[time-nuts] Re: DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

[Erik Kaashoek]

Hi Magnus,
Yes, and it works very well, locking is easier as once locked it nicely 
stay's in lock, , even with a slow drift of either the DUT or the 
reference. As I could not find a bipolar capacitor the tuning potmeter 
has to be kept at the low side to avoid blowing the integration 
capacitor. Maybe a back to back series capacitor with pull down resistor 
is safer to use.
Will need to update the schematic to show the small improvements.

@Bob,
You mentioned "dual supplies with high voltage" for the first gain 
opamp. How much impact would dual voltage bring as its a pain to implement.
I understand everything gets ground reference and you loose the noise of 
the buffer opamp but as the first gain opamp is in differential mode for 
its input it does not see the noise of the buffer opamp. Or am I making 
a mistake?

On 10-7-2022 2:02, Magnus Danielson via time-nuts wrote:
> Have you attempted doing a PI-loop as I've suggested?