operational amplifier, amplifier whose output voltage is proportional to the negative of its input voltage and that boosts the amplitude of an input signal many times, i.e., has a very high gain. It is usually connected so that part of the output is fed back to the input. Operational amplifiers were originally developed to be used in synthesizing mathematical operations in analog computers, hence their name. Because of recent advances in semiconductor technology, they have become available as integrated circuits. They are widely used when a closely controlled amount of gain or some form of signal processing is necessary in an electronic system.