Centimeter-Range Inductive Radios

Abstract

This chapter describes the fundamental principles of cm-range wireless telemetry through inductive links and provides insight in regards to the methods of analysis, choice of modulation schemes, carrier frequencies, and coil design. After presenting simplified models for the inductance and mutual coupling of conductive loops, the inductive link equivalent network is derived to be used for analysis of inductive data links. Different carrier-based modulation schemes such as amplitude-shift keying (ASK), frequency-shift keying (FSK), and phase-shift keying (PSK) are discussed for near-field simultaneous data and power transmission in different applications such as implantable microelectronic devices (IMDs), radio frequency identification (RFID), and smart cards. Data communication through load-shift keying (LSK) is also discussed followed by presenting the pulse-based schemes for low-power communication. Finally, new pulse-harmonic modulation (PHM) and pulse-delay modulation (PDM) schemes that offer high data rate in IMDs without dissipating much power on the implantable side are presented.