[time-nuts] OCXO PLL gains?

[Alex Pummer]

Hi Anders

look that

https://www.analog.com/media/ru/training-seminars/tutorials/MT-086.pdf

73

KJ6UHN Alex


On 2/1/2019 10:11 AM, Anders Wallin wrote:
> Hi all, is there are rule-of-thumb or simple paper/presentation of how to
> choose PLL-gains?
>
> I have a phase-detector that gives out a slope of roughly 1 V/rad, followed
> by an op-amp circuit with proportional, integral, and double-integral gains
> summed into one voltage [0, 3.3V] on the tune-pine of the OCXO ( +/- 0.6
> ppm pull-range, from datasheet).
>
> So far it locks with only P-gain, but the phase-noise (and ADEV) shows a
> 'bump' somewhere between 10 and 100 Hz offset from the carrier.
> I tried the integrator with a time-constant of 1/16Hz using R 100k  C 100n,
> but it wouldn't lock.
> The thinking was to put the integrator time-constant about where the
> free-running ADEV turns upwards from a 1/tau slope.
>
> So far I didn't enable the double-integrator - not sure if it's worth the
> trouble or not..
>
> thanks,
> Anders
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