Input offset voltage parameter of IC LT1990 is not matching with datasheet. we are getting 15mV to 300mV offset voltage for gain 10 configuration. please suggest how we can reduce offset voltage of IC. Find attached design configuration for details.
The configuration looks reasonable.
The offset of 15-300 mV may not be an offset. It may actually be swinging around that you don't see on a DC offset meter.
And I wonder whether the common modes are ok.
Is the input floating around, or solid? Yes, this part can handle large common mode.
But they drawing shows no indication of how the input common mode (the average voltage) is determined.
So reducing the offset would not be my engineering approach. It would be to make sure the use of the part is right (common mode is determined, not floating around) and also that the part is not wildly unstable for reasons we don't know yet (use a scope).