Dual output comparator for operating over a wide common mode range

Abstract

Data and strobe comparators are provided wherein each comparator includes a wide-swing bias circuit, an input stage, a current bias circuit, a load circuit, an output buffer and a clamp circuit. The wide-swing bias circuit, input stage, current bias circuit, load circuit, and a clamp circuit comprise a well-controlled preamplifier circuit. The input stage includes low-threshold transistors that receive differential inputs. The transistors form a single stage input. The low-threshold transistors turn on at several hundred millivolts, and from an operational perspective, almost immediately. The well-controlled aspect of preamplifier is achieved since all the transistors are made from the same semiconductor manufacturing process and have their physical dimensions precisely matched. An output buffer is connected to the preamplifier. Such a buffer is used for both data and strobe reception. The buffer includes a differential-to-single-ended converter that includes low-threshold transistors. The buffer can be disabled when clocked data is not being received.