[time-nuts] Clock Driver Design

[John C. Westmoreland, P.E.]

Bob,

Totally agree.

24mA of drive at 3.3V is pretty nice in a small footprint for the parts we
are discussing.  Of course as you have pointed out you can drive them at 5V
too.

Mini-circuits is a good place to look too - especially for us hobbyists:

http://www.minicircuits.com/products/DesignerKits.shtml



73's,
John
AJ6BC


On Thu, Sep 26, 2013 at 3:05 PM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> How clean is your clock source? If you have something that is -150 dbc at
> 1 Hz, then you probably need some fancy analog gizmos. If you can make do
> with "only" -110 to -120 dbc/Hz at 1 Hz, then properly driven LVC CMOS will
> do just fine. That's true for a square or a sine output. Since you pretty
> much can't find an OCXO better than -120 at 1 Hz, I'd bet you'll be ok. 5
> volt logic will be a little more quiet than 3.3V. More or less faster is
> quieter as long as you stay with saturated silicon CMOS. Change materials
> and all bets are off.
>
> For square wave cable drive you can parallel up a couple of the '125 or
> '126 gates to get how ever much power you want to put into the cable. You
> can source or load terminate (or both). If you source and load terminate,
> your logic levels will be 1/2 the output. With either source only or load
> only termination you can get full swing logic levels. More drive will
> always be required with load termination (you are putting current into 50
> ohms).
>
> Logic IC's are cheap, easy to use, and simple to find. A low voltage
> single supply drives them and they aren't current hogs unless heavily
> loaded. What's not to like?
>
> Bob
>
>
> On Sep 26, 2013, at 1:28 PM, Tom Minnis <Tom_minnis at att.net> wrote:
>
> > I am looking into various degrees of craziness.  The source is CMOS and
> there are plenty of 1 in to N out parts designed to drive clocks on a PCB
> but not much is said about driving clocks on to a random length of coax to
> another piece of equipment and what additional precautions that might
> warrant.  I am also considering making a sine wave output and maybe other
> frequencies.
> > Tom
> >
> > On 9/26/2013 4:34 AM, Bob Camp wrote:
> >> Hi
> >>
> >> Standard high speed CMOS logic works pretty well. How crazy are you
> trying to get?
> >>
> >> Bob
> >>
> >> On Sep 26, 2013, at 1:48 AM, Tom Minnis <Tom_minnis at att.net> wrote:
> >>
> >>> I am working on a small clock distributor and wanted to get some ideas
> on what works best for 10MHz and 1PPS driver circuits.  I remember sifting
> through the archives a year or so ago and tripped on some discussion of
> this but I can't find it anymore.
> >>> Tom
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