[time-nuts] sine to square wave converter

bruce at ko4bb.com bruce at ko4bb.com
Thu Jul 10 14:40:55 EDT 2014

> On July 10, 2014 at 10:55 AM EWKehren at aol.com wrote:
> As part of the FE 405 B project a separate output circuit is in the works.
> The universal controller and auxiliary board are the same as used in the
> FE5680A GPSDO but because of the very low ADEV a separate circuit board that
> divides by three and has also two ground isolated transformer outputs is in
> the works.The question is what is the best sine to square wave converter
> with the lowest ADEV contribution. I am looking at Bruce's circuit using the
> ADCMP600. Any other ideas?
> Thanks Bert Kehren
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Although  CERN likes that circuit for its ruggedness and versatility its a
little noisier than some alternative circuits.

Currently Linear Technology's sine to square wave devices with selectable
filtering (LTC6957 series) are better in that they are a closer approximation to
the ideal zero crossing detector.
Failing that the next best is perhaps an AC coupled  (both at input and between
emitters) differential pair of 2N3906's or similar.


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