Analog VLSI circuits for manufacturing inspection

We present three types of analog VLSI circuits that can be used in manufacturing inspection systems. The first set of circuits performs an adaptive threshold of an input image. The second circuit uses morphological operations with programmable structuring elements to detect oriented edges. Both of these circuits can be used as high speed preprocessors for visual inspection of manufacturing processes. The third circuit performs a computation necessary for selective attention in visual processing. This circuit is a component of a larger system that will facilitate a serial/parallel processing scheme in order to increase the speed of processing in machine vision tasks. All circuits presented use focal-plane processing to achieve their massively parallel architectures. For each design, the processing pixels contain vertical bipolar phototransistors to accommodate parallel optical inputs. All circuits have been fabricated using a standard 2.0 μm digital CMOS process. Data for each of these circuits is presented.