A new constant time analog rank order filter with O(n) complexity

ROF extracts the voltage magnitude by specifying the rank kth from a given set of inputs. A New and simple voltage-mode analog rank order filter architecture is presented. This paper we proposed a ROF which only needs a unit voltage as an input and selects the smallest value. Meanwhile, for multiple unit voltage by k, the proposed ROF easily selects their respective kth value. The overall hardware exhibits linear increase of complexity with the number of inputs O(n). Rank is easily programmable with voltage for all rank order values from Max. to Min. Moreover, bias current for charging output capacitor is fixed, unlike the previously reported circuits, this makes the proposed structure be constant with time. It can be observed in the simulation result that the slope of voltage rising is constant. In other words, the delay of reaching kth voltage value remains the same regardless of the number of input.