Charge injection cancellation in sample-data-comparators using programmable staggering of zeroing signals

Abstract

Comparator offsets resulting from charge injection of MOS switches vary over temperature, supply voltage, and process. These variations lead to difficulties in achieving optimum offset voltages. In a three-stage comparator design with current programmable delay times between autozero signals, optimum offset voltages are achieved over a wide range of operating conditions. By forcing a constant voltage swing on the feedback switches, channel charge injection dependence on effective threshold voltage levels leads to uncompensated offset errors.<>