need to check your instrument can track the frequency drift of carrier frequency, and also the sensitivity of high offset frequency.
In many case, the spectrum analyzer can not track the free-running VCO and shows the strange measurement result at close-in offset frequency.

If you have the E5500 phase noise measurement system, I recommend to use it. And if you plan to find new solution, I recommend the E5052B signal source analyzer.
To measure the phase noise, PLL method or Discriminator method is used. To measure the free-running VCO, you need to use the discriminator method because the PLL can not track the drifty signal source. In the E5052B, heterodyne digital discriminator is available and you will be able to measure the phase noise by just connecting the DUT. To capture 20GHz, you need to add the E5053A downconverter.

For more detail, please refer to following Agilent app notes.
“E5052B Technical Overview: See how easy it is to characterize a free running VCO”
http://cp.literature.agilent.com/litweb/pdf/5989-5040EN.pdf
“Agilent E5052B Signal Source Analyzer Advanced Phase Noise and Transient Measurement Techniques”
http://cp.literature.agilent.com/litweb/pdf/5989-5131EN.pdf

Title: Re: Phase Noise Measurement of Free Running VCO using Agilent Spectrum Analyzers
Post by SSA@A on Jun 13^th, 2011, 8:10pm

Update.
When you measure mmWave signal, please refer to this app note.
This solution will be the best one for VCOs for 77-GHz automotive radar.

"E5052B/E5053A Technical Overview: Fast and Simple Phase Noise Measurements in mmW"
http://cp.literature.agilent.com/litweb/pdf/5989-8372EN.pdf

Here's a product web-site.
http://www.agilent.com/find/ssa

Title: Re: Phase Noise Measurement of Free Running VCO using Agilent Spectrum Analyzers
Post by mobil on Aug 7^th, 2011, 9:00pm

SSA@A wrote on Jun 13^th, 2011, 8:10pm:

Thanks SSA. Could you explain more about PLL method and Discriminator method? Now we have a free-running VCO @ 30 GHz, which equipment do you recommend to measure?

Title: Re: Phase Noise Measurement of Free Running VCO using Agilent Spectrum Analyzers
Post by SSA@A on Aug 7^th, 2011, 9:31pm

Hi mobil and All

You can find the explanation about the difference between the PLL method, the discriminator method and the heterodyne (digital) discriminator method on the app note “Agilent E5052B Signal Source Analyzer Advanced Phase Noise and Transient Measurement Techniques”
I'm sorry, but I did introduce the wrong link in my first message.
Here's a correct one. please refer to this document.
http://cp.literature.agilent.com/litweb/pdf/5989-7273EN.pdf

Which method is the best for you, will depend on the drift speed.
I recommend you to contact Agilent. Agilent will offer you the E5052B SSA, E5053A downconverter and 11970A harmonic mixer for your evaluation. The SSA can support both the PLL method and the heterodyne (digital) discriminator method, so you can fonfirm the best method for your VCO.

Title: Re: Phase Noise Measurement of Free Running VCO using Agilent Spectrum Analyzers
Post by mobil on Aug 8^th, 2011, 11:31pm

Thanks SSA. Your information is quite useful. I think the E5052B is suitable for my VCO measurement.

But still I don't know how to observe the free-running VCO drift speed. What the spectrum analyzer shows close to the carrier frequency (like setup the span=2 MHz), is the flat curve. Is that caused by frequency drifting? Thanks.

Regards,

Mobil