Predictive comparators with adaptive control

Abstract

A linear predictor and adaptive control loop are added to a conventional comparator to greatly reduce the delay. A linear predictor feeds an estimated future signal to the comparator to compensate for the comparator's internal delay. On a cycle-by-cycle basis, an adaptive controller adjusts the comparator's bias current to null the error. Emphasis is placed on low power consumption, including the development of a linear predictor with no static power consumption. Improvements of two orders of magnitude in power-delay product are demonstrated. The adaptive comparator is ideally suited for applications such as synchronous rectification but will also find broad applicability anywhere an asynchronous comparator is required, such as sensor interfaces, oscilloscope triggers, and some types of analog-digital converters.