[time-nuts] xtal oscillator phase noise

Henk ten Pierick henk at deriesp.demon.nl
Tue Jan 1 07:24:37 EST 2008


On Dec 30, 2007, at 3:42, Bruce Griffiths wrote:

> Henk
>
> The 30dB/decade phase noise slope could be the result of the effect of
> low pass filtering a power supply or reference source that has
> significant flicker noise.

The reference used is an ADR455. I have not seen references  
significant better. Suggestions?

> Lack of local RF feedback and /or high dc gain from base to  
> collector in
> BJT buffer stages can produce significant flicker phase noise.

I have now doubled the dc voltage for the oscillating transistor for  
the reduction of junction capacitances. It had no result on phase noise.

Is low hfe better for phase noise?

Henk



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