Hans Hans Rosenberg wrote: > Hi Bruce, > > Thanks a lot for all the input. > > Do you have any figures on the noise voltage on a led? A good buried zener > reference does 100nV/rt Hz, what does a led do? > > You mention that an amplitude control mechanism influences phase noise. Are > you suggesting that a good amplitude control is better than turning off the > active device for some time each cycle? > > There is some debate about this in the literature. > I started having a close look at the driscoll design. It looks really nice. > It seems much more elegant than what I was trying to do. I do have one > question about the AGC circuit. The tune-voltage must be kept in the middle > of the supply, otherwise the amplitude control loop will modulate the overall > capacitance of the capacitive attenuator. The input capacitance doesn't vary that much if the attenuator is correctly proportioned: http://www.karlquist.com/97bri.pdf > So this is critical to set correctly in practice. There probably is a good > reason why the current in the transistor is not changed to achieve amplitude > control. Do the capacitances in the transistors vary so much that they start > introducing more phase errors than when tuning a capacitive attenuator > correctly? Or is there another reason. > > > Thanks again for the nice input. > > Best regards, > > Hans Rosenberg > >
Bruce _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
