This textbook comprehensively presents different types of analog function circuits and outlines the function circuit types implemented with lowpass filters, peak detectors, and sample and hold circuits. The text analyzes the complete architecture of a function circuit, identifies the applications of op-amps for performing a function circuit, and explores new ways of deriving function circuits using a sawtooth wave generator and a triangular wave generator. It covers important topics including waveform generators, analog dividers, time division multipliers-cum-dividers (MCDs), peak responding MCDs, vector magnitude circuits, multifunction converters, and phase sensitive detector circuits. The textbook will serve as an ideal study material for senior undergraduate and graduate students in the fields of electrical, electronics, and communications engineering. The textbook is accompanied by teaching resources, including a solutions manual for instructors.