Microprocessor Programmable Universal Active Filters

The MAX260/MAX261/MAX262 CMOS dual second-order universal switched-capacitor active filters allow microprocessor control of precise filter functions. No external components are required for a variety of bandpass, lowpass, highpass, notch, and allpass configurations. Each device contains two second-order filter sections that place center frequency, Q, and filter operating mode under programmed control.

An input clock, along with a 6-bit f0 program input, determine the filter's center or corner frequency without affecting other filter parameters. The filter Q is also programmed independently. Separate clock inputs for each filter section operate with either a crystal, RC network, or external clock generator.

The MAX260 has offset and DC specifications superior to the MAX261 and MAX262 and a center frequency (f0) range of 7.5kHz. The MAX261 handles center frequencies to 57kHz, while the MAX262 extends the center frequency range to 140kHz by employing lower clock-to-f0 ratios. All devices are available in 24-pin DIP and small outline packages in commercial, extended, and military temperature ranges.

Applications

* µP-Tuned Filters * Adaptive Filters * Anti-Aliasing Filters * Digital Signal Processing (DSP) * Phase-Locked Loops (PLLs) * Signal Analysis

* Filter Design Software Available

* Microprocessor Interface

* 64-Step Center Frequency Control

* 128-Step Q Control

* Independent Q and f0 Programming

* Guaranteed Clock to f0 Ratio-1% (A grade)

* 75kHz f0 Range (MAX262)

* Single +5V and ±5V Operation