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This paper presents a systematic design of a high-efficiency magnetic resonant wireless power transfer (MR-WPT) system for biomedical implants based on the unconventional multisine (MS) transmission waveform. The MS waveform featuring a high peak to average power ratio can boost the system efficiency with an elaborate design. Optimizations on flexible coil, system model, and rectifier design are all considered to strengthen its efficiency improvement as well as eliminate its drawbacks. With all the proposed optimizations implemented, the MS waveform has been applied for the first time in practical MR-WPT system for in vivo power delivery. A 6.78-MHz MR-WPT system with 18-mm implant depth is realized for wirelessly powering a spinal cord stimulator. It achieves an overall system efficiency (both coils and rectifier included) of 50.7% with a three-tone 230-kHz tone spacing MS waveform postimplantation in the rodent model. Low specific absorption rate and the tissue temperature rising from electromagnetic fields in the body are also verified to guarantee a safe and practical wireless power link for biomedical implants. [ABSTRACT FROM AUTHOR]

This letter presents a reconfigurable diode topology which obtains the independently tuned ultra-low threshold voltage and large breakdown voltage simultaneously. Measured I-V curves show that the proposed topology obtains both ultra-low threshold voltage (250 mV) and tunable breakdown voltage up to −51 V. By applying the topology in rectifier design, high efficiency of above 50% can be maintained within a wide power range from 0.1 W to above 10 W in an inductive wireless power transfer (WPT) test environment. It provides a practical diode topology design for rectifiers to maintain high efficiency for large power variation scenarios such as coil misalignment. [ABSTRACT FROM PUBLISHER]

This letter presents a novel dual-band rectifier with extended power range (EPR) and an optimal incident RF power strategy in the settings where the available RF energy fluctuates considerably. It maintains high power conversion efficiency (PCE) in an ultra-wide input power range by adopting a pHEMT in the proposed topology. Simultaneous RF power incident mode is proposed and preferred to the traditional independent mode for multi-band harvesting. Measured results show that more than 30% PCE is obtained with input power ranging from -15~dBm to 20 dBm and peak PCE of 60% is maintained from 5 to 15 dBm. Positive power gain is achieved from -20~dBm to more than 10 dBm. Investigation about the effect of RF power incident ratio on dual-band harvesting's performance is presented and it provides a good reference for future multi-band harvesting system design. [ABSTRACT FROM PUBLISHER]