Low phase Noise oscillator design in Microwave frequency range

[santosh_11]

Hello All,

I am looking for new idea to minimize phase noise in Microwave oscillators design and there measurement, please share your idea.

Thanx

 

[BigBoss]

Phase Noise id principally dominated by Quality Factor of the Tank Circuit in MW Oscillators regarding to Linear Phase Noise approximation of Leeson.There are obviously other noise related parameters such as NF, Flicker Noise corner frequency,Voltage Swing,OP Current etc. but Q factor is essentially dominant.
An accurate and robust optimization technique has been derived and explained in Ulrich Rohde's book.Its' mathematics are pretty cumbersome but it's also important to able to understand of the mechanics of the Phase Noise.
Ulrich Rohde ( and surely Randall Rhea ) is the guru of the oscillators and you can find lot information at **broken link removed**.

 

[santosh_11]

Thanx BigBoss,

As you said mathematics are pretty cumbersome and it is cumbersome in Rohde's book to, I try to go through it but right every thing is going above my head if you know some easier way please tell (more in circuit design prospective), meanwhile i am going through Rohdes's book.

Thanx

Phase Noise id principally dominated by Quality Factor of the Tank Circuit in MW Oscillators regarding to Linear Phase Noise approximation of Leeson.There are obviously other noise related parameters such as NF, Flicker Noise corner frequency,Voltage Swing,OP Current etc. but Q factor is essentially dominant.
An accurate and robust optimization technique has been derived and explained in Ulrich Rohde's book.Its' mathematics are pretty cumbersome but it's also important to able to understand of the mechanics of the Phase Noise.
Ulrich Rohde ( and surely Randall Rhea ) is the guru of the oscillators and you can find lot information at **broken link removed**.

 

[RiffMaster]

At page 5 of the pdf below you can find many rules how to minimize phase noise:

https://www.qsl.net/va3iul/Phase noise in Oscillators.pdf

 

[santosh_11]

Thanx RiffMaster,

Could you tell me which active device is better ( low 1/f noise and low noise figure) for low phase noise oscillator design. some device name etc

 

[Terminator3]

I suggest FETs that used in LNA designs. For example, ne3514s02 or better.
Must have high gain in required frequency point, because need to make weak coupling. S21 must be enough, to go through weak coupled resonator. There are many papers suggest push-push oscillator or weak coupling for low noise. Microwave absorber above oscillator is frequently suggested, there can be some unwanted RF paths between oscillator and enclosure. Also you can protect oscillator from vibrations with some special "soft" mounting of PCB inside enclosure. Vibrations can modulate frequency that goes through dielectric resonators, diodes or even transistors. Observed by knocking CW oscillator enclosure with screwdriver or by directing very loud music to it.

 

[N1UL]

I suggest FETs that used in LNA designs. For example, ne3514s02 or better.
Must have high gain in required frequency point, because need to make weak coupling. S21 must be enough, to go through weak coupled resonator. There are many papers suggest push-push oscillator or weak coupling for low noise. Microwave absorber above oscillator is frequently suggested, there can be some unwanted RF paths between oscillator and enclosure. Also you can protect oscillator from vibrations with some special "soft" mounting of PCB inside enclosure. Vibrations can modulate frequency that goes through dielectric resonators, diodes or even transistors. Observed by knocking CW oscillator enclosure with screwdriver or by directing very loud music to it.

Usefull literature :




Techniques minimize the phase noise in crystal oscillator circuits
Poddar, A.K. ; Rohde, U.L.
Frequency Control Symposium (FCS), 2012 IEEE International
DOI: 10.1109/FCS.2012.6243701
Publication Year: 2012 , Page(s): 1 - 7
Cited by: Papers (1)
IEEE CONFERENCE PUBLICATIONS




Full text access may be available. Click article title to sign in or learn about subscription options.How Low Can They Go?: Oscillator Phase Noise Model, Theoretical, Experimental Validation, and Phase Noise Measurements
Poddar, A.K. ; Rohde, U.L. ; Apte, A.M.
Microwave Magazine, IEEE
Volume: 14 , Issue: 6
DOI: 10.1109/MMM.2013.2269859
Publication Year: 2013 , Page(s): 50 - 72
Cited by: Papers (4)
IEEE JOURNALS & MAGAZINES




Getting Its Measure: Oscillator Phase Noise Measurement Techniques and Limitations
Rohde, U.L. ; Poddar, A.K. ; Apte, A.M.
Microwave Magazine, IEEE
Volume: 14 , Issue: 6
DOI: 10.1109/MMM.2013.2269860
Publication Year: 2013 , Page(s): 73 - 86
Cited by: Papers (5)

 

[D.A.(Tony)Stewart]

The challenge in high Q microwave involves very low C in the passivation layers and low ESR in the series connections of the coil to get a high Q proportional to L/C ratio.