Miniaturized Low-Power and Energy-Efficient RF Wireless Communication and Sensing Systems

Abstract:

There are several challenges in miniaturizing RF wireless systems with an integrated antenna into a centimeter or even millimeter-scale. First, millimeter-sized antennae in radio frequency are electrically-small, resulting in low radiation efficiency as well as difficulties to match the impedance. Second, the energy source is limited due to a small form factor battery. Third, bulky off-chip components such as high frequency crystal unavailable due to reduced system dimension. In this dissertation, these challenges are analyzed and tackled by proposing new circuit architecture and system design techniques as well as new algorithms.

Three prototypes of the proposed systems were implemented for evaluation and verification. The first one is a crystal-less 3x3x3 mm 915MHz asymmetric radio system optimized for indoor NLOS communication. The second work is a fully integrated 4x4x4 mm radio with newly proposed carrier frequency interlocking IF transceiver architecture, enabling a symmetric sensor-to-sensor communication. Last, an energy-efficient and rapidly deployable RF localization system with crystal-less ASIC tag was proposed together with a neural network time-of-flight estimation algorithm. The prototype systems presented in this dissertation prove the feasibility of low-power and energy-efficient designs to expand applications of wireless sensor nodes and improve the connectivity of devices in the IoT era.