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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> phase noise questions? https://designers-guide.org/forum/YaBB.pl?num=1241452146 Message started by liletian on May 4th, 2009, 8:49am |
Title: phase noise questions? Post by liletian on May 4th, 2009, 8:49am Hi Guys I had a measured results shows the following spectrum of ring oscillator, it seems the spectrum is dirty, any suggestions what the phase noise source might be? I do not think it is flicker noise since it is at the 10Mhz region, am I right? Also, is their paper or post about VCO layout techniques? I would like to make a PLL, but I want to isolate VCO from mixer and amplifier stage if possible. Thanks |
Title: Re: phase noise questions? Post by pancho_hideboo on May 4th, 2009, 8:53am liletian wrote on May 4th, 2009, 8:49am:
It is not suprised at all that spectrum is dirty because your ring oscillator is free running state. But I can't figure out your situations any more with only spectrum. How to probe signal ? What instruments do you have and use ? Can you measure envelope_amplitude v.s. time ? Can you measure Frequency Deviation v.s. time ? |
Title: Re: phase noise questions? Post by liletian on May 4th, 2009, 9:05am pancho_hideboo wrote on May 4th, 2009, 8:53am:
Can you explain more free running state? In which state it will be better spectrum? how yo measure envelope_amplitude v.s. time ? Frequency Deviation v.s. time ? what's the use of it? I use agilent spectrum analysizer to measure it and GSG probe. |
Title: Re: phase noise questions? Post by pancho_hideboo on May 4th, 2009, 9:11am It seems you don't have much experiences of actual measurements. liletian wrote on May 4th, 2009, 9:05am:
liletian wrote on May 4th, 2009, 9:05am:
liletian wrote on May 4th, 2009, 9:05am:
http://www.home.agilent.com/agilent/product.jspx?nid=-536902453.0.00&cc=US&lc=eng But I think your spectrum analyzer have built-in VSA89600 Vector Signal Analysis ability. Is it right ? liletian wrote on May 4th, 2009, 9:05am:
liletian wrote on May 4th, 2009, 9:05am:
liletian wrote on May 4th, 2009, 9:05am:
It seems 50ohm is loaded directly in your observation point of circuit. Your observation point of circuit have enough ability to drive load of 50ohm ? Does it require high-impedance probing, such as Giga-Pico-Probe ? |
Title: Re: phase noise questions? Post by liletian on May 5th, 2009, 8:08pm pancho_hideboo wrote on May 4th, 2009, 9:11am:
so for unlocked state, the spectrum is very dirty? liletian wrote on May 4th, 2009, 9:05am:
I do, I read a lot books, but not as much experience yet. liletian wrote on May 4th, 2009, 9:05am:
http://www.home.agilent.com/agilent/product.jspx?nid=-536902453.0.00&cc=US&lc=eng But I think your spectrum analyzer have built-in VSA89600 Vector Signal Analysis ability. Is it right ? yes, I did not use this feather yet.:) liletian wrote on May 4th, 2009, 9:05am:
Thanks, I will read manual and try to do it. liletian wrote on May 4th, 2009, 9:05am:
liletian wrote on May 4th, 2009, 9:05am:
It seems 50ohm is loaded directly in your observation point of circuit. Your observation point of circuit have enough ability to drive load of 50ohm ? yes, definitely! Does it require high-impedance probing, such as Giga-Pico-Probe ? no, for oscillator point, we did not need it! |
Title: Re: phase noise questions? Post by pancho_hideboo on May 6th, 2009, 8:55am liletian wrote on May 5th, 2009, 8:08pm:
And floors of your spectrum are very high and dirty. I suspect PSRR(POwer Supply Rejection Ratio) of your VCO. Is PSRR of your VCO enough large ? You should consult someone who has much experience of actual RF measurements about your measurement setups and usages of instruments. liletian wrote on May 5th, 2009, 8:08pm:
??? feature ? |
Title: Re: phase noise questions? Post by liletian on May 6th, 2009, 9:08am pancho_hideboo wrote on May 6th, 2009, 8:55am:
function :( |
Title: Re: phase noise questions? Post by pancho_hideboo on May 6th, 2009, 11:04am liletian wrote on May 6th, 2009, 9:08am:
Unbelievable typo !! |
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