The role of the operational amplifier is in the actual circuit, usually combined with the feedback network to form a functional module, it is a kind of amplifier with a special coupling circuit and feedback, the output signal can be the input signal plus, minus or differential, integral and other mathematical operations results. It was first used in analog computers to perform mathematical operations,
Purpose; Widely used in the electronics industry, access to appropriate feedback networks, can be used as precision AC and DC amplifiers, active filters, oscillators and voltage comparators.