ultrafast amplifier?

[jack]

Hi,
I'm trying to find a schematic to build a small amplifier that will
take pulses with rise times of 1 to 3 ns and around 10 ns decay time
of only a few mV and amplify this up to 1 or 2 volts while not
loosing the rise/fall times. The pulses come from a photomultiplier
tube and maintaining the shape of the pulse is important. I'm not
interested in counting as yet,so I only need an amplifier. Does anyone
have any suggestions on how to approach this,or tips,or where I could
get schematics for this? Any help is appreciated. thanks jk

 

[Rene Tschaggelar]

Hi,
I'm trying to find a schematic to build a small amplifier that will
take pulses with rise times of 1 to 3 ns and around 10 ns decay time
of only a few mV and amplify this up to 1 or 2 volts while not
loosing the rise/fall times. The pulses come from a photomultiplier
tube and maintaining the shape of the pulse is important. I'm not
interested in counting as yet,so I only need an amplifier. Does anyone
have any suggestions on how to approach this,or tips,or where I could
get schematics for this? Any help is appreciated.

Just in case you have sufficiently low impedance : the MAR-6 of minicircuits
is a 2GHz AC amplifier delivering 20dB gain.
Take this one to start with and perhaps have another MAR-7 or MAR-3.

Rene

 

[Ken Smith]

Hi,
I'm trying to find a schematic to build a small amplifier that will
take pulses with rise times of 1 to 3 ns and around 10 ns decay time
of only a few mV and amplify this up to 1 or 2 volts while not
loosing the rise/fall times. The pulses come from a photomultiplier
tube and maintaining the shape of the pulse is important. I'm not

Why is it "volts" when it is from the anode of a PMT? I would expect the
signal to be a current or charge.

Basically, you need several stages with RF transistors in them to get from
1mV to 1V. You need a moderately stout Schottky diode on the input to
protect against the 1000V spikes that will happen when some fool plugs or
unplugs or just touches a working system.

I'd look at transistors like the Philips BF992 for the second stage.

I'd worry about using such a device at the input because of its ESD
sensitivity.

 

[Ban]

Hi,
I'm trying to find a schematic to build a small amplifier that will
take pulses with rise times of 1 to 3 ns and around 10 ns decay time
of only a few mV and amplify this up to 1 or 2 volts while not
loosing the rise/fall times. The pulses come from a photomultiplier
tube and maintaining the shape of the pulse is important. I'm not
interested in counting as yet,so I only need an amplifier. Does anyone
have any suggestions on how to approach this,or tips,or where I could
get schematics for this? Any help is appreciated. thanks jk

This is what I used for a front-end with protection circuit. I don't know
about the multiplier output impedance so you have to scale the current
sources up or down together with the resistor to gnd, or maybe can leave it
out all together. Make the 1st stage gain 10-12dB to get low noise and high
bandwidth by lowering the load impedance as much as possible. You can also
control the second gate with a DC-servo to get stable gm with temperature.


+-----------+---+-+----------------------o+5V
| | | C|
.-. .-. | C|
10k| | |<-+ C|
| | | | +-------+
'-' '-' |
| | |
| | |
| | |
+-|<--+-->|-+ +--||-+ dual gate HEMT-FET
| | | ||<-
o-+---+ Schottky +-+---)--||-+
| | | | | |
C| +->|--+--|<-+ | | |
C| | | | |
C| | | | |
| | | | +---+
.-. .-. .-. .-. .-. |
| | | | | | | | | | ---
| | 10k| 3k3| | | | | ---
'-' '-' '-' '-' '-' |
| | | | +---+
GND | GND | |
+-----------+-----+---------------------o-5V
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de

ciao Ban