RAIL-TO-RAIL COMPARATOR WITH BUILT-IN CONSTANT HYSTERESIS

摘要

A comparator has an input stage having (i) resistor-coupled super source-follower circuits that convert differential input voltages into differential currents and (ii) hysteresis current-injection circuits that inject hysteresis currents into the differential currents. An output stage processes the differential currents to control the comparator output. Common-mode (CM) detection circuits inhibit some of the differential currents from reaching the output stage if the CM voltage is too close to a voltage rail of the comparator. The comparator is able to operate at CM voltages over the entire rail-to-rail range with constant hysteresis voltage.

主权项

1. A comparator, comprising:
an input stage comprising resistor-coupled source-follower circuitry that converts a differential input voltage into differential current independent of an operating region of transistors used to implement the source-follow circuitry; hysteresis current-injection circuitry that injects hysteresis current into the differential current generated in the input stage to add hysteresis voltage to operations of the comparator, wherein the hysteresis voltage is independent of the operating region of the transistors used to implement the source-follower circuitry; and an output stage that processes the differential current provided by the input stage to control an output of the comparator.