SBIR Phase I: Polar Transmitter for Ultra High Frequency Radio Identification Readers

The broader impact/commercial potential of this project is of such scope and diversity it can be difficult to capture. Over the coming decades passive UHF RFID will become a pervasive technology, not just in industrial, manufacturing, commercial, and retail operations but in the everyday lives of ordinary people. As passive UHF RFID makes its way into homes and appliances to help automate and simplify peoples' lives, the Gen2 readers must simultaneously have excellent dense reader performance and be small, inexpensive, and low power. The impact of this project includes a deeper understanding of polar transmitter application in UHF radios, in particular the achievable efficiency, linearity, and spectral purity in a pure switch mode envelope amplifier with no linear assistance. By focusing on GaN devices for all class-D envelope switching and class-E RF switching this project may be used as a step toward a true single chip, high output power UHF RFID reader using GaN-on-Si integrated circuit techniques. Such a low power, high performance reader chip would be an enabling component needed for the ubiquitous deployment of passive UHF RFID in the IoT. This Small Business Innovation Research (SBIR) Phase I project focuses on improving the power efficiency of the radio frequency power amplifier (RFPA) for ultra-high frequency (UHF) radio frequency identification (RFID) readers. In particular, the passive UHF RFID protocol known as ?Gen2? constitutes a substantial percentage of the Internet of Things (IoT), since most of the network?s endpoints do not have radio capabilities and will rely on Gen2 tags to be part of the network. A pervasive deployment of Gen2 infrastructure in retail, manufacturing, and distribution centers may require hundreds of readers in a single facility. Current technology requires expensive, bulky, power hungry RFID readers. The objective of the research is to develop a proof of concept for a new polar transmitter demonstrating nearly 85% reduction in the dissipated heat of the reader RFPA. The new RFPA architecture will employ a novel modulation format with continuously differentiable amplitude and phase signals enabling a pure switch mode polar RFPA while maintaining full time and frequency domain Gen2 dense reader compliance. The anticipated results are efficiency, linearity, and spurious noise performance tradeoffs given design parameters of the class D switch mode envelope amplifier and class E switch mode polar RFPA output stage.