[time-nuts] Buffering a PPS signal

[Bob Smither]

On 05/18/2012 07:24 AM, Bob Camp wrote:
> Hi
> 
> For a 50 ohm buffer, you probably want something like 200 ohms in series
> with each output (4 buffers) or 400 ohms (8 buffers).

It may be worthwhile considering the gate output impedance as well.  For
example, for 5V AC logic driving a 50 ohm line the initial edge from the gate is
about 4V - which implies a Zo of about 13 ohms.  A 50 ohm buffer with 4 gates
would therefore use 187 ohms series resistors.

There is an app note attached here that discusses this:

  http://c-c-i.com/node/107

-- 
Bob Smither                                              Smither at c-c-i.com
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