A Real-Time Current-Mode CMOS Analog Median Filtering Cell for System-on-Chip Applications

Signal processing circuits are very useful elements in fuzzy logic, artificial neural network, and image application. In image processing, median filter is adopted to remove pulse noise. In the paper, a real-time CMOS analog median circuit is proposed. Based on current-mirror, current comparison, and some digital logics, a new analog median filter with high-speed low chip area is achieved. By using TSMC 0.35 μm CMOS technology, the median filter provides a 0.4-μA discriminability and well tracked the median value among input currents. In addition, the median filter cell can be expanded to have signal level 'sort' capability.