OPA340: offset voltage for R/C integral

Part Number:OPA340

Hello

I have a question regarding the offset voltage caused by the R/C integral.

I would like the measure a signal from the output from Rogowski Coil. I use a R/C integral after. R is 1000k ohm and C is 5.6nF. And I use a Non-invert input Op Amp circuit to amplify the signal. I use 1.5V as the middle voltage. But I found the offset in the output of the R/C is 1.51V. Additional 80mV appears. When I reduce the resistor value. The offset reduced. Who can tell me how the offset occurs and how to reduce it?

Thanks!(Please visit the site to view this file)