Precise and High-Speed Technique of Digital Calibration for Column-Parallel Two-Stage Cyclic ADC Suitable for 33-Mpixel 120-fps CMOS Image Sensor

Abstract

A digital calibration technique for a column-parallel two-stage single-ended cyclic ADC needs to accurately determine error coefficients that define the quantity of errors caused in the ADC. However, the error coefficients have so far been determined on the basis of estimation from the design parameters of the ADC. Therefore, we proposed a new ADC operation and signal processing scheme to determine them accurately and dynamically by measuring the ADC output code including the errors and verified its effectiveness for precise and high-speed technique of digital calibration by performing a preliminary experiment using the ADC test circuit.