Adaptive thresholding for visual attention and tracking systems

A simple adaptive thresholding circuit for visual attention and tracking applications is presented. When used in visual attention systems or in tracking systems, the circuit allows "background" inhibition and false alarm reduction. A test chip with an eight-element adaptive thresholding circuit has been implemented in a standard 0.5-μm CMOS process and is operated via a 3.3-V supply in the saturation region. The circuit architecture is discussed, operation in saturation and subthreshold regions are explained, and measurements from a test chip are reported.