[time-nuts] 4046 replacement

Magnus Danielson magnus at rubidium.dyndns.org
Wed Apr 18 18:15:48 EDT 2018


Hi,

On 04/18/2018 10:57 PM, Charles Steinmetz wrote:
> Rick wrote:
> 
>> The book is incorrect.  A patent issued in 1976 (US4023116A)
>> covering the Fairchild 11C44 developed by Eric Breeze predates
>> the EDN article by several years.  I still remember the big
>> splash the 11C44 made when it was introduced in 1976. The Fairchild
>> ECL data book had a famous graph comparing it to the MC4044
>> in the dead zone.
> 
> The attached graph is the one I remember.  Note that, while the 11C44
> was better than the MC4044, neither one was really very linear near zero
> error.  Good multichip PFD designs of the era outperformed both of them.

Gardner thrown at them and suggested to use a mixer instead, as it has
better performance.

The real benefit of the 4044 and 4046 lies in that they where CMOS
devices and integrated well with other CMOS devices, and could help to
make designs more compact. If fills a purpose, but does not necessarily
give you optimum performance.

BTW, as you add noise to the signal, much of the behavior of the
triangle or sawtooth shape of the phase-detector average out to that of
a sine, which is no better than that of a mixer, but what happen in the
process is that the phase detector gain changed, and thus the loop
parameters. If you use a mixer, the phase detector gain becomes less
dependent on the S/N and thus a more stable system behavior.

Cheers,
Magnus



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