A 40.68-MHz Fully-Integrated Voltage/Current-Mode Dual-Output PMU for Wireless Neural Implants

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Integrated Circuit Design

Background:

• Wireless neural implants require efficient and flexible power management solutions.
• Existing power management units often struggle with varying load conditions and on-chip integration challenges.

Purpose of the Study:

• To present a fully-integrated, single-input, dual-output power management unit (PMU) for mm-scale wireless neural implants.
• To enable flexible power distribution and configurable voltage ratios through dual-mode operation (voltage/current).

Main Methods:

• Implemented a dual-mode PMU utilizing active full-wave rectification in voltage mode and current mode rectification for different output loads.
• Employed a 40.68 MHz operating frequency to minimize external component requirements.
• Integrated a novel resonance breakup switch for self-sufficient cold start-up.

Main Results:

• The chip successfully regulated two outputs ($V_{LV}$=1V, $V_{HV}$=2V) simultaneously.
• Achieved a peak power conversion efficiency of 85.87% and peak end-to-end efficiency of 17.32% for the low-voltage output.
• Demonstrated minimal efficiency drop (2.38%) when regulating both outputs under varying load conditions.

Conclusions:

• The developed dual-mode PMU offers a flexible and efficient solution for powering wireless neural implants.
• The on-chip integration and novel startup mechanism pave the way for smaller, more autonomous implantable devices.