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

Internet of Things (IoT) applications are being scaled to increasingly smaller sizes, introducing a need for low-power, energy-efficient RF wireless communication designs within miniaturized millimeter-scale systems. There are several challenges to be overcome. First, the antennae 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 several new circuit architecture and system designs to solve them. Two prototypes of the proposed RF system were implemented for evaluation and verification. The first work is a 1.3µW back-scatter transceiver for an active, battery-powered, light-energy-harvesting 1×2.1×4 mm sensor with an integrated planar antenna, which improves the uplink distance while achieving ultra-low power consumption and exploiting the coherence of dual-side bands to improve interference rejection. The second work is a 1.5mW narrow-band, PLL-less quasi-coherent 1.5mW 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 7×7×12 mm codesigned antenna to improve transmission distance.

Chair: Professor David Blaauw