[time-nuts] DMTD - analog multiplier vs. diode mixer ?

Charles Steinmetz csteinmetz at yandex.com
Tue Jan 5 22:55:19 UTC 2016

Poul-Henning wrote:

>My little HP5065 project is continually running into the jitter of
>my HP5370B counter which is annoying me, so I'm looking int DMTD.
>Everybody seems to be using traditional diode-mixers for DMTD,
>and to be honest I fail to see the attraction.
>Why wouldn't a analog multiplier like AD835 be better idea ?
>What am I overlooking ?

You could have mentioned any of dozens of popular analog multipliers, 
and the answer would have been, "because they are way too 
noisy."  The AD835 is also substantially noisier than diode mixers, 
but it at least begins to bridge the gap.  The folks at CERN have 
been improving phase detector S/N by averaging the output of several 
AD835s for the TPMON project, with promising results.  There is a 
preliminary report in "EUROTeV Report 2006-005-1."

See also:

RF-based electron beam timing measurement with sub-10fs resolution, 
A. Andersson and J. P. H. Sladen, CERN (EUROTeV Report 2008-015) 
[phase detector with 8x AD835 analog multipliers].

ANDERSSON, A. and SLADEN, J. P. H.: "First tests of a precision beam 
phase measurement system in CTF3" (Proc. PAC07).

A. Andersson, J. P. H. Sladen, CERN (Proceedings of EPAC 2006).

Best regards,


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