An ultra-low-power and mixed-mode event-driven face detection SoC for always-on mobile applications

A new face detection SoC integrating CIS array with low-power face detector on a single chip in analog-digital mixed-mode is proposed for ultra-low-power mobile device applications such as always-on user authentication. The proposed event-driven mixed-mode face detection SoC performs Viola-Jones face detection with not only analog face detection circuits but also digital vision processor. The analog face detection circuits enable 85% of workload to be skipped before A/D conversion and digital face detection processing, resulting in 39% power reduction. Implemented in 65nm CMOS technology, 11.09 mm
²
chip with 2.5V for CIS and 0.8V for digital vision processor consumes 24μW and 96μW at 1fps with non-face images and face images, respectively.