Transimpedance Amplifier

Discussion in 'General Electronics Chat' started by Gibson486, Apr 11, 2014.

  1. Gibson486

    Thread Starter Member

    Jul 20, 2012
    199
    12
    What do you gain when you use an op amp like this...

    http://www.ti.com/product/opa380

    I always thought a transimpedance amplifier was just a configuration thing. However, this is specifically called an transimpedance amplifier....

    What makes this different from any other high bandwidth FET input amplifier?
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,539
    1,251
    It is built from the ground up to be a current to voltage converter of very small currents. Plus, it has an auto-zero servo.

    ak
     
  3. Gibson486

    Thread Starter Member

    Jul 20, 2012
    199
    12
    I am using it with this guy

    http://www.vishay.com/docs/81521/bpw34.pdf

    My circuit is figure 1, but with Vbias to gnd.

    Rfeedback is 100 ohms.

    What I do not get is why I get a full voltage swing up to 4.5V. According to the spec sheet, the photodiode can not even go up to 1mA. To get 4.5V, I would need over 25mA. Am I missing something?

    Edit: my pulses are at 20 Hz.
     
    Last edited: Apr 24, 2014
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