This volume covers four major fundamental types of analogue filters - passive, op amp-RC, switched-capacitor, and operational transconductance amplifier-capacitor (OTA-C). (The last of these types is the major addition in the second edition). The emphasis is on the fundamental principles and theory of analogue filters. It is targeted toward readers in telecommunications, signal processing, electronics, controls, instrumentation, bioengineering, and so forth. It introduces the reader to the elegant theory in the development of analogue filters. Although some of the mechanical steps for generating filters are covered, the book stresses the mathematical bases and the scholastic ingenuity of analogue filter theory. It should be helpful to nonspecialist electrical engineers to gain a background perspective and some basic insight to the development of real-time filters. In many modern advances in signal processing, their concepts and procedures have close links to analogue filters. The material in this book should provide engineers with a better perspective and more penetrating appreciation of many modern signal-processing techniques.