UAF42

® APPLICATION BULLETIN Mailing Address: PO Box 11400 Tucson, AZ 85734 Street Address: 6730 S. Tucson Blvd. Tucson, AZ 85706 Tel: (602) 746-1111 Twx: 910-952-111 Telex: 066-6491 FAX (602) 889-1510 Immediate Product Info: (800) 548-6132 FILTER DESIGN PROGRAM FOR THE UAF42 UNIVERSAL ACTIVE FILTER By Johnnie Molina and R. Mark Stitt (602) 746-7592 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. Filters implemented with the UAF42 are time-continuous, free from the switching noise and aliasing problems of switched-capacitor filters. Other advantages of the statevariable topology include low sensitivity of filter parameters to external component values and simultaneous low-pass, high-pass, and band-pass outputs. Simple two-pole filters can be made with a UAF42 and two external resistors—see Figure 1. The DOS-compatible program guides you through the design process and automatically calculates component values. Low-pass, high-pass, band-pass, and band-reject (or notch...