2 stage trasimpedance problem

Discussion in 'The Projects Forum' started by priyanmanish, May 11, 2012.

  1. priyanmanish

    Thread Starter New Member

    May 8, 2012
    1
    0
    Here is my simple circuit
    I need a 2 stage transimpedance amp with
    Gain: 6M times (1nA will result in 6mV output)
    Rise time: 400nsec worst case
    Frequency response: 100KHz to 500KHz

    So I have calculated the resistor values arbitarily(R1,R2,R3) for producing a Gain of 6M.
    I am having difficulty finding the capacitor values in order to maintain a 6M gain and also the rise time must be < 400 nsec.

    I am a newbie and need help with the formulas in understanding this. I am ot sure if Iam missing out on some basic points.
    I need to have the value of C2 without compromising the gain.

    Please help me with this.
    Thanks in advance
     
  2. #12

    Expert

    Nov 30, 2010
    16,252
    6,749
    I see a slew rate proble. The OPA355 can do 360 volts per microsecond. In 400 nsec, it can only move the output by 1.1111 millivolts.
     
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