In its early chapters this book develops a unified approach for dealing with nonlinear semiconductor circuits which are used in conjunction with selective band-pass filters. With these concepts as the fundamental tools, the subsequent chapters explore the basics of sinusoidal oscillators, mixing circuits, power amplifiers, amplitude modulators and demodulators, and frequency modulators and demodulators. Much of the material in the later chapters is unique. In particular, the chapters dealing with frequency modulation and demodulation develop the functional form of almost all existing modulation circuits from a few basic theoretical concepts; such a unified treatment does not exist anywhere else.