Energy-Efficient Power Management Interface With Adaptive HV Multimode Stimulation for Power-Sensor Integrated Patch-Type Systems.

Abstract

An energy-efficient power management interface (PMI) with adaptive high-voltage (HV) stimulation capability is presented for patch-type healthcare devices where power management and sensor readout circuits are integrated. For efficient power supply, it proposes a multimode buck converter with an adaptive mode controller, delivering 95.6% peak power conversion efficiency and over 90% efficiency across a wide 4-440 mA output current range. For energy-efficient stimulation, a HV stimulation system is designed to perform mode-adaptive on/off control, where the charge pump (CP) is adopted for periodic power saving. The CP output is adaptively tuned to minimize the stimulator's power waste by utilizing a bio-impedance path in the sensor circuit. The stimulation core supports multimode functionality of current-/voltage-controlled stimulations with monopolar and bipolar modes, providing ten kinds of various stimulation waveform shape. For efficient system operation, battery interface circuits are included to monitor state-of-charge (SOC) conditions, and a device power adjustment scheme is proposed to provide SOC-based maximum 28% power reduced optimal operation of high-resolution and low-power. The power-sensor integrated circuits were fabricated in a 0.18-μm CMOS process, and the proposed schemes were experimentally verified. For system-level feasibility, a patch-type device prototype was manufactured, and both power and bio-signal interfaces were functionally demonstrated.