Millimeter-Scale and Energy-Efficient RF Wireless System

Abstract:

This dissertation focuses on energy-efficient RF wireless system with millimeter-scale dimension, expanding the potential use cases of millimeter-scale computing devices. It is challenging to develop RF wireless system in such constrained space. First, millimeter-sized antenna is electrically-small, resulting in low antenna efficiency. Secondly, energy source is very limited due to small battery or energy harvester. Lastly, it is desired to eliminate as many as off-chip devices to further reduce system dimension. In this dissertation, the challenges are explored and analyzed, and new methods are proposed to solve those issues.

Three prototype RF systems implemented for demonstration and verification. First prototype is a 10 mm3 inductive-coupled radio system that could be implanted through syringe, aimed for healthcare applications with constrained space. Second prototype is a 3x3x3 mm3 far-field 915MHz radio system with 20-meter NLOS range in indoor environment. Third prototype is a low-power BLE transmitter using 3.5×3.5 mm2 planar loop antenna, enabling millimeter-scale sensors to connect with ubiquitous IoT BLE-compliant devices.

The work presented in this dissertation improves use cases of millimeter-scale computers by presenting new methods for improving energy efficiency of wireless and shrinking radio system dimension. The impact is significant in the age of IoT when everything will be connected in daily life.