Increase stages of ring oscillator to decrease phase noise?

[cqmyg5]

ring oscillator phase noise

Hello all,

some paper said if increasing stages of ring oscillator will decrease phase noise, some paper said not and said it depending on the fixed power comsumption or not.

which one is the correct answer?

and the other question is the stages of ring oscillator impacts the tuning range or not?

thanks!

 

[mazelk]

decrease phase noise

Hi

According with "Phase Noise in Multi-Gigahertz CMOS Ring Oscillators" by Ali Hajimiri, Sotirios Limotyrakis and Thomas H. Lee, increasing stages of ring oscillator, decreases the phase noise. However, this decrease is not substantial, because increasing stages for a given power consumption may reduce the charge swing.

 

[amarnath]

the best way to reduce phase noise is to use a subdtrate bias ,this results in about 10 %reduction in phase noise.also phase noise is inversely propotional to the amount of power dissipated.some other methods are to minimise phase noise due to power supply variations,use a voltage regulator or use capacitors to filter out the variations in power supply.

regards
amarnath