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

Bob kb8tq kb8tq at n1k.org
Fri Sep 8 22:29:16 EDT 2017


Quick and simple on the XOR doubler:

Buffer up your square wave. Output goes direct to one input of the XOR. Other
input goes through a filter to give you a phase shift. Low pass is one option. Band
pass is another option. Both benefit from being tunable. Net result is that you can get
the sub-harmonics down to about the -40 db level. Phase noise will floor out at whatever 
the floor of the logic you use is. ( = it’s not magic) 


> On Sep 8, 2017, at 9:59 PM, Chris Caudle <chris at chriscaudle.org> wrote:
> On Fri, September 8, 2017 5:15 pm, Charles Steinmetz wrote:
>> 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.
> I think there have been several discussions on squaring circuits, I was
> more interested in the XOR doubler.  That seems like it might be pretty
> simple to implement since I will have power supplies for CMOS gates easily
> available.  I don't remember seeing discussions on that technique.
> -- 
> Chris Caudle
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