5th Order, Zero Error, Bessel, Switched Capacitor Lowpass Filter

The MAX281 is a 5th-order all-pole instrumentation lowpass filter with no DC error. The filter uses and external resistor and capacitor to isolate the integrated circuit form the DC signal path, thus providing DC accuracy.

The external resistor and capacitor together with the on-chip 4th-order switched capacitor filter form a 5th-order Bessel lowpass-filter. Bessel lowpass filters provide linear phase (constant group delay) response from DC to beyond the filter cutoff frequency, with some reduction in stopband attenuation.

The filter cutoff frequency is set by a clock which can be either internally generated or externally provided. The clock to cutoff frequency ration of 101 allows easy removal of clock ripple

MAX281A provides tighter specifications than the MAX281B for internal clock oscillator frequency and buffer amplifier offset voltage.

APPLICATIONS

* Anti-Aliasing Filters

* Data Loggers

* Digital Voltmeters

* Weigh Scales

* Strain Gauges

* Bessel Lowpass Filter with No DC Error

* Low Passband Noise

* DC to 20kHz Cutoff Frequency

* 5th-Order AII-Pole Bessel Response