An On-/Off-Time Sensing-Based Load-Adaptive Mode Control of Triple Mode Buck Converter for Implantable Medical...

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Power Electronics

Background:

• Implantable medical devices (IMDs) often require battery replacement surgeries, posing risks and increasing healthcare costs.
• Wireless power transfer (WPT) offers a promising solution to power IMDs, reducing the need for invasive procedures.
• Efficient power management is crucial for IMDs to maximize device longevity and minimize energy consumption.

Purpose of the Study:

• To develop and demonstrate a load-adaptive triple-mode buck converter for IMDs powered by WPT.
• To achieve high power conversion efficiency (PCE) and low power consumption across a wide range of load currents.
• To enable seamless mode transitions between pulse width modulation (PWM), pulse frequency modulation (PFM), and ultra-low power (ULP) modes.

Main Methods:

• A triple-mode buck converter utilizing on-/off-time sensing for load-adaptive control was designed.
• The converter integrates PWM, PFM, and ULP modes, controlled by on-time and off-time sensors for mode switching.
• Fabrication was performed using TSMC 0.18 µm CMOS technology, with input voltage ranging from 2.2-5.0 V and output voltage at 1.8 V.

Main Results:

• The proposed converter demonstrated seamless mode transitions under dynamic load changes (0.05-200 mA).
• A peak power conversion efficiency (PCE) of approximately 94.3% was achieved at a load current of 80 mA.
• The minimum PCE observed was approximately 65.4% across the tested load current range, indicating efficient operation.

Conclusions:

• The on-/off-time sensing-based load-adaptive control effectively manages power consumption in IMDs.
• The triple-mode buck converter achieves high PCE and efficient operation for WPT-powered IMDs.
• This technology significantly enhances the feasibility and reduces the invasiveness of long-term IMD applications.