They are relevant when a high input impedance buffer is used making it
easier to add series/shunt overload protection. Protecting against
400 volts and higher is feasible this way.
Adding overload protection to a 50 ohm input is an interesting
challenge but it can be done. Precede the 50 ohm termination if used
with a current driven diode bridge. The current then determines the
maximum input voltage which can be passed to the 50 ohm termination
and following circuits. Check out the design of the Tektronix 7A29
vertical amplifier and 485 oscilloscope for examples were this was
done.
http://w140.com/tekwiki/images/2/20/7a29_input_amp_schem.png
On Tue, 11 Apr 2017 08:22:14 -0400, you wrote:
I have a really naive question: how can picoamp leakage parts be relevant in low impedance input pulse conditioning to an interval counter?
Tim N3QE
They are relevant when a high input impedance buffer is used making it
easier to add series/shunt overload protection. Protecting against
400 volts and higher is feasible this way.
Adding overload protection to a 50 ohm input is an interesting
challenge but it can be done. Precede the 50 ohm termination if used
with a current driven diode bridge. The current then determines the
maximum input voltage which can be passed to the 50 ohm termination
and following circuits. Check out the design of the Tektronix 7A29
vertical amplifier and 485 oscilloscope for examples were this was
done.
<http://w140.com/tekwiki/images/2/20/7a29_input_amp_schem.png>
On Tue, 11 Apr 2017 08:22:14 -0400, you wrote:
>I have a really naive question: how can picoamp leakage parts be relevant in low impedance input pulse conditioning to an interval counter?
>
>Tim N3QE
