Electronics > Projects, Designs, and Technical Stuff

Ultra low power, clean 30V power supply + ultra low power high speed comparator?

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2N3055:
These guys made front end that would use something about 60uA..
Is that good enough.. ?
Also a portable battery powered unit..

https://aisberg.unibg.it/retrieve/handle/10446/77221/126298/TDUnibg1002866.pdf

Spirit532:
Their choice of opamp is not particularly ideal - my prototype uses the Micrel(now Microchip) MIC860, which has a bandwidth of 4MHz and a slew rate of 4V/us while only consuming 40uA. Faster, lower noise, lower power.
Their frontend(transistor-based, as suggested earlier here) consumes over 1.5mA in total, which somewhat crushes the point of having an ultra low power opamp.
I was thinking of using another MIC860 as a comparator with an adjustable threshold voltage(just above noise), with a bit of pulse stretching through feedback. Rise and fall times don't really matter in this case, since it's only going to be triggering a rising edge interrupt.

The real issue here is the power supply - say we have a budget of ~80uA for the amplification and "digification" of the signal, and another 50-80uA for the power supply. How do we get a clean, 28.5-33V(depends on the chosen SiPM, but that covers basically all of them) supply that, at no(or very little, nA) load would give us less than 10mVp-p of higher frequency noise(above 1kHz), and less than less than ~20-30mV of ripple?
The current consumption issue mainly sits in the realm of the power supply.

Vgkid:
While not geiger mueller, have you thought about modifying an older epd. The ones we have at work last some time on a single aa batery.

Spirit532:
That's like suggesting I buy a bicycle and turn it into a chair instead of building a table...
And FWIW, their sensitivity is 2-5 orders of magnitude less than the crappiest GM tubes. Scintillators have 2-4 orders of magnitude higher sensitivity than the best GM tubes.

Marco:

--- Quote from: Spirit532 on June 29, 2019, 08:42:15 pm ---A cascode setup would require quite a serious supply voltage and current to swing an external mosfet
--- End quote ---
Don't see why, a simple BSS123 should suffice at 3V. You won't be switching a whole lotta current. Use a low noise avalanche diode for the upper leg of the feedback divider.

--- Quote ---The fast output is only really useful for single-photon counting applications, here we're counting thousands to millions of photons(depending on particle energy) as an analog signal(see below).
--- End quote ---

It also seems useful for very high counts, if high energy photons strike the scintillator every say 10 ns you can still detect that. On the slow output those pulses pile up, the fast output will gives distinct pulses. You essentially get a well designed CR pulse shaper for free. That said, to detect pulses that fast you need even more bandwidth, so for low power and low counts I guess it doesn't make much sense.

TLV7011 seems the most appropriate comparator to me, increase the anode resistor to say 220 Ohm and the pulse should last long enough for it.

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