[time-nuts] NCOCXO anyone?

David davidwhess at gmail.com
Thu Jul 21 23:22:14 EDT 2016

On Thu, 21 Jul 2016 18:47:24 -0700, you wrote:

>On 7/21/2016 4:56 PM, Nick Sayer via time-nuts wrote:
>> Oh my. That’s a bit more than I was originally considering
 What I had in mind was adding a DAC front end to an OCXO so that you could tune the EFC with serial commands rather than analog and calling that a product.
>20 years ago when HP was working on a so called "smart clock"
>GPS box, they decided to do what you said, use a DAC to
>tune the EFC on the E1938A oscillator.  I
>recommended to them NOT to try to do that, but they
>didn't listen to me.  At that time, it
>was nearly impossible to come up with a DAC, buffer
>amplifier, and voltage reference that didn't degrade
>the stability of the E1938A, which isn't even as stable
>as a 10811.  What you need to ask yourself is:  in
>2016, can I finally get analog components that are
>an order of magnitude or two better than what was
>available in 1996?  I don't know, without researching
>it.  Certainly, we can't depend on Moore's law coming
>to the rescue.  If anything, that works against analog
>IC's by obsoleting older analog processes.
>Also in 1996, phase microsteppers were already legacy
>technology and didn't have a good reputation for spectral
>purity.  Another non-panacea.

Increased integration has only helped insofar as you can attempt
designs which would have been prohibitive before.

I keep trying to come up with a charge balancing design but what about
Linear Technology's solution from back in 2001?

A Standards Lab Grade 20-Bit DAC with 0.1ppm/°C Drift

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