Features and Overview
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User-programmable gain
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User-programmable corner frequency (from 20 Hz to 150 kHz), Notch frequency (for low and high filter pairs) and damping ratio with no external components
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Filter corner-frequency stability directly derived from clock accuracy
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Filter sampling rates up to 1.5 MHz
The ELPF4 User Module implements a general purpose four-pole low-pass filter with up to two pairs of elliptical zeroes at user selectable frequencies. The zeroes result in notches in the transfer function, intended to eliminate specific frequencies. Damping ratio are functions of the clock frequency and the ratios of the capacitor values calculated automatically based on the user parameters preset (Corner, Sample and Notch frequency, Gain, Filter type). Any of the classical all-pole filter configurations (Butterworth, Bessel, and Chebyshev) can be implemented. You can also select custom filter configuration, and enter values for complex poles. The corner frequency can be set very accurately or adjusted by controlling the sample rate clock. The filter output can drive the analog output bus.
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