A Piecewise Multi-Correlation Based Digital Background Calibration Scheme for Pipelined ADCs

This paper proposes a digital background calibration scheme for the compensation of the linear and the third-order nonlinear gain errors of the residue amplifier (RA) in pipelined ADCs. The proposed calibration method, called the piecewise multi-correlation estimation (PMCE) technique, injects two pseudo-random number (PN) sequences within two adjacent dither windows to extract gain coefficients. This method transforms the estimation of nonlinear gains into the estimation of two linear gains, thus achieving rapid convergence. The proposed calibration scheme does not result in the output swing degradation of the multiplying DAC (MDAC) due to dither injection. The required modification to analog circuits involves only three additional comparators and a capacitor for dither injection. Monte Carlo simulation results of a 14-bit 1.3GS/s pipelined ADC show that the average SFDR of the ADC is improved from 59.61 dB to 91.11 dB.