Forums

Low Jitter 20MHz oscillator

Started by hbv March 1, 2013
Hi all,

We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single 
ended ), 20Mhz (+-few percent...) and most important a low jitter on 
this output (few ps).

Any ideas are welcomed. Habib.
On 03/01/2013 05:41 AM, hbv wrote:
> Hi all, > > We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single > ended ), 20Mhz (+-few percent...) and most important a low jitter on > this output (few ps). > > Any ideas are welcomed. Habib.
http://www.minicircuits.com/products/Oscillators.shtml No affiliation, just an old customer.
On Fri, 01 Mar 2013 14:41:08 +0100, hbv <habib.bouaziz@gmail.com> wrote:

>Hi all, > >We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single >ended ), 20Mhz (+-few percent...) and most important a low jitter on >this output (few ps). > >Any ideas are welcomed. Habib.
Jitter is a function of the time span over which you measure it. You can draw a graph of RMS jitter vs measurement interval, in other words the jitter when you use the oscillator to time out various intervals, like if you divided it down to lower frequencies. Cycle-to-cycle jitter dominates the low end of the graph. Most cheap crystal oscillators have a few picoseconds RMS jitter cycle-to-cycle and for timing intervals roughly up to a millisecond. If the osc is used to generate longer intervals, RMS jitter will start to increase roughly linearly with the interval, with the corner in the 1 ms range maybe. A cheap XO might have a few ps RMS jitter for short times, and maybe 5 or 10 ns per second. A really good SC-cut ovenized oscillator might have a few picoseconds jitter at 1 second. The Fox Xpresso oscillators have low cycle-to-cycle jitter, like 1 ps. Thermally insulating an XO with foam or something greatly improves long-interval jitter. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On 3/1/2013 7:41 AM, hbv wrote:
> Hi all, > > We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single > ended ), 20Mhz (+-few percent...) and most important a low jitter on > this output (few ps).
Any reasonably good crystal oscillator would do, provided sufficient power filtering. There is nothing special about few ps jitter at 20 MHz. Vladimir Vassilevsky DSP and Mixed Signal Designs www.abvolt.com
On Fri, 01 Mar 2013 11:04:27 -0600, Vladimir Vassilevsky
<nospam@nowhere.com> wrote:

>On 3/1/2013 7:41 AM, hbv wrote: >> Hi all, >> >> We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single >> ended ), 20Mhz (+-few percent...) and most important a low jitter on >> this output (few ps). > >Any reasonably good crystal oscillator would do, provided sufficient >power filtering. There is nothing special about few ps jitter at 20 MHz. > >Vladimir Vassilevsky >DSP and Mixed Signal Designs >www.abvolt.com >
You can easily slap one together with a 74HCU04. Just make sure it's the "U" version. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Fri, 01 Mar 2013 14:41:08 +0100, hbv <habib.bouaziz@gmail.com>
wrote:

>Hi all, > >We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single >ended ), 20Mhz (+-few percent...) and most important a low jitter on >this output (few ps). > >Any ideas are welcomed. Habib.
Conner-Winfield DV75C series has maximum integrated phase jitter 1ps RMS over 12kHz to 20MHz. Period jitter 5ps RMS maximum. Also very good temperature stability for a low-power non-ovenized oscillator (which I happen to need). Some info on jitter specs:- http://www.silabs.com/Support%20Documents/TechnicalDocs/AN256.pdf
On 2013-03-01 18:07, Jim Thompson wrote:
> On Fri, 01 Mar 2013 11:04:27 -0600, Vladimir Vassilevsky > <nospam@nowhere.com> wrote: > >> On 3/1/2013 7:41 AM, hbv wrote: >>> Hi all, >>> >>> We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single >>> ended ), 20Mhz (+-few percent...) and most important a low jitter on >>> this output (few ps). >> >> Any reasonably good crystal oscillator would do, provided sufficient >> power filtering. There is nothing special about few ps jitter at 20 MHz. >> >> Vladimir Vassilevsky >> DSP and Mixed Signal Designs >> www.abvolt.com >> > > You can easily slap one together with a 74HCU04. Just make sure it's > the "U" version. >
Making an oscillator is easy. Making a low jitter oscillator isn't. A few uV of power supply noise would mess up the jitter specs of a 74HCU04 based oscillator. Minuscule temperature variations would probably do the same. Jeroen Belleman
On Fri, 01 Mar 2013 21:38:07 +0100, Jeroen <jeroen@nospam.please>
wrote:

>On 2013-03-01 18:07, Jim Thompson wrote: >> On Fri, 01 Mar 2013 11:04:27 -0600, Vladimir Vassilevsky >> <nospam@nowhere.com> wrote: >> >>> On 3/1/2013 7:41 AM, hbv wrote: >>>> Hi all, >>>> >>>> We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single >>>> ended ), 20Mhz (+-few percent...) and most important a low jitter on >>>> this output (few ps). >>> >>> Any reasonably good crystal oscillator would do, provided sufficient >>> power filtering. There is nothing special about few ps jitter at 20 MHz. >>> >>> Vladimir Vassilevsky >>> DSP and Mixed Signal Designs >>> www.abvolt.com >>> >> >> You can easily slap one together with a 74HCU04. Just make sure it's >> the "U" version. >> > >Making an oscillator is easy. Making a low jitter oscillator isn't. >A few uV of power supply noise would mess up the jitter specs of >a 74HCU04 based oscillator. Minuscule temperature variations would >probably do the same. > >Jeroen Belleman
I doubt the "Minuscule temperature variations", and bypass capacitors are there for a reason >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
hbv wrote:

> Hi all, > > We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single > ended ), 20Mhz (+-few percent...) and most important a low jitter on > this output (few ps). > > Any ideas are welcomed. Habib.
Xtal base clock for 20 mhz should be ok.. Digikey has lots of XC type osc that are surface mount that fits your needs. Jamie
On Fri, 01 Mar 2013 14:41:08 +0100, hbv <habib.bouaziz@gmail.com>
wrote:

>Hi all, > >We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single >ended ), 20Mhz (+-few percent...) and most important a low jitter on >this output (few ps). > >Any ideas are welcomed. Habib.
How do you plan to measure the jitter? Why does it matter? -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation