UAF42 is a universal active filter that can be configured for various low-pass, high-pass, and band-pass filters.
It uses a classic state-variable analog architecture with an inverting amplifier and two integrators.
The integrator includes an on-chip 1000pF capacitor trimmed to 0.5%.
A fourth useless FET input operational amplifier (same as the other three) can be used to form additional stages, or for special filters such as band stop and inverse Chebyshev.
Generally used in power system, sensor signal processing, transmitter and receiver, signal generator processing, etc.