Programmable 1-D rank filter of O(1) time complexity

An efficient architecture and circuit implementation for programmable rank filtering is presented. The circuit ranks a one-dimensional signal in an amount of time independent of the number of signal values and the rank number. The operation is based on one MIN and one MAX filter, and can be efficiently implemented using winner-take-all circuits of O(1) time complexity and O(n) hardware complexity. SPICE simulations and experimental results from a fabricated CMOS chip are included.