God morgon, On Sat, 9 Jan 2016 23:01:31 +0100 Magnus Danielson <mag...@rubidium.dyndns.org> wrote:
> > A D-Flipflop is a rather weird mixer. I have not done the calculation, > > but i'm pretty sure that the output is not exactly what you'd expect > > it from a normal mixer (namely having half the energy at the frequeny > > difference and half at the sum). > > It's not that wierd. It's a sampler, and thus it acts like a mixer as if > the signal is spikes, which is just another interpretation of the > Nyquist frequency aliasing. Meta-stability however creates an > "interesting" aspect. Ah right! That also explains my uneasy feeling about it :-) It's relatively easy to get around metastabilitiy: just add another couple of D-flipflops in series. Unfortunately, that will only fix the metastable lingering in-between. It wont fix the edge being at the wrong time. > A third digital phase-detector is the SR flip-flop. It avoids the 180 > degree phase property (really a triangle wave signal) of the XOR, but > give a 360 degree phase sawtooth. This can be helpful in certain lock-up > conditions. SR-flipflop? Are you refering to the JK-FF phase detector or the PFD? > The phase-frequency detector of the 4046 and the like has additional > flip-flops to remember slipped cycles and forcing the frequency to > regain that. Those provide a strong frequency lock mechanism with a > phase detector in one. Interesting... i have to look into the old datasheets. > > Single gate chips better than multi gate chips. > > (no interference through the power supply of the different sub-parts) > > Well, you should wire the other parts into passive mode. That would be a waste of good PCB space ;-) Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.