How to improve VCO phase noise performance?

[hrkhari]

Hi Guys:

The phase noise of the designed pMOS based LC-VCO, 4-3GHz of tunability, was indicated to be -126dBc/Hz at 1MHz of offset frequency, when I integrated an open drain buffer the phase noise degraded to about -67dBc/Hz. When it is indicated on the phase noise of a VCO in many journals , it is around -112dBc/Hz, does this value correponds to the phase noise of an integrated buffer or standalone phase noise of the VCO?. How do I improve my phase noise performance of the integrated VCO and buffer?.Thanks in advance

Rgds

 

[BigBoss]

VCO Phase Noise

Why don't you use emitter follower to buffer your signal?? Or if you tech. is proper source follower ???
Generally we use either emitter follower or Cherry-Hooper limiting amplifier to buffer the VCO signals and in measurements we obtain -141dBm/Hz @ 4.6MHz..

Think that...