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

Started by Unknown May 7, 2019
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
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
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 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
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.
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.
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.
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
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.
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.