A Single-Chip Image Sensor Node With Energy Harvesting From a CMOS Pixel Array

Abstract

This paper presents a single-chip image sensor node with energy harvesting from the pixel array. The design includes a $128 \times 96$ pixel array that can be reconfigured to form an on-chip photovoltaic cell to harvest energy. An on-chip power management unit harvests energy from the pixel array, and delivers multiple regulated output voltage domains to power the sensor, image processor, and memory. The image processor is a low-overhead moving object detection unit to reduce the volume of transmitted data. The proposed sensor node is implemented on a single die in 130-nm technology. The pixel array demonstrates the peak harvested power of $2.1\mu \text{W}$ . The power dissipation of sensor is reduced by utilizing low-power circuit techniques, including block-level pipelining, power gating, and low-voltage memory. The system can be self-powered to process a frame at every 7 s. We discuss design approaches for improving the self-power performance. The noise characteristic of the reconfigurable sensor is analyzed, and the need for noise-robust moving object detection is evaluated for better image quality and improved self-power performance.