A team led by Professor Shi Yi and Associate Professor Qiu Hao from the School of Electronic Science and Engineering at Nanjing University in China has made significant progress in wireless energy transmission technology, bringing a new breakthrough to the power supply problem for invasive brain-computer interfaces.

Invasive brain-computer interfaces, due to the need for long-term implantation inside the human body, are restricted by biosafety concerns and the sealed physiological environment. They cannot rely on physical wired power supply and must adopt wireless energy transmission technology. However, the compact packaging structure leads to heat dissipation difficulties; if the heat converted from the chip's power consumption cannot be dissipated in time, it will trigger a series of problems. Therefore, improving energy conversion efficiency and reducing thermal dissipation have become core aspects of power management design. Although single-stage adjustable-voltage dual-output rectification technology is considered an ideal solution, it faces challenges such as limited effective charging windows, difficulty in regulating multiple output voltages, and susceptibility to heating from relying on PMOS active diodes.

To address these issues, the research team proposed a novel high-efficiency single-stage dual-output regulated rectifier topology, which can simultaneously charge both outputs within a half cycle. This breaks through the limitations of traditional time-multiplexing modes, enhancing load power, supply voltage quality, and energy conversion efficiency. Its innovative charge distribution mode alleviates the imbalance issue of dual-output load conditions, broadens the rated output current range, and enhances circuit stability and adaptability.

The chip was fabricated and verified using a 0.18μm CMOS process. Measurements show that under steady state, it achieved a peak efficiency of 92.2% and a peak load power of 131mW, with the dual output voltages stabilized at 3.3V and 1.6V, and maximum ripple voltages controlled at 50mV and 75mV respectively. During large load switching (×15), it exhibited high-speed response and avoided dual-output coupling interference, with several core metrics reaching high international levels. The relevant results were published online on April 16 in the top integrated circuit journal, IEEE Journal of Solid-State Circuits (JSSC). Zhuang Quanrong, a 2024 PhD student from the School of Electronic Science and Engineering, is the first author of the paper, with Associate Professor Qiu Hao and Professor Shi Yi serving as co-corresponding authors. Researcher Zhang Xin from the IBM Thomas J. Watson Research Center provided guidance. The research was funded by key projects of the National Natural Science Foundation of China and supported by the Engineering Center for Optoelectronic Materials and Chip Technology of the Ministry of Education, among others.