On the use of OPamps for PMT output stages. Richard is correct, the amplifier is usually a few discrete transistors... because... really, really fast OPAMPS and Burr Brown has some fast ones... are way too slow to avoid integrating to PMT output in pulse mode.
I doubt that any LMXXXX chip opamp will do too much if the pulse is below a few hundred nSecs. Check the frequency at which you get unity gain. These are typically a couple MHZ for TTL or slower applications.
ECL chips, (Motorola has(had)a line..)and some of the newer ones for the digital wireless technology applications, are in the right rise time regime. I think MAXXIM also has some.
What you will need for the preamp, is an emitter follower input stage, to get a low impedance output. You will need to be in the 75 to 50 ohm range. Cables and terminations have to be well matched, since line length can affect what appears at the amplifier input.
You also need a pretty fast scope....usually 200 -500 MHz minumum to get the rise time below 700ps. So you can actually tell what your amplifier is doing. Check the rise time of the front end... otherwise you will only measure the response of the scope, not your cct.
Final point, there used to be a sweet lil cct in the LM555 app notes for TTL pulse stretching. Probably can find a similar one with the ECL chip app. notes. Basically is just a fast rise... hold for a few... then fall cct.
Dave Cooper
Created on Saturday, June 16, 2001 1:18 AM EDT by David Cooper