Sharp cutoff filters with monotonic passband response

Rational functions approximately monotonic in the passband, with one pair of zeros on the imaginary axis, have been compared with allpole functions, monotonic in the passband, for the lowpass filter applications. It is shown that usage of the zeros as a parameter can accomplish a trade between minimum stopband attenuation and sharpness of the cutoff characteristic. The paper concludes with a detailed example showing the efficiency of the proposed technique.