1ns max jitter oscillator, cheap - for fast 4 diode sampler

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

So I need a pretty good oscillator, with low jitter

I have never needed a good oscillator before, so on this topic I am totally at square one

First I was thinking about an RC oscillator, and cleaning up the jitter. RC typically have 1us of jitter (found info on the web), and a crystal oscillator, standard type probably 1ns jitter. But I think that idea was crazy, a PLL clean up, would not work I guess.

In order to not mess up my measurement and keep the averaging low (I could do many samples and average), I would guess I need jitter of 300ps (10%) of my 3ns reolution)

But jitter is not listed as a search parameter. So where to start? (with low price in mind)

Cheers

Klaus

 

[John Larkin]

On Tue, 7 May 2019 07:14:33 -0700 (PDT), klaus.kragelund@gmail.com
wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

So I need a pretty good oscillator, with low jitter

I have never needed a good oscillator before, so on this topic I am totally at square one

First I was thinking about an RC oscillator, and cleaning up the jitter. RC typically have 1us of jitter (found info on the web), and a crystal oscillator, standard type probably 1ns jitter. But I think that idea was crazy, a PLL clean up, would not work I guess.

In order to not mess up my measurement and keep the averaging low (I could do many samples and average), I would guess I need jitter of 300ps (10%) of my 3ns reolution)

But jitter is not listed as a search parameter. So where to start? (with low price in mind)

Cheers

Klaus

Do you want a continuous running oscillator, namely a crystal
oscillator? That works if the measured event and the sampler timebase
can run off the same clock. Even cheap XOs have picosecond or
sub-picosecond jitter measured over short time spans. Longer spans are
trashed by low frequency phase noise, numbers in the nanoseconds per
second for cheap XOs, picoseconds per second for good OCXOs.

Most XOs now have a jitter spec on their data sheet. Some spec
femtosecond period jitter.

Sampling oscilloscopes typically need async triggered timebase
oscillators, which are more difficult. Jitters like 1 part in 50,000
(jitter 20 PPM RMS times timed delay) are more common for a triggered
LC, like on an 11801. 1 part per million is possible; I'm doing that
now.

A triggered oscillator can be phase locked to a good XO while
preserving the trigger alignment.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Phil Hobbs]

On 5/7/19 10:14 AM, klaus.kragelund@gmail.com wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

So I need a pretty good oscillator, with low jitter

I have never needed a good oscillator before, so on this topic I am totally at square one

First I was thinking about an RC oscillator, and cleaning up the jitter. RC typically have 1us of jitter (found info on the web), and a crystal oscillator, standard type probably 1ns jitter. But I think that idea was crazy, a PLL clean up, would not work I guess.

In order to not mess up my measurement and keep the averaging low (I could do many samples and average), I would guess I need jitter of 300ps (10%) of my 3ns reolution)

But jitter is not listed as a search parameter. So where to start? (with low price in mind)

Cheers

Klaus

A standard XO is nowhere near as bad as 1 ns. That would be half a
radian worth at 100 MHz.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

On Wednesday, May 8, 2019 at 12:14:39 AM UTC+10, klaus.k...@gmail.com wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

So I need a pretty good oscillator, with low jitter

I have never needed a good oscillator before, so on this topic I am totally at square one

First I was thinking about an RC oscillator, and cleaning up the jitter. RC typically have 1us of jitter (found info on the web), and a crystal oscillator, standard type probably 1ns jitter. But I think that idea was crazy, a PLL clean up, would not work I guess.

In order to not mess up my measurement and keep the averaging low (I could do many samples and average), I would guess I need jitter of 300ps (10%) of my 3ns reolution)

But jitter is not listed as a search parameter. So where to start? (with low price in mind)

This isn't a low price solution, but etched crystals were commercially available to up to about 600MHz, and the jitter on their output was less than a picosecond.

Some twenty years ago I was planning on buying in a crystal oscillator that ran at 500MHz with ECL outputs, for about 100 euro.

