[time-nuts] HP-531xx calibrator nearing completion

Neil neil at g4dbn.uk
Fri Sep 8 18:56:17 EDT 2017

I've used some LT1719s in a project to discipline a 100MHz OCXO using an 
HMC1031. They work really well in squaring up the 10MHz sine from my Rb 

Neil G4DBN

On 08/09/2017 23:15, Charles Steinmetz wrote:
> Chris wrote:
>> Mark Sims wrote:
>>> It takes a 10 MHz input,  feeds it through a sine-to square converter
>>> (using a biased CMOS gate)
>> Could you send me a snip of what that looks like?
> Depending on your application and its tolerance for jitter/PN, you may 
> want to use a fast analog comparator to do the initial sine-square 
> conversion.  The difference in jitter/PN compared to a biased CMOS 
> gate can be 10-20dB over a wide range of tau/BW (even worse if the 
> gate has a Schmidt trigger input, which has WAY, WAY too much 
> hysteresis for a sine-square converter).  I recommend the TLV3501, 
> LT1719, and LT1720 out of extensive experience with them.  These 
> comparators have just the right amount of internal hysteresis for 
> squaring a 10MHz sine wave, with 10MHz jitter around 10-15pSrms for 
> jitter bandwidths from 10Hz-5MHz.
> Of course, if your multiplier/divider chain has more jitter than a 
> CMOS squarer, it won't make much difference which squarer you use -- 
> so be careful with its design and construction.
> Best regards,
> Charles
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