Texas Instruments UAF42

The UAF42 is a universal active filter which can be configured for a wide range of low-pass, high-pass, and band-pass filters. It uses a classical state-variable analog architecture with an inverting amplifier and two integrators. The integrators include on-chip 1000pF capacitors trimmed to 0.5%. This solves one of the most difficult problems of active filter designobtaining tight tolerance, low-loss capacitors.A DOS-compatible filter design program allows easy implementation of many filter types such as Butterworth, Bessel, and Chebyshev. A fourth, uncommitted FET-input op amp (identical to the other three) can be used to form additional stages, or for special filters such as band-reject and Inverse Chebyshev.The classical topology of the UAF42 forms a time-continuous filter, free from the anomalies and switching noise associated with switched-capacitor filter types.The UAF42 is available in 14-pin plastic DIP and ceramic packages, and SOL-16 surface-mount packages, specified for the -25°C to +85°C temperature range.