This paper proposes an Inter-Stage Gain Error (ISGE) calibration method devoted to correct the residue gain errors induced by the parasitic effects, non-ideal op-amp gain and capacitor mismatch, and also the mismatches for supply-derived reference voltages between two stages for Pipelined-SAR ADC. The calibration reuses the SAR ADC to estimate the overall inter-stage gain error and compensates it in the 2-stage DAC in 2 cycles, and it is implemented in a Pipelined-SAR which achieves 10b 470 MS/s in 65nm CMOS with the FoM of 31.5fJ/conv.-step by consuming only 6% of the total ADC area (0.049mm). © 2012 IEEE.