Maximizing Energy Harvesting in a Miniaturized Implant With an Integrated Coil Receiver

In this brief, a fully integrated energy harvester employing an on-chip coil and a voltage multiplier rectifier is proposed. The differential, multi-stage rectifier is optimized recurring to a genetic algorithm with the objective of maximize the power delivered to the load $(\mu \text{W}$ power transfer level) while minimizing area and start-up voltage. The rectifier is one of the most critical components in wireless-powered systems, generating a stable DC supply voltage, its efficiency is the main limiting factor in the achievable power budget. When implemented inside an implant, the circuit should occupy the minimum possible area and present a low start-up power as in the context of most applications, the amount of energy that reaches the receiver is extremely small. Simulation results show that the proposed circuit performs with an efficiency of 38% delivering a stable 1.16 V DC voltage to a 100 k Omega load, providing an output power of 14.9 mu W and solely occupying an area of $8750 mu m(2). Post-fabrication experimental results are presented, where a small inductive link employing a fully integrated receiver coil is used with the rectifier. A maximum power transfer of 12.5 mu W is achieved, with the inductive link operating at 915 MHz.

Automated summary

In this paper, a fully integrated energy harvester with an on-chip coil and voltage multiplier rectifier is proposed and optimized using a genetic algorithm. The results show that the circuit achieves high efficiency and stable power transfer while occupying a small area and requiring low start-up power. Experimental results confirm the effectiveness of the proposed design.