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ADPD2210 Interfacing with TIA

Question asked by disconomer on Jun 14, 2017
Latest reply on Jun 15, 2017 by JinoL

Hi,

I have an existing photodiode design which utilises a single supply TIA made from an ad8615. The metal can of the PD is hooked up to a reference voltage of 2.5V, as well as the non-inverting input of the amp. The other pin of the PD goes to the inverting input, thus the "no light" voltage sits at 2.5V, and the maximum peak to peak output of the amp approaches 2.5V.

 

I would like to replace the aforementioned photodiode with a combination photodiode / ADPD2210 amplifier, but i'm a little confused about the CRO output I am seeing, and how best to hook it up to the TIA. When I use the approach in figure 26 of the datasheet, with the same 2.5V going into the non-inverting input of the TIA, and the output of the ADPD2210 going into the inverting input of the TIA, it seems like i'm only getting about ~1.2V peak to peak before the waveforms distort. The "no light" voltage is about 1.2V

The ADPD2210 amplifier works nicely insomuch as the waveforms look pretty good, but I would like to achieve the 2.5V peak to peak so that it will work nicely with the rest of my design.

Can anybody suggest anything here? Should I be using the "ref" pin of the ADPD2210 and tie that to 2.5V?

Thanks in advance...

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