On Jan 2, 2008, at 0:06, Bruce Griffiths wrote:
Henk
The circuit diagram helps a lot.
Thanks a lot for the comments on the schematic, they explain a lot.
I will create some circuit schematics for crystal oscillators that
control the crystal current more directly and use a common base
Henk
Henk ten Pierick wrote:
Meanwhile look at:
http://www.ko4bb.com/~bruce/LPND.html
http://www.ko4bb.com/%7Ebruce/LPND.html
I did and it was very helpful
This crystal oscillator circuit is a variant of the low noise
oscillator
proposed by Wenzel for use with fundamental
Henk ten Pierick wrote:
--snip--
It showed to be very difficult to come lower than what I have now. If
can be the crystal. How can I decide?
As an absolute minimum, you need to know the crystal dynamic (or
motional) parameters - the crystal supplier should be able to provide
these. If
Not really, it's the circuit topology determines whether a parallel or
series resonant crystal is used. Your circuit appears to be a variant
Just a comment about series vs parallel. The 10811 has a parallel
resonant circuit and the E1938A has a series resonant circuit.
The crystals used
I think the main difference between parallel and series resonance is that in
parallel resonance mode, the capacitance of the crystal holder and wiring to
the crystal is part of the frequency determining parameters, and in series mode
it is not. So it may have a slight effect on temperature
I forgot to mention that the crystals for the E1938A had to
be calibrated for series resonance at 10 MHz.
Rick Karlquist N6RK
Didier Juges wrote:
I think the main difference between parallel and series resonance is that in
parallel resonance mode, the capacitance of the crystal holder and
Grant Hodgson wrote:
Henk ten Pierick wrote:
--snip--
It showed to be very difficult to come lower than what I have now. If
can be the crystal. How can I decide?
As an absolute minimum, you need to know the crystal dynamic (or
motional) parameters - the crystal supplier should
On Dec 30, 2007, at 19:03, Grant Hodgson wrote:
Henk
Two things will dominate if you want such a low phase noise spec.:-
the
loaded Q of the oscillator circuit, and the flicker corner frequency
of the sustaining amplifier transistor. To get a high loaded Q you
need
a crystal with
:[EMAIL PROTECTED] 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:
Henk
The 30dB/decade phase noise slope could
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:
Henk
The 30dB/decade phase noise slope could be the result of the
effect of
low pass filtering a power supply
PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Henk ten Pierick
Sent: Tuesday, January 01, 2008 8:03 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] xtal oscillator phase noise
On Jan 1, 2008, at 13:42, Mike Feher wrote:
Henk -
Did you try to measure the PN
] [mailto:time-nuts-
[EMAIL PROTECTED] On
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Sent: Tuesday, January 01, 2008 8:03 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] xtal oscillator phase noise
On Jan 1, 2008, at 13:42, Mike Feher wrote:
Henk -
Did you try to measure
:[EMAIL PROTECTED] On
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Sent: Tuesday, January 01, 2008 9:20 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] xtal oscillator phase noise
On Jan 1, 2008, at 14:13, Mike Feher wrote:
The emitter follower should have a very low output
For what it's worth, the Wenzel 5 and 10 MHz ULN oscillators are
generally considered to be about the lowest noise oscillators
commercially available. They really shine in their noise floor.
There's actually (at least) one 5MHz oscillator with a better 1Hz offset
spec -- the Oscilloquartz
732-886-5960
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Tom Van Baak
Sent: Tuesday, January 01, 2008 2:02 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] xtal oscillator phase noise
For what it's worth
Tom -
Nice data. It really confirms what I initially posted. Your measurements
were at 5 MHz, so, the expected number at 10 MHz would be 6 dB worse. The
-155 dBc/Hz number quoted by memory from me then was not that far of at all.
- Mike
Hi Mike,
What's the math behind why an equivalently
PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Mike Feher
Sent: Tuesday, January 01, 2008 2:12 PM
To: 'Tom Van Baak'; 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] xtal oscillator phase noise
Tom -
Nice data. It really confirms what I initially posted. Your
Sent: Tuesday, January 01, 2008 2:22 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] xtal oscillator phase noise
Tom -
Nice data. It really confirms what I initially posted. Your measurements
were at 5 MHz, so, the expected number at 10 MHz would be 6 dB
measurement'
Subject: Re: [time-nuts] xtal oscillator phase noise
Tom -
Nice data. It really confirms what I initially posted. Your measurements
were at 5 MHz, so, the expected number at 10 MHz would be 6 dB
worse. The
-155 dBc/Hz number quoted by memory from me then was not that
far
In the HP 10816 Rb frequency standard, we used a modified
10811 oscillator circuit. The oscillator and first buffer
amplifier transistor were the same, but the rest of the
buffer amplifier was replaced with a cascaded grounded
base buffer amplifier. We were able to get numbers comparable
to
Henk ten Pierick wrote:
Bruce,
1. Best wishes.
2. It has taken some time but here is the schematic.
Henk
Henk
The circuit diagram helps a lot.
1) Since the crystal current is 1mA the RF voltage across R2 (and the RF
at the input of the HC04) is 220mV rms (622mV pp).
This is a little low
Bruce, do you get out much?Don.
- Original Message -
From: Bruce Griffiths [EMAIL PROTECTED]
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Sunday, December 30, 2007 3:42 PM
Subject: Re: [time-nuts] xtal oscillator phase noise
Henk
Don Collie wrote:
Bruce, do you get out much?Don.
- Original Message -
Don
I do give at least one public talk a month.
Also have done such things as attempting to measure the wavefont
distortion of a telescope using very little equipment.
The oft sited eyeball star
Henk
Two things will dominate if you want such a low phase noise spec.:- the
loaded Q of the oscillator circuit, and the flicker corner frequency
of the sustaining amplifier transistor. To get a high loaded Q you need
a crystal with a high unloaded Q - maybe 100 000 or more - this isn't
AFAIK, in a crystal oscillator specifically (not oscillators
in general), the oscillator transistor has almost nothing to
do with either close in or far out phase noise. The close in
phase noise is typically limited by the crystal's intrinsic
noise and the far out phase noise is limited by the
Grant Hodgson wrote:
Henk
Two things will dominate if you want such a low phase noise spec.:- the
loaded Q of the oscillator circuit, and the flicker corner frequency
of the sustaining amplifier transistor. To get a high loaded Q you need
a crystal with a high unloaded Q - maybe 100
Henk ten Pierick wrote:
Hello,
Some questions on xtal oscillator phase noise. Attached the
measurement result of my series resonant xtal oscillator.
It is a class A, ibias 5 mA, Ixtal 1 mArms. Transistor selected for
low Rbb' 20 Ohm, Ft 100MHz. Reference voltage 5V from an ADR445,
filtered
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.
Lack of local RF feedback and /or high dc gain from base to collector in
BJT buffer stages can produce significant flicker phase
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