A 4.6μm, 512×512, Ultra-Low Power Stacked Digital Pixel Sensor with Triple Quantization and 127dB Dynamic Range

We present a global shutter (GS), digital pixel sensor (DPS) that leverages stacked CMOS image sensor (CIS) technology to meet the ultra-low power, ultra-wide dynamic range (DR) requirements for battery-powered, always-on mobile computer vision (CV) applications. The DPS pixel is partitioned between two silicon layers via pixel-level connections, has an in-pixel ADC, 10-bit SRAM, and 4.6µm pitch. We introduce a triple quantization (3Q) scheme that combines a time-to-saturation (TTS) quantization mode and two linear ADC modes within a single exposure to achieve 127dB intra-scene DR. The sensor has a 512×512 effective resolution and consumes 5.3mW in 3Q operation at 30fps.