What OP AMP should I choose?

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keltis98

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Hi! I'm making an analog circuit with some differential amplifiers and I wondering what could be the best OPAMP for that task.
As an input I have 2 current clamps that have 1 mV/A as an output. I will measure only a max of 20 A therefore I will have max 20 mVrms. I would like to amplify the signalin order to read it with an ADC.
What OPAMP do you think would be the best for that?
Schematic attached.

Thanks in advance!
Sam
1602189751115.png
 

Hi,

I'd go to an electronics distributor or Opamp manufacturer's internet site and use their Opamp selection guide...

Klaus
 
Apart from OP properties, I would check if the circuit topology can provide sufficient common mode rejection. If not, you may want to refer to dedicated instrumentation amplifiers.
 
I just reviewed your circuit.
It looks overly complicated ...
Maybe it works in simulation, I doubt it will work in reality.
There is a big "almost floating node"..it will catch up any noise around .... and may make the whole system unstable.

Klaus
 

The reason for generating sum and difference of the two inputs isn't clear. I'm just assuming that it serves a purpose.

The floating reference node mentioned by Klaus looks like the schematic error.
 

KlausST said:
I just reviewed your circuit.
It looks overly complicated ...
Maybe it works in simulation, I doubt it will work in reality.
There is a big "almost floating node"..it will catch up any noise around .... and may make the whole system unstable.

Klaus
Click to expand...
Thank you for your answer, the floating node you're talking about is the virtual GND I use to have negative voltage from the sinus signal.
I'll speak with my teacher tomorrow morning because he proposed me this circuit.

Thanks again,
Sam
 

To allow bipolar output, the reference node would be connnected to Vref/2 respectively Vcc/2. Please note, that the outputs are relative to reference node. Leaving it floating gives undefined output.
 

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