ANALOG AMPLIFIERS - CLASSIFICATION AND GENERALIZATION

Amplifiers with high open-loop gain (operational amplifiers) are frequ ently encountered in analog signal processing circuits, since the appl ication of negative feedback enables numerous transfer functions to be implemented. The designer wanting to select an operational amplifier for a given application is met with a vast range of devices, with diff erent architectures optimized for particular system requirements. This range seems to be ever expanding, with ''novel'' amplifier topologies offering enhanced performance over more conventional devices, This pa per presents an overview of amplifier theory, and shows that many nove l amplifier architectures are simply implementations of earlier theori es which have been made possible by advances in process technology. Th e analysis also shows that many ideas such as fixed gain bandwidth pro duct are not inherent to negative feedback amplifier circuits, but res ult from the choice of amplifier architecture within a particular appl ication.