Analysis of weak optical signal amplification circuit, help needed! ! ! ! ! ! !

反倒是fdsf

Analysis of weak optical signal amplification circuit, help needed! ! ! ! ! ! ! [Copy link]

The above picture shows a two-stage amplifier circuit for weak light signals. PD in the picture is the photodiode S12915. I have three questions that I don’t quite understand. I hope you can help me answer them. Thank you.

1. R13 and R14 are both 10K resistors, which are connected to the two input terminals of the op amp. What is their main function here? I think the photodiode amplifier circuit does not need to add this resistor. As shown in Figure 1. Simple transimpedance amplifier circuit

2.What are the main functions of the resistors R16, R15 and C12?

3. How to choose the resistance and capacitance of the filter composed of R2 and C2?

呜呼哀哉

Yours is powered by a single power supply, and the NPN (NMOS) type input is not allowed to reach the lower power rail.

You should know the cutoff frequency of the first-order RC filter, depending on the bandwidth you set.

反倒是fdsf

Alas, published on 2021-9-10 08:59 Yours is powered by a single power supply, and the NPN (NMOS) input is not allowed to reach the lower rail of the power supply. You should know the cutoff frequency of the first-order RC filter. See you...

If reaching the lower power rail is not allowed, how should this range be selected?

baopodao

The operating range of the PD needs to be determined first before the range can be determined in a single-supply op amp.

呜呼哀哉

On the contrary, fdsf posted on 2021-9-10 10:16 It is not allowed to reach the lower rail of the power supply, so how to choose this range?

Sorry, I didn't read your AD8606 information this morning, so I made a mistake.

That op amp is an RRI op amp and does not need to be biased to the appropriate voltage.

This requires a stability analysis to see if your capacitor is sufficient for compensation. If not, the 10K resistor and the resistor below are combined with the parasitic capacitance of your photosensitive diode for compensation. Estimate the resistor below under different currents to adjust the compensation parameters.

反倒是fdsf

baopodao posted on 2021-9-10 13:53 First, you need to determine the operating range of the PD before you can determine the range in a single-supply op amp.

What is the scope of work of PD?

反倒是fdsf

Woohoo! Posted on 2021-9-10 14:27 Sorry, I didn't read your AD8606 data this morning, so I was wrong. That op amp is an RRI op amp and does not need to be biased to the appropriate voltage. This one needs to be...

I think it's interesting. This is the improved circuit diagram. They added a potentiometer to the compensation part of the original circuit diagram. I also attached the original diagram.