Background comparator offset calibration technique for flash analog-to-digital converters

Abstract

A background-calibrated comparator and a background-calibrated flash analog-to-digital converter are disclosed for using in mixed-signal integrated circuit design in particular on the high-speed analog-to-digital converter circuit. Without affecting the operation of the comparator, the disclosure is directed at reducing the unpredictable input offset voltage originated from the variation of process parameters and environmental factors. The background-calibrated comparator includes a random chopping comparator, a calibration processor, and a random sequence generator. The background-calibrated flash analog-to-digital converter (ADC) includes a background-calibrated comparator array together with a reference voltage generator, a thermometer code edge detector, and a set of digital encoders.