[time-nuts] DMTD mixer question

pablo alvarez pabloalvarezsanchez at gmail.com
Wed Dec 3 15:50:16 UTC 2008


Hi,

I have been looking at several Dual Mixer Time Difference designs. As
far as I know the basic architecture is based on generating a tone
with an small frequency offset respect to the nominal clocks
frequency, analogue mixing of the clocks, low pass filtering, then a
slow zero crossing detector and finally a time interval counter or
time stamp unit.

I have this naïf question: would not it be better and simpler to use
directly an ECL D flip-flop as a mixer instead of an analogue one? I
suppose analogue mixers are preferred because they provide with a
better "differential tempco", but using ECL logic can provide also
with a good tempco.

What is your experience?


Cheers

Pablo



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