Sorry, having trouble picturing the circuit, mind explaining it in a bit
more detail? Add a netlist maybe?
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On Sun, 8 Jul 2018, 10:12 Tom Gardner, <tggzzz@...> wrote:
On 08/07/18 04:53, Ed Breya via Groups.Io wrote:
If you are concerned about setting or controlling the frequency, you can
drive the output stage instead from another with XO or a generator. My
preferred 74AC driver for fast, strong pulsing is the 74AC541, with eight
amplifiers that can be paralleled. Also, the pinout is excellent for this
sort of thing, layout-wise - all ins on one side, and all outs on the other.
My preference is 74LVC1G*, which have ~7ohms output impedance, 32mA
drive, and
work from ~1V to 5V albeit with different risetimes.
If you add a 143ohm series resistance and put three of those in series
(and
decouple them very well), then you get a clean 50ohm output. I can't
measure the
risetime; it is certainly sub nanosecond, another measure gives ~600ps,
and I've
seen a (poorly controlled) measurement of 300ps on a 1GHz scope.
