looking for SMT oscillator SC cut, with no oven
For a project at work, I'm looking for a good close in phase noise
oscillator (better than -100dBc@ 10Hz, -120dBc would be nice) at 100 MHz
in a SMT form factor. But it doesn't need good temperature stability.
There's tons of SMT OCXOs out there with reasonably good performance,
but they draw "watts". My application is actually quite temperature
stable already AND I have an external reference to measure against.
Most of the lower powered oscillator modules are TCXO, and have, maybe,
-80dBc at 10MHz.
I guess we could go to a discrete design with a crystal and amplifier,
but a little clock module would be a simpler solution.
Hello, Jim,
I suppose that one of the alternatives that you've explored are the
ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf
They say that they are 3rd overtone, but it seems more an AT-cut than a
SC, and anyway is around 10dB poorer than your requirements. An I
suppose that to make surgery in an AOCJY (that fully meets your
requirement) to remove the oven will not be adequate :) Also it is a bit
bulky...
Regards,
Javier
On 26/08/2015 20:23, Jim Lux wrote:
For a project at work, I'm looking for a good close in phase noise
oscillator (better than -100dBc@ 10Hz, -120dBc would be nice) at 100
MHz in a SMT form factor. But it doesn't need good temperature
stability. There's tons of SMT OCXOs out there with reasonably good
performance, but they draw "watts". My application is actually quite
temperature stable already AND I have an external reference to measure
against.
Most of the lower powered oscillator modules are TCXO, and have,
maybe, -80dBc at 10MHz.
I guess we could go to a discrete design with a crystal and amplifier,
but a little clock module would be a simpler solution.
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Rakon has always impressed me .
From: Jim Lux jimlux@earthlink.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Wednesday, August 26, 2015 11:23 AM
Subject: [time-nuts] looking for SMT oscillator SC cut, with no oven
For a project at work, I'm looking for a good close in phase noise
oscillator (better than -100dBc@ 10Hz, -120dBc would be nice) at 100 MHz
in a SMT form factor. But it doesn't need good temperature stability.
There's tons of SMT OCXOs out there with reasonably good performance,
but they draw "watts". My application is actually quite temperature
stable already AND I have an external reference to measure against.
Most of the lower powered oscillator modules are TCXO, and have, maybe,
-80dBc at 10MHz.
I guess we could go to a discrete design with a crystal and amplifier,
but a little clock module would be a simpler solution.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Am 26.08.2015 um 22:04 schrieb Javier Herrero:
I suppose that one of the alternatives that you've explored are the
ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf
looks just like this one from Crystek:
< http://www.digikey.de/product-search/de?keywords=cvhd-950 >
but that fails the specs, also. If you have a good quality 5 or 10 MHz
source in your
system, you can lock the VCXO to it and clean it up close to the carrier.
Last week, I asked for the prices of the 100 MHz Pascalls (not SMD but SMA)
but at > € 4K +VAT a piece I better make someone select crystals myself. :-(
Maybe Axtal has something.
They say that they are 3rd overtone, but it seems more an AT-cut than
a SC, and anyway is around 10dB poorer
SC requires high temperature, that does not go together well with SMD
and low power.
regards, Gerhard
On 8/26/15 1:04 PM, Javier Herrero wrote:
Hello, Jim,
I suppose that one of the alternatives that you've explored are the
ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf
They say that they are 3rd overtone, but it seems more an AT-cut than a
SC, and anyway is around 10dB poorer than your requirements. An I
suppose that to make surgery in an AOCJY (that fully meets your
requirement) to remove the oven will not be adequate :) Also it is a bit
bulky...
exactly.. I've thought about delidding a OCXO and cutting the trace.
That's a fairly expensive operation, maybe? (by the time we find a tech
to do it, write the procedure, etc.) It would turn a $50 oscillator
into a several thousand dollar oscillator. Still cheaper than designing
a new oscillator from scratch.
Or if someone knows of an OCXO where the oven power is separate from the
oscillator power, that would make it easy.
Darn these highly integrated parts..<grin>
On 8/26/15 1:28 PM, steve heidmann via time-nuts wrote:
Rakon has always impressed me .
I'll take a look. The online datasheets don't have phase noise data for
close in frequencies (at least the 3 I looked at).. some give a
"integrated jitter" but it's for 12kHz and out, and I've noticed there's
lots of "ultra low noise, low jitter" oscillators out there that have
very good noise performance from a few kHz out, but are pretty bad at 10
and 100 Hz.
