An analog circuit technique for finding the median

A novel analog technique for finding the median of an odd number of inputs is presented. It is shown that simple analog circuits can be used to find the median. Their compactness allows their use in parallel systems, such as pixel plane processing, yielding enormously effective computation rates. In addition, their analog nature allows them to be easily incorporated into systems where digital median filters are impractical, such as high-speed communications equipment. More generally, the technique described can be used to implement a large class of nonlinear filters based on rank order. A three-input median circuit, implemented in a 2-μm CMOS process, demonstrates the effectiveness of the technique