Tool/software:
I intend to measure the difference in voltage using the INA122 and generate an output with an offset of 1.425V running on a +2.85V supply.
With no input or 0V between J7 and J8, the output of the IA is 1.426V
With a voltage input of 20V(J8-J7), the voltage output at the IA is 2.344V
With a negative input of 20V(J8-J7), the voltage output of the IA is 0.478V
Checking the difference between the positive and negative input with reference to the output when there is 0V applied, there is a 30mV difference.
Hence, there seems to be a non-linearity when measuring a positive and negative input voltage.
The circuit diagram and the table shows the details of the above mentioned.
I would hence like to seek any advice on the possible issue and how the issue can be resolved.
INA 122 | ||||||
VIN | + | - | REF | CV+OUT | ||
J8 - J7 | X2 P3 | X2 P2 | X2 P5 | X2 P6 | ||
-20.05 | -0.0618 | 0.0618 | 1.425 | 0.478 | ||
0 | 0.0000 | 0.0000 | 1.425 | 1.426 | 0.948 | |
20.05 | 0.0618 | -0.0618 | 1.425 | 2.344 | 0.918 |