[time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

Attila Kinali attila at kinali.ch
Sun Nov 8 17:19:59 EST 2015


Thanks everyone for answering my questions and englighting me on
the general topic.

Sorry for the late answer from my side. It took me some time to
read up on all the pointers and hints provided. I'll quickly add
some  comments and questions to a few of the mails, that I find
noteworth, while i'm digging deeper into the topic.

On Tue, 27 Oct 2015 01:31:36 +0000 (UTC)
Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:

> http://ri.search.yahoo.com/_ylt=AwrTcaxMzS5WgJIAMwk3QIpQ;_ylu=X3oDMTBzbW1zYXBzBHNlYwNzcgRwb3MDMjEEY29sbwNncTEEdnRpZAM-/RV=2/RE=1445936589/RO=10/RU=https%3a%2f%2fescies.org%2fdownload%2fwebDocumentFile%3fid%3d60902/RK=0/RS=.Rmksavr9Ui3TZ8D1XyZ06TpeDY-

The correct URL here is https://escies.org/download/webDocumentFile?id=60902
and referencing to the document
"Low Noise Master Oscillator LNMO" by Wagner and Desaules.

On Mon, 26 Oct 2015 20:19:35 -0700
"Richard (Rick) Karlquist" <richard at karlquist.com> wrote:

> The oscillator transistor and buffer amplifier are basically
> the same as the HP 10811, except for the absence of mode
> suppressors.  The difference here is that the oscillator
> self limits in the oscillator transistor, whereas the 10811
> has ALC.  The discontinuous operation of the transistor,
> as explained by Driscoll some 45 years ago, is undesirable
> because it increases the load resistance the crystal sees.

Driscoll wrote a lot about oscillators over the years.
I couldn't find anything specific to discontinuous operation.
Do you have a titel of a paper related to this?

> The 2 transistor "Driscoll oscillator" fixes this problem
> by using an additional stage that limits instead of the
> oscillator transistor.

A good introduction to Driscolls oscillator design can be found in:

"Notes on the Driscoll VHF Overtone Crystal Oscillator and
New Low-Noise VHF Crystal Oscillator Topology" by Chris Bartram GW4DGU, 2008
page 5 in "Scatterpoint"

> I have demonstrated that the close in phase noise in
> the 10811 is entirely due to the flicker noise of the
> crystal.  The only place where the 10811 circuit comes
> into play is beyond 1 kHz from the carrier, where the
> Burgoon patent circuit (which apparently has prior art

Is the Burgoon patent you are refering to US4283691
"Crystal oscillator having low noise signal extraction circuit" ?

On Wed, 28 Oct 2015 06:45:54 -0700
"Richard (Rick) Karlquist" <richard at karlquist.com> wrote:

> Bruce has it exactly right.  At offset frequencies beyond 1 kHz,
> the source impedance for the grounded base is very high due to
> the crystal impedance being very high.  As Burgoon explains,
> this condition suppresses base recombination noise, and the
> only noise mechanism that is significant is the collector shot
> noise.  (To minimize shot noise, don't run more DC collector
> current than necessary).
> I read Ulrich Rohde's 1977 article showing this circuit,
> before I started working at HP in 1979.  When I got to HP,

The article in question is either 

"Stable Crystal Oscillators", Ham Radio Magazine, June, 1975
"Effects of Noise in Receiving System", Ham Radio Magazine, November 1977

Unfortunately, there doesn't seem to be an online source for the
Ham Radio Magazine. If anyone has a digital version of these
articles, I would appreciate a copy.

			Attila Kinali

Reading can seriously damage your ignorance.
		-- unknown

More information about the time-nuts mailing list