A Wirelessly Powered Injection-Locked Oscillator with On-Chip Antennas in CMOS for IOT Sensor Node
Master of Science
In recent years, the Internet of Things (IoT) has emerged as the main technology trend. By connecting every physical object embedded with sensors and actuators, the IoT merges with the real physical world to the virtual Internet world. This new network opens up tremendous opportunities in all kinds of applications, ranging from health care to autonomous car design to the oil and gas industry. However, the IoT network also presents many challenges. One important challenge is power source. Regularly changing the batteries of billions of IoT devices seems impossible. Nor can we run with billions of cables to connect these devices. One promising solution is using wireless power. In the past few decades, we have benefited from progessive CMOS technology to shrink the size of the silicon chip. However, as for antenna, there is a fundamental trade off between size, efficiency, and frequency. For IoT systems, a lot of optimization should be done to aggressively shrink the wireless powered chips with on-chip antennas to millimeter size. To address these issues, this thesis presents the first batteryless mm-sized wirelessly powered injection-locked oscillator with on-chip antennas in 180nm SOI CMOS. The chip harvests electromagnetic radiation from a continuous-wave source in the X-band using the on-chip antenna. In addition, the chip is equipped with a broadband injection-locking oscillator that locks to the frequency of the input and produces a synchronized signal at the half frequency of the input. The locked signal is then radiated back by the on-chip dipole antenna. This architecture resolves the conventional self-interference issues in RFID sensors by separating the received and transmitted frequencies. In addition, the locking mechanism improves the phase-noise of the on-chip oscillator to -93dBc/Hz at 100Hz offset.
wireless power; energy harvesting; on-chip antenna; IOT; sensor node