I'm trying to sense the current through a wire, and so far I decided to use a 1mOhm shunt resistor to convert it to voltage. As you see in the below circuit, the current source I1 sources 6A amplitude PWM current pulses(freq. is 1kHz). The idea is to adjust the current by the PWM coming from a uC.
But I also want to regulate this current and for that I need the uC to sense the current. So far I came up with the following circuit which is a LPF with gain:
Above the active LPF here mappes the PWM current to a 0 to 4V DC voltage which will go to one of the ADC of the microcontroller.
The opamp I use is a special amplifier with very low offset drift. In simulation only this opamp works the rest I tried all causes significant offset in simulation.
The LPF by the way has 20Hz cut off and designed by the filter design tool.
Eventhough this works in simulation, Im not happy with this interface. First of all, it is SMD and has many cascaded staged to solder.
So my question is:
1-) Is there an alternative easier way to sense this current here. Like a single DIP IC which translates the current to voltage with less soldering effort? Or any other single chip DIP LPF?
2-) How about instead of averaging current by a LPF, what alternative way could be use to send the actual current information as voltage to uC ADC? (I thought measuring the duty cycle but that didn't make sense because I already know the duty cycle which is coded to the uC)
I'm unable to solder SMD.
Edit2:Entire circuit(NPNs might not be needed):