# Driving Avalanche Photodiodes (PCBs)

I am using Avalanche Photodiodes and I was told that they use a much higher voltage then standard photodiodes and I was wondering if I need a High Voltage PCB to drive them? I am currently just using Ardunios but I'm guessing that I will need something better?

I am using 8 FirstSensor AD500-9-8015 avalanche photoiodes.

Also if I was using photomultipliers would I need a different PCB to run these to get the optimum output?

• Your question contains a usage of the term "PCB" that makes it somewhat ambiguous. I believe you mean "circuit", but I'm not sure what picture would come into your head if the answer was "no" -- how could a component not need its own interface circuit to function? Please edit your question if this comment makes sense and you've come to agree with it. – TimWescott Feb 13 at 15:41
• Please mention that it is a FirstSensor AD500-9-8015, too -- you gave a catalog listing, but this site discourages things that smack of "shopping", and links will rot. A manufacturer and part number will make the question much longer lasting. Again, please edit your question. – TimWescott Feb 13 at 15:44
• Could you say what you actually want to do with this? The part you're showing is for detecting very small amounts of light very fast (100MHz, oh my!); there are a lot of problems that can be solved with a much more ordinary PIN photodiode and transimpedance amp, with no voltages over 5V on the board. – TimWescott Feb 13 at 16:01
• Did you want to define your specs or us? – Sunnyskyguy EE75 Feb 14 at 3:43

## 2 Answers

The AD500-9-8015 has the amplifier built in, you need to supply the appropriate Vcc which in the datasheet can range from 4.5V to 11V for proper operation. The bias pin needs 100 to 240V:

This detector requires +4.5 V to +11 V voltage supply for the amplifier and a high voltage supply (100-240 V) for the APD. The internal APD follows the gain curve published for the AD500-9-TO52-S1 avalanche photodiode. The transimpedance amplifier provides differential output signals in the range of 200millivolts differential.

The photo multiplier needs an external amplifier circuit for proper operation

• Note that the part wants a bias voltage from 180 to 250V -- see figure 1 in the actual data sheet. – TimWescott Feb 13 at 15:38
• So the detector requires +4.5 V to +11 V voltage supply for the amplifier and high voltage supply 180-250 V for the APD. Does this mean I would need a PCB like frogpedals.com/index.php/product/… to power the Avalanche Photodiode? – James Feb 13 at 15:51
• The Frogpedals board would work as a lab setup, but note that it delivers about 40 times as much current as your worst-case need (see my answer -- $\frac{20\mathrm{mA}}{500\mu\mathrm{A}} = 40$. – TimWescott Feb 13 at 15:57
• Give the level of knowledge you're showing in your questions, I would like to point out that you should look around for a sensor circuit that includes the part you want, or does what you want to do. You're diving into the deep end of the pool, and the voltage levels mean that there's small sharks in there. – TimWescott Feb 13 at 15:59

"I am told" -- this is unnecessary. You need to read the actual data sheet of the part (as opposed to the catalog listing you gave).

That data sheet calls out a bias voltage from 100V to 250V (see the first line, second paragraph, "Applications Notes" section, first page).

So, yes, you need a circuit that is either supplied with 200V (I'm going to use "200V" to mean "100-250V" here), or that generates 200V. I could not find a rating for how much current you need to supply at 200V, but the data sheet calls out a 390k$$\\Omega\$$ current limiting resistor to protect the transimpediance amplifier. This would have a short-circuit current of $$\\frac{200\mathrm{V}}{390\mathrm{k}\Omega} = 513\mu\mathrm{A}\$$. That's just 1/10th of a watt of power, so it's within the realm of possibility to generate it on-board from your 5-11V VCC, using a square inch of board space or less for one receiver (you don't state whether you want eight on one board, which would allow you to make a central HV supply, or need eight separate boards).

A photomultiplier tube also needs high voltages, and signal conditioning -- I'm not sure what they operate at, but I would expect it's at least in the hundreds of volts. So you'd have the same issues of voltage generation.