Noise reduction by filtering is the most commonly usedmethod for improving signal-to-noise ratio. The increase insettling time, however, can be a serious disadvantage insome applications such as high-speed data acquisition systems.The nonlinear filter described here is a simple way toget a four-to-one improvement in settling time as comparedto a conventional filter.To understand the circuit, first consider the dynamics of asingle-pole RC filter (Figure 1). Filtering reduces broadbandor “white” noise by the square root of the bandwidth reductionas shown by the following calculation: