Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Measuring Pulsing Current Output Average From Photodiode

  1. Jul 28, 2016 #1
    Hello all,

    I will be using a photodiode to measure optical power. The photodiode will convert this power into a current. The optical power will pulse rapidly in 15 ns periods with a 5 ns on-time (at full amplitude) and a 1 ns rise and fall time. I am looking for an analog averaging solution, i.e. an op-amp circuit that would give voltage outputs, say, every 1 us that are equivalent to the average voltage over the past 1 us. Ultimately, I need to be able to read the average voltage (proportional to an optical power, of course) every 5 us, but I am interested in oversampling at a rate of 5X in order to ensure I am not missing pulses in my pulse train and getting inaccurate readings. I have looked into "fast integrator op-amp" circuits, but I am still unsure if that will do the trick. Any suggestions would be greatly appreciated.

    Thank you!
  2. jcsd
  3. Jul 28, 2016 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    Sounds like a fun project. Is your photodiode at the end of a fiber? How is it picking up these light pulses?

    The pulse width that you describe is fairly short, so you will need a specialized photodiode detector, IMO. What do you have in mind so far? And the first stage or two of the detector will not be jellybean opamps -- they should be fairly high speed detector amps, it would seem.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted