A HIGH-RESOLUTION MULTIBIT-SIGMA-DELTA ADC WITH DIGITAL CORRECTION AND RELAXED AMPLIFIER REQUIREMENTS

In this paper a second-order multibit SIGMADELTA A/D converter with a 4-b internal quantizer is described. It uses a simple and fast digital correction scheme. A correlated-double-sampling (CDS) fully different ial integrator was used, in which the op amp needed only a low slew ra te and moderate bandwidth for a sampling rate of 5.25 MHz. A second-or der modulator was fabricated in the standard MOSIS p-well 2-mum CMOS p rocess. The excellent measured linearity and high S/(N + D) ratio (95 dB with an oversampling ratio of only 128) of the corrected converter verified the practical advantages of the proposed architecture.