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Transimpedance v integrating amplifier

Rajinder

Jan 30, 2016
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Hi,
I have attached a diagram of a photodiode connected to an opamp, this is an I to V converter or transimpedance amplifier, the current from the photodiode is converted into voltage by the feedback resistor.

I have also seen the same can be achieved using a capacitor in the feedback instead of the resistor. I believe the output voltage is the integral of the input current. I am not sure exactly how this works, can anyone help me to undetstand it.

Also is there any benefit of using one configuration over the other?

Its to be used in a smoke alarm.
Thanks in advance.
 

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Harald Kapp

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Nov 17, 2011
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can anyone help me to undetstand it.
You'll need some math.
Also is there any benefit of using one configuration over the other?
The transimpedance amplifier gives instantaneous values whereas the integrator gives, well, integrated value - kind of a low pass filter. Which circuit to use depends on your application:
  • fast response - transimpedance amplifier
  • noise suppression - integrator
 
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