Introduction of Wireless Power Transfer
Wireless power transfer (WPT) for a broad range of applications is projected to have an exponential growth, with an enormous number of new devices and products to be enabled by this powerful technology. In this chapter, the background and motivations of W
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Introduction of Wireless Power Transfer
Abstract Wireless power transfer (WPT) for a broad range of applications is projected to have an exponential growth, with an enormous number of new devices and products to be enabled by this powerful technology. In this chapter, the background and motivations of WPT are introduced first. Then high-level considerations on WPT such as operation frequencies, WPT regulations and WPT standards are reviewed and summarized. In addition, design perspectives on the WPT circuits and systems are also examined. Finally, we present the organization of this book and provide some reading guidelines. Keywords Wireless power transfer • Inductive coupling • Wireless charging • Near field • Far field • Ultrasound • Optimum coupling distance
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Motivations
Wireless power transfer (WPT) has a wide range of applications including (arranged from low to high power levels) radio frequency identification (RFID), internet-of-things (IoT), implantable medical devices (IMDs), real-time wireless power for non-contact memory devices and wafer-level testing, and also wireless chargers for portable/wearable devices and electric vehicles (EVs). It is evident that the utilization of WPT technologies is on the verge of exponential growth. Design considerations for WPT at different power levels are quite different, and are discussed as follows. In the extreme low-power cases, IMDs [1–3] such as the pacemaker, cochlear implant, retinal prosthesis, neural recording microsystem, etc. only consumes a power level of milli-Watt or even lower. The form factor of the IMD power receiver is one of the most important concerns because it has to be as non-invasive as possible. For IMDs with a single channel or a few channels such as the pacemaker and the cochlear implant, a power level of micro-Watt would be sufficient [1]. For retinal prosthesis and neural signal recording, on the other hand, hundreds or thousands of channels are needed [2, 3], as simulations suggest that, for example, 600–1000 pixels will be required to provide visual function such as face recognition and reading [2]. In such a case, the power level would be in the milliWatt range, and fully on-chip integration is preferred such that no discrete component is needed, and the complete system could occupy just a few cubic millimeters. © Springer Nature Singapore Pte Ltd. 2018 Y. Lu, W.-H. Ki, CMOS Integrated Circuit Design for Wireless Power Transfer, Analog Circuits and Signal Processing, DOI 10.1007/978-981-10-2615-7_1
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1 Introduction of Wireless Power Transfer
High efficiency is of utmost importance, such that only little power is lost and being absorbed by the tissue that would cause potential damage. In the high-power regime such as charging up automotive battery systems for EVs, discrete high-voltage diodes and transistors are used to handle the power in the Kilo-Watt range. In between IMD powering and EV charging, wireless charging for portable/wearable devices is in the range of a few Watts. For consumer electronics, small size and compac
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