Although active filters are vital in modern electronics, their design and verification can be tedious and time consuming. To aid in the design of active filters, Burr-Brown provides a series of FilterPro™ computer-aided design programs. Using the FILTER42 program and the UAF42 it is easy to design and implement all kinds of active filters. The UAF42 is a monolithic IC which contains the op amps, matched resistors, and precision capacitors needed for a state-variable filter pole-pair. A fourth, uncommitted precision op amp is also included on the die.