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Current limiter for TIA, realizing dc current source

  1. Jun 7, 2016 #1
    Problem:

    my photo diode recieves pulses of width 10ns-150ns and repeating at rate of 1Hz-50KHz

    the current from photo diode depending on incident light can go from 10nA-100mA, so i have two photo diodes to cover the dynamic range, what i want to do is limit the current from a photo diode to 5mA lets say in one channel

    Approach Followed:

    in search i found some thing similar to my need here
    iXo2X.png

    the patent claims: in the picture the current sources 30 and 38 are the maximum current at which the TIA saturates, as soon as the TIA saturates, the schottky bridge isolates the TIA from source,

    i have less idea whether the patent circuit can work for pulsating current, but when i tried the results were nice

    4P66L.png

    Design Problem:

    how to select the schottky diode and also the pJFET for much better response

    if you see schematic i have given a trail of pJFET of all available with LTspice, and same with schottky

    How to realize 30 and 38 on practical circuit ?, how can i create stable dc current sources ?
     
  2. jcsd
  3. Jun 7, 2016 #2

    CWatters

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  4. Jun 7, 2016 #3

    CWatters

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    Actually now I've read you post again... Are you after a current source/sink or a current limit? They are different.
     
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