Low-pass filters for signal averaging

Detailed comparison of the settling time-noise bandwidth products of 31 types of low-pass filters demonstrates that the settling time-noise bandwidth product is the figure of merit for such filters when the goal is averaging. Common filters such as Butterworth, elliptic, and Chebyshev are found to be unusable for such purposes while others, such as Bessel filters, offer only moderate figures of merit. The best reported analog low-pass filter differs from ideality by only about 11%. The optimum analog low-pass filter, having continuous, rational transfer function, is unknown.