On-Chip Hybrid Power Supply System for Wireless Sensor Nodes

Abstract

With the miniaturization of electronic devices, small-size but high-capacity power supply systems appear to be more and more important. A hybrid power source, which consists of a fuel cell (FC) and a rechargeable battery, has the advantages of long lifetime and good load-following capabilities. In this article, we propose the schematic of a hybrid power supply system that can be integrated on a chip compatible with present CMOS processes. For the on-chip, fuel-cell-based hybrid power system in wireless sensor node design, we propose a two steps optimization: (1) dynamic power management (DPM), and (2) adaptive fuel cell optimal power point tracking (AOPPT). Simulation results demonstrate that the on-chip FC-Bat hybrid power system can be used for wireless sensor nodes under different usage scenarios. Our proposed DPM method can achieve 12.9% more energy savings than the method without DPM. Meanwhile, implementing our AOPPT approach can save about 17% energy compared with the fixed architecture for the fuel cell system. For an on-chip power system with 1cm 2 area consumption, the wafer-level battery can power a typical sensor node for only about five months, while our on-chip hybrid power system will supply the same sensor node for two years steadily.