Energy-Efficient Low-Power Mm-Scale Wireless Communication System

Abstract

This dissertation focuses on low-power, energy-efficient RF wireless communication designs to be used within miniaturized millimeter-scale systems. There are several challenges to be overcome. First, the antennae within in the constrained dimensions of a miniaturized system have limited radiation efficiency and difficulty in matching because of their electrically small nature. Second, the battery capacity and driving ability are limited by the millimeter-scale size, which requires the radio system to be an energy-efficient and low-power design. Third, the high-power or large size off-chip components such as the high performance >1MHz crystal oscillator or >1mF super cap also challenge the size and power constraints. This dissertation analyzed these challenges and proposed a new circuit architecture and system design to solve them. Two prototypes of the proposed RF system were implemented for evaluation and verification. The first work is a 1.3uW, 2.7GHz back-scatter transceiver for an active, battery-powered, light-energy-harvesting mm-scale sensor with an integrated 2.1×4mm planar antenna. The fully stand-alone 1×2.1×4mm3 sensor node including radio chip, processor, antenna battery, and light harvester can communicate with the gateway at a distance of 3.5m. The second work is a 1.6mW narrow-band, PLL-less quasi-coherent 1.6mW RF transmitter. It employs a polar-coded differential (D)BPSK modulation, a self-optimizing flicker-noise reduced LO, and an automatic impedance matching PA with a 7×7×12mm co-designed antenna to improve transmission distance. The work in this dissertation shows the feasibility of low-power, mm-size, fully stand-alone systems in wireless communication, which can be applied in various areas of emerging IOT applications.