A Digital-Calibration Technique for Redundant Radix-4 Pipelined Analog-to-Digital Converters

This paper describes a digital-calibration technique, which corrects gain errors due to capacitor mismatch and offset errors due to charge injection in redundant radix-4 pipelined analog-to-digital converters (ADCs). The error coefficients are directly measured using an integral nonlinearity (INL) plot. The proposed method simplifies the error-measurement process and removes on-chip measurement circuits in the ADC. Computer simulations show that the maximum INL of 15 LSB in an uncalibrated 15-bit ADC is reduced to less than 0.3 LSB using the digital calibration.