Function description

Universal: Configurable as various low-pass, high-pass, low-pass, high-pass and band-pass filters. It uses the classic state variable-bandpass, bandstop analog architecture with an inverting amplifier and two simple design process integrators. The integrator includes an on-chip 1000pF precise frequency and Q: capacitor, trimmed to 0.5%. This structure solves one of the most difficult problems of active filters - including on-chip 1000pF ± 0.5% capacitor design to obtain close tolerance, low loss capacitors. The application's DOS-compatible filter design program allows for easy implementation of multiple filter types, such as test equipment Butterworth, Bessel, and Chebyshev. Fourth, non-commitment FET input op amps for communication equipment (same as another medical instrument III) can be used to form additional stages, or special filters such as band-stop filters and inverse Chebyshev filters for data acquisition systems . Monolithic replacement for UAF41
The classic topology of the UAF42 forms a time-continuous filter without the anomalies and switching noise associated with switched capacitor filter types.
The UAF42 is available in 14-pin plastic DIP and SOIC-16 surface mount packages and is specified for a temperature range of -25°C to +85°C.

application information
UAF42 is a monolithic implementation of the basic building elements of the most mature state-variable analog filter topology. This commonly used filter type is a second-order device that is pin-compatible with the popular UAF41. This section presents a complex conjugate analog filter with some improvements. The natural frequencies, wn and q of the pole pair determine the slew rate characteristic response of the UAF42 has increased to the cross section. The low pass transfer function shows 10V/ms compared to 1.6V/ms for the UAF41. Equation 1: The frequency 8226 ;q product of the UAF42 is improved and the useful natural frequency is expanded by 4 to 100kHz. (1) The FET input op amp on the UAF42 provides very low input bias current. The overall structure of the UAF42 reduces the cost of the high-pass transfer function and improves reliability. Formula 2:
The design program application report SBFA002 and the computer-aided design program equations make it easy to design and implement a wide variety of active filters. A DOS-compatible program guides you through (3) the design process and automatically calculates component values. By summing the low-pass and high-pass outputs, the band-stop response is obtained, resulting in the transmission low-pass, high-pass, band-pass, and band-stop functions as shown in Equation 4: (notch) filter. The program supports the three most commonly used all-pole filter types: Butterworth, Chebyshev, and Bessel. The less familiar (4) inverse Chebyshev filter is also supported, providing a smooth passband response with ripple on stop. The most common filter types are made up of one or one frequency band. More cascaded second-order parts. Each section is designed for wn and q according to filter type, each data entry, program automatic (Butterworth, Bessel, Chebyshev, etc.) and cutoff calculates and displays filter performance. this frequency. While tabular data can be discovered, iFeature allows a spreadsheet-like what-if design to design almost any filter design text that a design program can implement. For example, users can quickly identify and eliminate this tedious process. By trial and error, how many poles are needed to achieve the desired attenuation in the stopband. The second-order portion of the gain/phase diagram can be non-vertical and any response type can be viewed. (Fig. 1) or upside down (Fig. 2). The design formulas of these two basic structures are given for reference. The design program solves these equations, providing complete results, including component values.