Electronics > Projects, Designs, and Technical Stuff
Consequences of SiPMs in parallel
LoveLaika:
--- Quote from: jmelson on June 22, 2020, 04:46:11 pm ---
--- Quote from: LoveLaika on June 22, 2020, 03:26:26 pm --- Based on your experience, can a good pre-amp compensate for the increased capacitance and dark current from the SiPMs? If so, what characteristics did you look for when choosing a pre-amp?
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Yes, up to a point. The idea is to make the preamp input impedance as low as possible. We used an LMH6714MF as the first stage amp, with a 900 Ohm feedback resistor paralleled by a 1.8 pF capacitor. This gets pretty good rise and fall times, but not good enough for a fast scintillator. We ended up back with photomultiplier tubes.
Jon
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Thank you for your reply. If I may, I'd like to get your opinion on something. It's about the multiplexing scheme that Duak referred to:
http://www.sensl.com/downloads/ds/TN-Signal_Driven_Multiplexing_Method.pdf
I'm running some simulations in SPICE with some models (sorry, can't show the models due to reasons), but from what I understand, when you pulse SiPMs, they turn on/off the diodes to pass their pulse along, and it gets summed up along with the other voltages. This isolates the SiPMs from one another, and this also keeps their pulse shape, but this scheme reduces the magnitude of the pulse significantly, and when you pulse multiple SiPMs together, the timing gets a little slower. For example, if an ideal SiPM fast-out pulse produces a sharp pulse of 170 mV, then a multiplexed SiPM produces a same-shape pulse reaching 80 mV. It's also faster too.
Multiplexing like this seems to have advantages in speed, but the magnitude is significantly reduced. Question is, how do I magnify such a small signal?
Marco:
--- Quote from: LoveLaika on June 18, 2020, 06:31:13 pm ---If so, what op-amps would you recommend?
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Do you really need a TIA at all? It will represent a relatively small Rs and thus provide the fastest recharge time, but do you need that? The great thing about avalanche devices is precisely that they have enough gain you can often just use a resistor and simple voltage amplifiers, which is much simpler than TIAs.
Also why don't you use the fast output? With Rs = 0, you get fast recharge time too. Connect a common emitter amplifier to each fast output and connect the collectors together to sum the results for the individual SIPMs.
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