A 0.8 V Multimode Vision Sensor for Motion and Saliency Detection With Ping-Pong PWM Pixel

This article presents a low-power, high-speed smart vision sensor for motion detection (MD) that realizes in-pixel frame-difference (FD) operation using a global shutter mechanism. A ping-pong pulse-width-modulation (PWM) pixel is proposed to achieve the consecutive event frame report with a balanced signal transfer function of successive FD operations. Three operating modes were implemented for varied application scenarios, such as image capture (IC) mode to capture a raw image, FD mode for MD, and saliency detection (SD) mode for low-resolution sub-block event counting. A 0.8 V 64 $\times $ 64 vision sensor prototype was fabricated and verified in TSMC 0.18- $\mu \text{m}$ standard CMOS technology. In IC mode, it consumed 71.2 $\mu \text{W}$ @360fps with an achieved iFoM of 48.3 $\text {pJ/pixel}\cdot \text {frame}$ . In FD mode, it consumed 74.4 $\mu \text{W}$ @510fps with full-resolution (64 $\times $ 64) event reporting and achieved iFoMs of 35.6 $\text {pJ/pixel}\cdot \text {frame}$ . In SD mode, it consumed 121.6 $\mu \text{W}$ @890fps with block-level (8 $\times $ 8) saliency reporting and achieved iFoMs of 2.1 $\text {nJ/block}\cdot \text {frame}$ .