CMOS Comparators

Abstract

This chapter first presents an overview of CMOS voltage comparator architectures and circuits. Starting from the identification of the comparator behavior, Section 2 introduces several comparator architectures and circuits. Then, Section 3 assumes these topologies, characterizes high-level attributes, such as static gain, unitary time constant, etc., and analyzes the trade-off for each architecture. Such analysis provides a basis for comparison among architectures. These previous sections of the chapter neglect the influence of circuit dissymmetries. Dissymmetries are covered in Section 4; and new comparator topologies are presented to overcome the offset caused by dissymmetries. Related high-level trade-offs for these topologies are also studied in this section.