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AD620AN opamp problem

Category: Hardware


I want to read sensors with AD620AN. I am using wheatstone bridge.

However, opamp doesnt give a reasonable output. Therefore, I build a test circuit. I attached the screenshot of my circuit. Is this circuit correct for testing the opamp?

I am using LTSPICE and SPICE file that Analog Devices provided. LTSPICE output seems correct. However, when i build this testing circuit, it gives me 2V output.

[edited by: electrosurfer at 12:56 PM (GMT -4) on 25 Mar 2023]
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  • Hello electrosurfer,

    with the given parameters, your circuit violates the allowed input voltage range on all inputs. The amplifier will not run in spec, and so it cannot guarantue its intended parameters (like accuracy).

    Maybe the output comes nevertheless close to the correct value - but it's not guarantued. I cannot recognize, how accurate the datapoints in your simulation are and I cannot judge, what accuracy you require. But if you want a reliable and accurate circuit, you have to run your amplifier in the specified range.

    For the given circuit this would be easiest achieved with a bipolar supply (e.g. +10V on +Vs and -10V on -Vs).

    best regards