[time-nuts] Noise contribution of PLL on measuring phase noise

Thomas S. Knutsen la3pna at gmail.com
Wed Jun 28 06:29:07 EDT 2017


When measuring Phase Noise using PLL, what noise would be contribuded from
the PLL into the amplifier?
Lets say we disconnect the control voltage from the oscillator, shouldn't
the input stage of the PLL contribute some, altough miniscule part to the
total noise seen?
Would this noise be masked by the noise from the phase detector?

The reason for asking is that I'm trying to improve my PN measurement
Currently the PLL consist of a unity gain buffer made of TL072 before the
PLL filter, not unlike what Wentzel did in his amplifier. The PLL filter is
a low noise op-amp (OP27).


With Best regards, Thomas S. Knutsen.

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