The ALD1721E/ALD1721 is a monolithic rail-to-rail precision CMOS operational amplifier with integrated user programmable EPAD (Electrically Programmable Analog Device) based offset voltage adjustment. The ALD1721E/ALD1721 operational amplifier is a direct replacement of the ALD1701 operational amplifier, with the added feature of user-programmable offset voltage trimming resulting in significantly enhanced total system performance and user flexibility. EPAD technology is an exclusive ALD design which has been refined for analog applications where precision voltage trimming is necessary to achieve a desired performance. It utilizes CMOS FETs as in-circuit elements for trimming of offset voltage bias characteristics with the aid of a personal computer under software control. Once programmed, the set parameters are stored indefinitely within the device even after power-down. EPAD offers the circuit designer a convenient and cost-effective trimming solution for achieving the very highest amplifier/system performance.