Sub-Micron Binary HyperPixel Sensor Circuit: In-Pixel Binarization with Variable Thresholding

Image binarization holds significant importance in computer vision, document analysis, and various AI applications. In a multitude of such applications, the acquisition and processing of full-value grayscale images are deemed unnecessary, as binary images are often sufficient for the intended tasks. We design and simulate a simple, compact, high-speed, low-power, and low-area binary pixel sensor (BPS) featuring pixel-level processing (i.e. each pixel has its own binarization module). Our BPS integrates a variable thresholding feature, ensuring adaptability to diverse lighting conditions. Due to our concise design, we achieve a sub-micron pixel pitch (~0.65 µm) through a stacking configuration, where the photodiode resides in the upper layer and the remaining circuitry occupies a 0.35×0.504 µ m
²
in the lower layer. Notably, our BPS boasts a remarkably low power delay product of 0.152 fJ.