The design and implementation of three analog median filter topologies, whose transistors operate in the deep weak-inversion region, is described. The first topology is a differential pairs array, in which drain currents are driven into two nodes in a differential fashion, while the second topology is based on a wide range OTA, which is used to maximize the dynamic range. Finally, the third topology uses three range-extended OTAs. The proposed weak-inversion filters were designed and fabricated in ON Semiconductor 0.5 µm technology through MOSIS. Experimental results of three-input fabricated prototypes for all three topologies are shown, with power consumptions of 90 nW in the first case, and 270 nW in the other two cases. A dual power supply ±1.5 Volts was used.