[time-nuts] OCXO Voltage Input? (Bob Camp)

Dan Kemppainen dan at irtelemetrics.com
Fri Sep 5 08:50:46 EDT 2014

Hi Bob,

Being relatively new to this 'high end' time stuff, there's lots to
learn...   So, how much bandwidth might a typical OCXO have on the EFC
pin? My assumption is that it is very low, but I have nothing to back
that up.

If I had 10Mhz or some other high frequency on the EFC line, would a
typical OCXO respond to that?

The concern is that any HF noise on the power pins of the driving op-amp
might make it onto the EFC line. Of course most amps have good PSRR at
low frequencies. If the EFC pin only has low frequency response, there
shouldn't be an issue.

Are there any OCXO schematics out on the web, that one could study?


On 9/5/2014 7:02 AM, time-nuts-request at febo.com wrote:
> Hi
> The EFC pin *might* have a bypass cap on it. If you drive it with an op-amp an isolating resistor might be needed. If so, a couple hundred ohms is likely enough to stabilize the op-amp.
> In a closed loop / control loop setting, the noise on the EFC will be whatever the loop generates. As long as you stay with good quality op-amps and low impedances in your filters, things should be plenty quiet. 
> Things like EFC range, output frequency, phase noise, and intended use  / circuit would be needed to come up with more specific information. 
> Bob

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