[time-nuts] xtal oscillator phase noise
mfeher at eozinc.com
Tue Jan 1 07:42:11 EST 2008
Did you try to measure the PN out of the oscillator directly without the
buffer amp (U1)? Also, what is the voltage from V1? Is it also 12V? HNY -
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Henk ten Pierick
Sent: Tuesday, January 01, 2008 7:25 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] xtal oscillator phase noise
On Dec 30, 2007, at 3:42, Bruce Griffiths wrote:
> 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?
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