[time-nuts] sine to square wave circuits - performance data?

Bob kb8tq kb8tq at n1k.org
Wed Oct 4 11:01:31 EDT 2017


Hi

This gets into the “other side” of the whole comparator / squaring circuit test process. 
What matters for ADEV and what matters for phase noise at 100KHz offset likely are
not the same thing. A lot of circuits do quite well inside 100 Hz, but not so well above
that offset. 

Driving a 5V powered CMOS gate with 5.5V p-p does a pretty good job ….

Bob

> On Oct 3, 2017, at 10:11 PM, Mark Sims <holrum at hotmail.com> wrote:
> 
> I am using the simplest possible sine to square wave converter on my HP5313xA counter time interval calibrator...  a capacitively coupled HCMOS gate (74HC86) biased at VCC/2 with two 47K resistors as shown in the LPRO manual and Wenzel's squarer page.  I was not expecting anything good, but was pleasantly surprised.   Attached is a plot of the xDEVS using a TAPR TICC... TICC clock was a 5071A 10 MHz,  chA input was the squared output of the second 5071A output 10 MHz signal divided to 1PPS with a TADD2-mini.  The squarer prototype was built on perf board using a DIP packaged part.
> 
> An update on the calibrator project:  I have the PCBs on order and they have supposedly been shipped, but are taking their sweet time getting here from China (despite paying for DHL 3 day shipping).  But, it looks like I need to tweak the PCB since the rotary switches that I received do not match the samples that I got... grrr...   I have found a local guy that may be able to assemble the boards for a quite reasonable price and another place for a semi-resonable price.
> 
> The same PCB order also included the boards for the X72 rubidium interface.<cal.gif>_______________________________________________
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