This book covers several aspects of the operational amplifier and includes theoretical explanations with simplified expressions and derivations. The book is designed to serve as a textbook for courses offered to undergraduate and postgraduate students enrolled in electronics and communication engineering. The topics included are DC amplifier, AC/DC analysis of DC amplifier, relevant derivations, a block diagram of the operational amplifier, positive and negative feedbacks, amplitude modulator, current to voltage and voltage to current converters, DAC and ADC, integrator,...