High frequency signal comparator for sha-less analog-to-digital converters

Abstract

A high frequency input signal comparator for optimizing group delay, reducing input frequency dependent offset and an offset auto-zeroing latch core are described. The comparator may include an isolation switch stage, and a latch core. The isolation switch stage may isolate latch core depending upon a control signal, thereby reducing input frequency dependent offset. The latch core may include a pair of inverters cross coupled via an impedance to one another. The latch core may include latch switches selected to attain a certain gain across the individual inverters comprising the latch core while resetting the latch core. The gain across the individual inverters during the acquire/reset phase may bootstrap the coupling impedances, thereby reducing loading and group delay at the input of the latch core. The coupling impedances may be designed to minimize or auto-zero statistical offset, thereby minimize input referred offset.