MPPC amplifier

I'm looking into low-light detection using MPPC's and I am testing using the Hamamatsu C12332-01 evaluation module. I am looking for general hints, tips and tricks to maximize the performance of these modules.

We'd like to have a measure for the total amount of photons collected every 20-100ns (exact timing t.b.d.)

One of the things that surprised me was that the frontend of the evaluation board uses an OPA846 in a non-inverting (voltage) amplifier configuration; and not as a transimpedance amplifier. What would be the benefit of that?

Thanks!

Reply to
Fitzgerald
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It's not uncommon when using a slowish amplifier (60 MHz @ min stable gain, 625 V/us) with a much faster transducer. The op amp can't control its summing junction adequately in the inverting configuration in that case, leading to measurement nonlinearity.

Also the MPPC's output is far from shot noise limited (due to the high gain and fixed charge per segment), so you don't care much about the Johnson noise of the load resistor (probably 50 ohms).

If you want a fixed, finite integration time, I recommend using ping-pong gated integrators. Each one integrates maybe 60% of the time, and you overlap the two so that at least one is integrating at all times. You can make them closer to 50% duty cycle if you like, but you run the risk of missing stuff if you have both switches transitioning simultaneously, i.e. at exactly 50% duty cycle each.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

Thanks! I was thinking about integrating short intervals (10-40 ns) and then summing in software if I needed longer integration times.

I like the idea of a ping-pong integrator, but I don't understand why I should overlap their integration periods. I would assume that this would lead to blurring of consecutive samples. Wouldn't it be better to have the integrator be high-Z on its input when it is not integrating? Any charge being generated will just accumulate during the dead-time between the ping-pong when both integrators are off.

Reply to
Fitzgerald

Slowish?

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maybe you just typed wrong, the above says 400 MHz at a gain of 10.

George H. The op amp can't control

Reply to
George Herold

Ah, okay, assumed that the 400 MHz number was the GBW. Still way too slow to be safe as an inverting TIA with a MPPC.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

Perhaps the devices take a finite time to move from integrating to non-integrating, and you want to put half the signal that lies on a transition into the earlier interval, and the other half into the later interval.

A finite transition time from integrating to not integrating will have that effect too.

Perhaps, if it works that way. Summing junctions that move away from the default voltage can do odd things.

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Bill Sloman, Sydney
Reply to
bill.sloman

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