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discrete photodiode amplifier

Discussion in 'General Electronics Discussion' started by T8P1, Jan 31, 2011.

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  1. T8P1


    Dec 22, 2010

    I have to design a discrete Photodiode Amplifier with a flat bandwidth to 50MHz and a current input noise below 3pA/Hz. I get from the photodiode 0-50uA dc and 35pA ac.
    I split the ac and dc current to amplify them separatly. The dc part is no problem, but the ac part.
    My opinion is to amplify it with a jfet, think to try the bf862, with pnp cascode and a emitter follower.
    Have somebody a better idea?

  2. Laplace


    Apr 4, 2010
    Have you looked at the TI OPA847? It is billed as a wideband, ultra-low noise operational amplifier suitable for making a transimpedance amplifier for photodiodes. I've been trying to use it with a PIN photodiode as a high-gain sub-microsecond single event detector.
  3. T8P1


    Dec 22, 2010
    At first, the OPA847 looks nice, but its current input noise with 2.5pA/Hz is near the limit.
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