Split ADC Based Fully Deterministic Multistage Calibration for High Speed Pipeline ADCs

A fully deterministic digital background calibration for pipeline ADCs is presented. The proposed approach is based on split ADC concept to give the shortest background calibration time with high accuracy. A slope mismatch averaging technique is employed in a multistage calibration scheme to deterministically detect the circuit errors without any iterative operations or feedback loops, which render it fast and accurate. Analysis and behavioral simulations for the developed multistage calibration demonstrate the efficiency of this technique and its merit over the LMS-based techniques. Practical considerations have been considered and the proposed calibration has been applied on a 200 MS/s 40 nm CMOS split pipeline ADC to correct for the capacitor mismatch and the amplifier finite gain. The post-layout simulation results show a very fast calibration cycle, where the ADC achieves more than 11 ENOB in less than 1600 clock cycles.