The Cross-Coupled Pair - Part I [A Circuit for All Seasons]

An elegant circuit is one that realizes a function efficiently. A beautiful circuit is one that stands the test of time. The cross-coupled pair (XCP) is such a topology: it has evolved for 95 years and adapted itself to various device technologies, supply voltages, and operation speeds. In this and future columns, we analyze this circuit?s properties and study its applications in both analog and digital design.