A low-power 10-bit 250-KSPS cyclic ADC with offset and mismatch correction

Abstract

A low power 10-bit 250-k sample per second (KSPS) cyclic analog to digital converter (ADC) is presented. The ADC's offset errors are successfully cancelled out through the proper choice of a capacitor switching sequence. The improved redundant signed digit algorithm used in the ADC can tolerate high levels of the comparator's offset errors and switched capacitor mismatch errors. With this structure, it has the advantages of simple circuit configuration, small chip area and low power dissipation. The cyclic ADC manufactured with the Chartered 0.35 μm 2P4M process shows a 58.5 dB signal to noise and distortion ratio and a 9.4 bit effective number of bits at a 250 KSPS sample rate. It dissipates 0.72 mW with a 3.3 V power supply and occupies dimensions of 0.42 × 0.68 mm2.