- Ask a related questionWhat is a related question?A related question is a question created from another question. When the related question is created, it will be automatically linked to the original question.
Original question:
Hi Kato-san,
The resistor value in the I/V stage is select to try to optimize the gain of the circuit while avoiding the non-linearity region of the op amp output near the negative supply. This circuit has the best noise performance by maximizing the gain of the first stage and minimizing the gain of the second stage (or even attenuating the output on the second stage). See this cookbook article about that:
http://www.ti.com/lit/an/sbaa333/sbaa333.pdf
Otherwise, the capacitor value is selected to create a simple first-order filter to attenuate out-of-band noise and reduce the bandwidth of the TIA stage to ensure stability given that the second stage usually has a capacitive element near the output.
This combination gives an fC of about 90kHz:
Please let me know if that answers your question.
Thanks,
Paul
