This chapter describes the fundamental principles of near-field wireless telemetry through inductive links and provides insight with respect to the choice of design parameters, carrier frequency, data modulation schemes, methods of theoretical analysis, and electromagnetic safety. After presenting the simplified models for the inductance and mutual coupling among conductive loops, non-resonant and resonant inductive links are described to show the basic idea behind magnetic resonance in inductive power transmission. The power transfer efficiency (PTE) for conventional inductive links has been derived based on the lumped circuit parameters, which leads to a simplified design procedure to optimize the coil geometries for achieving the highest PTE. Different carrier-based modulation schemes are presented followed by a brief discussion on single carrier versus multi-carrier telemetry links for high bandwidth and robust data transmission in the presence of the power carrier. Finally, a new carrier-less modulation scheme called pulse harmonic modulation (PHM) has been proposed, which can offer high data rate in implantable medical devices (IMDs) without dissipating much power on the implantable side.
All Science Journal Classification (ASJC) codes