But if he needs 100dBc at 10Hz that is Wenzel's stronghold
[https://twitter.com/ultralownoise]
look that: http://www.wenzel.com/wp-content/parts/501-04517.pdf
73
KJ6UHN
Alex
On 8/26/2015 2:38 PM, Gerhard Hoffmann wrote:
Am 26.08.2015 um 22:04 schrieb Javier Herrero:
I suppose that one of the alternatives that you've explored are the
ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf
looks just like this one from Crystek:
< http://www.digikey.de/product-search/de?keywords=cvhd-950 >
but that fails the specs, also. If you have a good quality 5 or 10 MHz
source in your
system, you can lock the VCXO to it and clean it up close to the carrier.
Last week, I asked for the prices of the 100 MHz Pascalls (not SMD but
SMA)
but at > € 4K +VAT a piece I better make someone select crystals
myself. :-(
Maybe Axtal has something.
They say that they are 3rd overtone, but it seems more an AT-cut than
a SC, and anyway is around 10dB poorer
SC requires high temperature, that does not go together well with SMD
and low power.
regards, Gerhard
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On 8/26/15 2:38 PM, Gerhard Hoffmann wrote:
Am 26.08.2015 um 22:04 schrieb Javier Herrero:
I suppose that one of the alternatives that you've explored are the
ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf
looks just like this one from Crystek:
< http://www.digikey.de/product-search/de?keywords=cvhd-950 >
Yep, that's one (and similar ones) that's my current "best I found in an
hour of googling"
but that fails the specs, also. If you have a good quality 5 or 10 MHz
source in your
system, you can lock the VCXO to it and clean it up close to the carrier.
Nope.. this oscillator is the ADC clock: it's a direct sampling receiver
to look at narrow band signals in the 3-30 MHz range.
Maybe Axtal has something.
I'll look..
They say that they are 3rd overtone, but it seems more an AT-cut than
a SC, and anyway is around 10dB poorer
SC requires high temperature, that does not go together well with SMD
and low power.
SC only requires high temperature if you want to operate close to the
turnover to minimize temperature effects.
I've got a GPS 1pps to count my oscillator, so the sampled data can be
post processed to take out the frequency variations. You'd get a bunch
of digital samples and the timestamps when the 1pps occurs.
I'm kind of hoping someone has run across a SMT OCXO where there's a
separate oscillator and oven power pin.
On 8/26/15 4:46 PM, Alex Pummer wrote:
But if he needs 100dBc at 10Hz that is Wenzel's stronghold
[https://twitter.com/ultralownoise]
look that: http://www.wenzel.com/wp-content/parts/501-04517.pdf
Yep.. got one of those sitting on my desk (or one that's very similar)..
but it's a 2x2" block that draws many watts..
I want something that is 0.5x0.5" and draws 100-200 milliwatts or so.
You might start with Leeson's equation to calculate the resonator Q that you
need to get the phase noise you desire. Overtone resonators have higher Q,
but they are too "stiff" to keep on frequency (with a reactive tuning
network) under conditions in which the resonator is exposed to any practical
range of (ambient) temperatures. Said another way, to get the phase noise
you desire, you may need a Q that can only be achieved with an overtone
resonator that cannot be brought/kept on frequency except by keeping its
temperature stable (which needs to be above any expected ambient).
There is a lot of good material on this topic at
http://www.ieee-uffc.org/publications/books/index.asp
If you can afford the complexity and power of synthesizing the desired
frequency (with a DDS, perhaps) from the overtone resonator you could absorb
the resonator inaccuracy with tuning commands that you send to the DDS.
Mike
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Jim Lux
Sent: Wednesday, August 26, 2015 2:24 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] looking for SMT oscillator SC cut, with no oven
For a project at work, I'm looking for a good close in phase noise
oscillator (better than -100dBc@ 10Hz, -120dBc would be nice) at 100 MHz in
a SMT form factor. But it doesn't need good temperature stability.
There's tons of SMT OCXOs out there with reasonably good performance, but
they draw "watts". My application is actually quite temperature stable
already AND I have an external reference to measure against.
Most of the lower powered oscillator modules are TCXO, and have, maybe,
-80dBc at 10MHz.
I guess we could go to a discrete design with a crystal and amplifier, but a
little clock module would be a simpler solution.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.