Today's parts are more widely available and appear to go up to 2.1GHz

https://uk.farnell.com/abracon/ax5pbf1-500-0000c/oscillator-500mhz-lvpecl-5mm-x/dp/2986239

http://www.farnell.com/datasheets/2713167.pdf

They seem to have gotten cheaper too.

Still not cheap.

--
Bill Sloman, Sydney

 

[Gerhard Hoffmann]

Am 07.05.19 um 19:20 schrieb Cursitor Doom:

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.


ROTFL.

A Q like a wet sand bag.

 

[Cursitor Doom]

On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.




--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

 

[Winfield Hill]

Tom Gardner wrote...

On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

Yes, I would have gone for a crystal, or at least a
high-Q LC oscillator.


--
Thanks,
- Win

 

[bitrex]

On 5/7/19 1:20 PM, Cursitor Doom wrote:

On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

In a rare moment of partial agreement with my arch-nemesis "Cursitor
Doom" an injecton-locked Wien bridge oscillator can provide a
near-perfect combination of very low phase noise and very low wideband
noise floor and distortion. And certainly meets the low-price requirement.

 

[bitrex]

On 5/7/19 3:08 PM, Tom Gardner wrote:

On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

He's right about the spectral purity and the phase noise can be cleaned
up by injection-locking it.

 

[Tom Gardner]

On 07/05/19 18:20, Cursitor Doom wrote:

On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

 

On Tuesday, 7 May 2019 17:18:48 UTC+2, John Larkin wrote:

On Tue, 7 May 2019 07:14:33 -0700 (PDT), klaus.kragelund@gmail.com
wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

So I need a pretty good oscillator, with low jitter

I have never needed a good oscillator before, so on this topic I am totally at square one

First I was thinking about an RC oscillator, and cleaning up the jitter. RC typically have 1us of jitter (found info on the web), and a crystal oscillator, standard type probably 1ns jitter. But I think that idea was crazy, a PLL clean up, would not work I guess.

In order to not mess up my measurement and keep the averaging low (I could do many samples and average), I would guess I need jitter of 300ps (10%) of my 3ns reolution)

But jitter is not listed as a search parameter. So where to start? (with low price in mind)

Cheers

Klaus

Do you want a continuous running oscillator, namely a crystal
oscillator? That works if the measured event and the sampler timebase
can run off the same clock. Even cheap XOs have picosecond or
sub-picosecond jitter measured over short time spans. Longer spans are
trashed by low frequency phase noise, numbers in the nanoseconds per
second for cheap XOs, picoseconds per second for good OCXOs.

That is a very good point, great catch.

I will be using it in a TDR, so short pulse, and build up waveform for reflected pulse. Since I need up to 200m lenth, the maximum time from the emitted pulse to reflected is 3us. So if the jitter is slowly changing over time, it may be a lot less in only that time span.

I do not know the properties of crystal jitter. Would that be sinusoidal shaped?

Most XOs now have a jitter spec on their data sheet. Some spec
femtosecond period jitter.

I looked at Digikey. The cheapest XO (about 0.5 USD) has 3ps jitter:

https://www.sitime.com/datasheet/SiT8008

A lot better than what I need.

When looking at oscillators, the cheapest (0.4 USD) also has only 3ps:

https://www.sitime.com/datasheet/SiT2001

For crystals, I see no spec of jitter:

https://abracon.com/Resonators/abls.pdf

But, I guess that is because that makes no sense if the inverter used for the crystal is defined. For microcontrollers I never see a spec for the jitter, maybe it is horrendous

I have seen jitter defined for the PLL. For example for a ST controller:

https://www.st.com/resource/en/datasheet/stm32g071cb.pdf

Page 76, defines 40ps jitter. Cannot see if that is from RC or crystal clock. But is most likely crystal clock. So it seems, I can use a cheap crystal for the microontroller and get a sufficient low jitter figure

Sampling oscilloscopes typically need async triggered timebase
oscillators, which are more difficult. Jitters like 1 part in 50,000
(jitter 20 PPM RMS times timed delay) are more common for a triggered
LC, like on an 11801. 1 part per million is possible; I'm doing that
now.

