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LOG114EVM: Adding a photodiode intensity preamplifier to shift the range

Prodigy 60 points

Replies: 11

Views: 808

Part Number: LOG114EVM

Dear experts;

In the frame of developing a low-light sensing experimental board, I recently acquired a LOG114EVM development board. With included components and the reference current source locked at 500nA, the default range is stuck between 10nA and 10mA, for a floor output voltage Vout of 1.15V.

My application uses a low dark current photodiode VTB1013BH, sensitive in the green region (0.3A/W) in photovoltaic mode. Dark current is at most 20pA while full illumination outputs 1uA (5 decades). To obtain a full response from the LOG114EVM board, I need a current amplification of 1000. Precision low bias current OPA2107 and 1% resistors are available, what kind of circuitry do I need to  feed the LOG114EVM a 1000 scaled current from the photodiode in photovoltaic mode?

  • In reply to Thomas Kuehl:

    Hello Thomas.

    Thank you very much for the file enclosed. This design will be tested as soon as we receive new components. This question may now be closed and flagged as resolved. The dedication of the TI community is very much appreciated.

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