kender
Advanced Member level 4
max471 ltspice
Colleagues,
I need to convert a small DC current into voltage. One of the ways is to use an opamp circuit often called transimpedance amplifier. The problem is that (1) the current I need top sense is always positive, (2) transimpedance amp is inverting (Vout = -Rf * Iin the feedback is negative) and (3) I don’t have a negative supply rail. On the positive side, my OpAmp has Rail-to-Rail (RR) inputs and outputs.
I want to connect the positive input of the OpAmp to the positive +5V supply instead of ground (see the circuit diagram below). I think that the output then will be Vout = Vcc - Rf * Iin > 0 for my range of input currents. Do you think that this can work?
Thanks,
Nick
P.S.
This post is loosely related to this one
Here's a 3D animation (!) of the transimpedance amplifier https://engineering.dartmouth.edu/3Dcircuits/animations/currentamp.html
Obviously, this circuit can be easily prototyped and experimented with. But at the moment I have to do a “paper design”.
Colleagues,
I need to convert a small DC current into voltage. One of the ways is to use an opamp circuit often called transimpedance amplifier. The problem is that (1) the current I need top sense is always positive, (2) transimpedance amp is inverting (Vout = -Rf * Iin the feedback is negative) and (3) I don’t have a negative supply rail. On the positive side, my OpAmp has Rail-to-Rail (RR) inputs and outputs.
I want to connect the positive input of the OpAmp to the positive +5V supply instead of ground (see the circuit diagram below). I think that the output then will be Vout = Vcc - Rf * Iin > 0 for my range of input currents. Do you think that this can work?
Thanks,
Nick
P.S.
This post is loosely related to this one
Here's a 3D animation (!) of the transimpedance amplifier https://engineering.dartmouth.edu/3Dcircuits/animations/currentamp.html
Obviously, this circuit can be easily prototyped and experimented with. But at the moment I have to do a “paper design”.