[time-nuts] reference oscillator input circuit
John Ackermann N8UR
jra at febo.com
Wed Dec 8 13:05:13 EST 2010
I can confirm that -- that's where I found it (and my schematic in the
TADD-2 manual gives credit to Wenzel)!
I chose that design mainly because it worked over a wide range of input
On 12/8/2010 12:48 PM, Robert Darlington wrote:
> Just an FYI guys, I'm pretty sure the 3rd circuit down on the Wenzel page is
> identical to the input circuit for the TAPR TADD-2 frequency divider. The
> TADD-2 adds a transformer and load resistor. Schematic is in the manual
> On Wed, Dec 8, 2010 at 8:46 AM, John Ackermann N8UR<jra at febo.com> wrote:
>> Wenzel has some discussion and circuits at:
>> The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL
>> chip for squaring.
>> On 12/8/2010 10:31 AM, jimlux wrote:
>>> I'm looking for suggestions on a general circuit that can be used to
>>> receive an external frequency reference (nominally a real clean sine
>>> wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it
>>> into a "real clean" square wave. Galvanic isolation is a plus (a
>>> transformer or capacitor would probably do that).
>>> I was thinking about rummaging through the schematics for test equipment
>>> reference inputs (since they've already "solved" the problem, eh?), but
>>> any other ideas would be welcome.
>>> I've scanned the archives of time-nuts, and while we have a fair amount
>>> of discussion on how to square up the 1Hz (or 100Hz) in a phase
>>> noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has
>>> commented that you don't want to use a comparator. I have the papers by
>>> Dick, et al, and Collins, as well as all the others.. they tend to be
>>> looking at the low frequency problem, although the analysis is certainly
>>> I don't know that I'm looking for the whole multiple limiting stages
>>> scheme in any case.
>>> Oh, as far as performance.. Say the need is to not horribly degrade a
>>> good quality crystal oscillator... here's a typical set of specs:
>>> 76 MHz
>>> Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10
>>> sec, and back up to 2 E-12 at 1000sec.
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>>> and follow the instructions there.
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> and follow the instructions there.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts