[time-nuts] Oven Controlled Voltage Controlled SAW Oscillators

[Bob kb8tq]

Hi

Ovenized (and non-ovenized) SAW oscillators have been around as products for a long time
( a couple of decades). The first one I did up was back in the 1970’s, more as a “look at this” 
rather than a real product. 

Since they are running directly at VHF / UHF you can get better far removed phase noise
with then compared to an oscillator multiplied from a (much) lower frequency. That is the
basis for their “much better phase noise” statement. If you compared a VHF SAW to a
crystal oscillator running at the same VHF frequency (say 120 MHz) the SAW would not
have an advantage. 

Jitter is very much a function of the mask you use. If the mask starts very close to carrier
(say 10 Hz) and does not run very far out (say 10 KHz) the SAW isn’t going to look very 
good. If the mask starts at 10 KHz and runs out to 100 MHz, the SAW will have “low jitter”. 
It’s all going to depend on what your system is sensitive to.

The big advantage to an ovenized SAW is that it *can* have an EFC that will lock it up.
The tempco of a SAW without the oven makes “full range” EFC difficult ( which degrades
performance ….). 

All that said, people *do* make VCO’s with very low phase noise at frequencies even 
higher than what you can hit with a SAW. If you are trying to do a very low noise microwave
“something”, they likely will be part of the mix.

In direct answer to the question about “do they have any use in timing?”. Yes, I have designed
them into systems in the (distant) past. 

Bob



> On Feb 25, 2020, at 8:46 AM, John Moran, Scawby Design via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Do these devices have any use in the TimeNuts community?
> 
> https://www.electronicsweekly.com/news/products/digital-integrated-circuits/iqd-launches-ocvcsos-2020-02/
> 
> They claim lower phase noise and noise floor and jitter.
> 
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