Architecture and design of an RF receiver front-end and transmitter for wireless sensor networks, healthcare and smart energy systems

Abstract

Wireless communication networks have in no small part affected our everyday lives. They revolutionized the way humans interact with each other and with the world around them. The ubiquitous use of the available spectrum is turning our world into a connected wireless medium. As a result, wireless communication networks are poised to play a greater role in solving some of our key future challenges in energy, healthcare and agriculture. We are at the cusp of having the technology to connect everything humans interact with using wireless networks. The internet of everything is almost a reality; it is our profession’s next frontier. At the heart of this challenge is the need for ubiquitous wireless communications utilizing RF transceivers which consume the lowest possible energy. The thesis focuses on the architecture, design, implementation and evaluation of an RF transmitter and receiver front-end which are part of the foundations of a commercial RF system on a chip. The use of a number of digitally-assisted analog and RF techniques enables a fully integrated, low energy, low cost and high performance RF transmitter and receiver. The thesis addresses four key challenges in low energy RF transceivers: 1. The design of a low energy zero-IF receiver using a fast digitally-assisted offset cancellation loop. The receiver has the best-in-class RF blocking performance with 20dB better adjacent channel rejection than the best low-IF architecture in the prior art. 2. The design of a low power RF mixer using a novel LO circuit which consumes one-fourth of the power of traditional LO circuits. 3. The design of a wide-bandwidth low energy RF transmitter using a digitally-assisted preemphasis technique to extend the analog bandwidth of the frequency synthesizer by a factor of four. This enables RF modulation of FSK signals up to 2Mbps. The RF transmitter has 60% smaller die area, 50% less power consumption and its calibration system consumes 90% less energy when compared to the best prior art. 4. The design of a novel digitally-assisted calibration system to maintain the accuracy of the digital modulation at the output of the RF transmitter in the presence of process, temperature and supply variations.