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OPA637: Circuit understanding Required

Karthick Venkatachalam
Prodigy 100 points
Part Number: OPA637
Other Parts Discussed in Thread: OPA404, OPA627

Hi Team,

We have used OPA637, OPA627 and OPA404 in one of our circuit. Input is from Si PIN photodiode S2506-02. Attached Snippet of the circuit. Can anyone explain in detail to understand the application?

  • 0
    TI__Guru 50756 points

    Hi Karthick,

    Since we don't have any details about your design and/or application requirements, it is difficult to comment.  Is there an issue with the circuit above? We need background information into your application, details of the signal characteristics you trying to measure, photodiode sensor expected current range, AC/frequency response requirements and detail information about your input signal and output requirements. Please provide a diagram showing how the photosensor is connected in the circuit above.

    Thank you and Regards,

    Luis

  • 0 in reply to Luis Chioye
    Prodigy 100 points

    Hi Luis,

    Input is from Photodiode and we have used Trans-Impedance amplifier to convert current into Voltage. Not sure on the Gain, it seems we are tuning the R3 values to meet the voltage (Extinction) is reading 10.7v (10.6 V-10.8V) and R15 is tuned to meet the voltage of Summation is reading between 11.8V to 12.1V. This is due to some alignment issues of photodiodes during assembly. I have marked the Input and output in the below image, can you explain the circuit flow and gain product of each circuit?

    Regards,

    Karthick V

  • 0 in reply to Karthick Venkatachalam
    Guru 140200 points

    Hi Karthick,

    this is a very strange circuit. Can you tell more about the application? How are the photodiodes illuminated?

    Kai

  • 0 in reply to kai klaas69
    TI__Genius 11775 points

    Hi Karthick,

    Can you tell me more about what you are trying to do with this circuit?  Does it have a problem you are debugging?  This is a large circuit, in order to help break it into blocks to understand it better, we would need to know what you are measuring or having a problem with.

    Regards,
    Mike