Design of monolithic master-slave SC power converter for ultra-low power energy-harvesting microsensors

Driven by the proliferation of self-powered biomedical and wireless sensing microsystems, integrated high-efficiency, low-voltage DC-DC converters are in high demand. This paper first analyzes the state-of-the-art switched-capacitor (SC) power converter topologies, with a focus on minimizing the reversion power in the charge pump power stage and the static power in the controller. A new SC power converter is then proposed, with a master-slave complementary charge pump power stage and a feedback controller that purely operates in ultra-low-power subthreshold operation region. The SC power converter was designed with IBM 180-nm CMOS process. Fully transistor-based HSPICE simulation results show that the efficiency of the converter stays above 76.7% from 100 ¿W to 1 mW, with a maximum efficiency of 87.9%. The subthreshold controller consumes only 20-¿W power. In comparison with the state-of-the-art counterparts, the load transient performance is also significantly improved.