# [op amp - Gain current source - current reference]

I have a question about the formula to consider for calculation of the gain for the electronic bellow.

Thanks for your support.

• To formulate a gain relationship you need to show where the input signal is and where the output signal is. Commented Jun 18, 2020 at 12:53
• @Andyaka: Thanks for your reply. If I consider that my V input is the voltage across R1 and V output is the voltage across R3. Can I say that the gain is equal to R3/R1 ? Commented Jun 18, 2020 at 13:00
• No, it doesn't work like that - you need to show a voltage source as the input. There needs to be cause and effect. Commented Jun 18, 2020 at 13:08
• @Andyaka: So If I understand your explanation for my circuit schematic there is no real gain formula to use ? Are you agree with my point ? Thanks Commented Jun 18, 2020 at 13:12
• The current through R3 is 6.2 volts / 22 kohm or V(D1)/R2 as I explained in my answer on the previous question. Commented Jun 18, 2020 at 13:26