A triggered oscillator can be phase locked to a good XO while
preserving the trigger alignment.


Thanks for the very good info

Regards

Klaus

 

[Jeroen Belleman]

On 2019-05-07 21:37, bitrex wrote:

On 5/7/19 1:20 PM, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.





In a rare moment of partial agreement with my arch-nemesis "Cursitor
Doom" an injecton-locked Wien bridge oscillator can provide a
near-perfect combination of very low phase noise and very low wideband
noise floor and distortion. And certainly meets the low-price requirement.

While Wien bridge oscillators may have low distortion and therefore
good spectral purity, they certainly aren't low noise. I mean, even
the frequency-selective part is lossy, dissipative and therefore
noisy.

Jitter is the uncertainty in the timing of some level crossing.
This uncertainty depends on the noise level and on the rate of
change of the signal around that level crossing. To get low jitter,
you want the noise to be as low as possible and you want to cross
the decision level as fast as possible.

So you want a low-loss resonator, a low noise feedback amplifier,
high oscillation amplitude and high frequency. That pretty much
rules out a Wien bridge oscillator, or any RC oscillator for
that matter.

For timing a fast sampler, jitter performance doesn't need to
be stellar. It shouldn't be too hard to get jitter in the few
tens of picoseconds ballpark, even with an RC oscillator.

Jeroen Belleman

 

[George Herold]

On Tuesday, May 7, 2019 at 4:08:37 PM UTC-4, George Herold wrote:

On Tuesday, May 7, 2019 at 4:01:58 PM UTC-4, George Herold wrote:
On Tuesday, May 7, 2019 at 3:47:01 PM UTC-4, klaus.k...@gmail.com wrote:
On Tuesday, 7 May 2019 21:39:08 UTC+2, bitrex wrote:
On 5/7/19 3:08 PM, Tom Gardner wrote:
On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

He's right about the spectral purity and the phase noise can be cleaned
up by injection-locking it.

How do you clean up the oscillator by injection? Got an example?

Yeah me too. Curious minds want to know.
In my very limited experience, the spectral purity depended on
how 'strong' the AGC was.

George H.

Cheers

Klaus

This maybe.
https://www.analog.com/en/technical-articles/injection-lock-a-wien-bridge-oscillator.html

GH

OK last thing. I stuck my Wien bridge on the good SRS 720 spectrum analyzer and the 3rd was ~90 db down. (my above 70 dB number was measuring on a 'scope, not so good.)

GH
FFT.)

 

[George Herold]

On Tuesday, May 7, 2019 at 4:01:58 PM UTC-4, George Herold wrote:

On Tuesday, May 7, 2019 at 3:47:01 PM UTC-4, klaus.k...@gmail.com wrote:
On Tuesday, 7 May 2019 21:39:08 UTC+2, bitrex wrote:
On 5/7/19 3:08 PM, Tom Gardner wrote:
On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

He's right about the spectral purity and the phase noise can be cleaned
up by injection-locking it.

How do you clean up the oscillator by injection? Got an example?

Yeah me too. Curious minds want to know.
In my very limited experience, the spectral purity depended on
how 'strong' the AGC was.

George H.

Cheers

Klaus

This maybe.
https://www.analog.com/en/technical-articles/injection-lock-a-wien-bridge-oscillator.html

GH

 

[George Herold]

On Tuesday, May 7, 2019 at 3:47:01 PM UTC-4, klaus.k...@gmail.com wrote:

On Tuesday, 7 May 2019 21:39:08 UTC+2, bitrex wrote:
On 5/7/19 3:08 PM, Tom Gardner wrote:
On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

He's right about the spectral purity and the phase noise can be cleaned
up by injection-locking it.

How do you clean up the oscillator by injection? Got an example?

Yeah me too. Curious minds want to know.
In my very limited experience, the spectral purity depended on
how 'strong' the AGC was.

George H.

Cheers

Klaus

 

[George Herold]

On Tuesday, May 7, 2019 at 3:08:42 PM UTC-4, Tom Gardner wrote:

On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

Hmm, Well I know little of phase noise, but if it's at all related to
harmonic distortion... Then I will say I've built a little Wien bridge
oscillator (audio) with light bulb AGC (ala Jim Williams, ala Bill Hewlett)
And it's slick. The 2nd harmonic is hard to see without fancy kit and
the 3rd harmonic is ~70 dB down. Which is better than my Rigol DDS
Sig Gen. (about -70 dB 2nd and -60 on 3rd)

I'm not sure my objection has anything to do with ns phase noise.

George H.

 

On Tuesday, 7 May 2019 21:39:08 UTC+2, bitrex wrote:

On 5/7/19 3:08 PM, Tom Gardner wrote:
On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

He's right about the spectral purity and the phase noise can be cleaned
up by injection-locking it.

How do you clean up the oscillator by injection? Got an example?

Cheers

Klaus

 

On Tuesday, 7 May 2019 19:20:49 UTC+2, Cursitor Doom wrote:

On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

So I could use a Wien Bridge oscillator, or a cheap colpits?

Then use the cheap crystal osc in the microcontroller to compensate the measurements (measure the colpits frequency and correct the numbers)

Cheers

Klaus

 

On Tuesday, 7 May 2019 22:27:27 UTC+2, George Herold wrote:

On Tuesday, May 7, 2019 at 4:08:37 PM UTC-4, George Herold wrote:
On Tuesday, May 7, 2019 at 4:01:58 PM UTC-4, George Herold wrote:
On Tuesday, May 7, 2019 at 3:47:01 PM UTC-4, klaus.k...@gmail.com wrote:
On Tuesday, 7 May 2019 21:39:08 UTC+2, bitrex wrote:
On 5/7/19 3:08 PM, Tom Gardner wrote:
On 07/05/19 18:20, Cursitor Doom wrote:
On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

Hi

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

No, but that statement is about as sensible as almost
all your statements.

He's right about the spectral purity and the phase noise can be cleaned
up by injection-locking it.

How do you clean up the oscillator by injection? Got an example?

Yeah me too. Curious minds want to know.
In my very limited experience, the spectral purity depended on
how 'strong' the AGC was.

George H.

Cheers

Klaus

This maybe.
https://www.analog.com/en/technical-articles/injection-lock-a-wien-bridge-oscillator.html

GH

OK last thing. I stuck my Wien bridge on the good SRS 720 spectrum analyzer and the 3rd was ~90 db down. (my above 70 dB number was measuring on a 'scope, not so good.)

That's the next thing. I need to find a scope that is good enough to measure the jitter. One of my work colleagues has one.

At home I have a TDS744A, which has 80ps jitter. So I can use that for rough measurements

 

[whit3rd]

On Tuesday, May 7, 2019 at 10:20:49 AM UTC-7, Cursitor Doom wrote:

On Tue, 07 May 2019 07:14:33 -0700, klaus.kragelund wrote:

I'm working on my ~3ns 4 diode sampler (preferable 1ns if possible)
[and want a low-jitter oscillator]

I know I'll appear a dinosaur by saying this, but you really can't beat a
good old fashioned Wien Bridge oscillator when it comes to spectral
purity and low phase noise. They certainly beat the crap out of any
digital synthesis technique IMV.

The best timing performance requires significant stored energy,
if only for Heisenberg uncertainty principles. That means LC beats RC
circuitry (the resistors don't store energy, they just waste it). A rock
has the full momentum of the standing wave acoustics, so a crystal is better
than LC. Short of maser/resonant cavity references, the possibilities are good
for plain old wires as delay lines (distributed L, C) also.

World-class timing uses superconducting cavities, if that matters.