Development of Monolithic Switched-Capacitor Power Converters for Self-Powered Microsystems

摘要

Modern electronics continues to push past boundaries of integration and functional density toward elusive, completely autonomous, self-powered microsystems. As systems continue to shrink, however, less energy is available on board, leading to short device lifetimes (run-time or battery life). Extended battery life is particularly advantageous in the systems with limited accessibility, such as biomedical implants and structure-embedded micro-sensors. The power management process usually requires compact and efficient power converters to be embedded in these microsystems. This dissertation introduces switched-capacitor (SC) power converter designs that make all these techniques realizable on silicon.Four different integrated SC power converters with multiple control schemes are designed here to provide low-power high-efficient power sources. First, a monolithic step-down power converter with subthreshold z-domain digital pulse-width modulation (DPWM) controller is proposed for ultra-low power microsystems. The subthreshold design significantly reduces the power dissipation in the controller. Second, an efficient monolithic master-slave complementary power converter with a feedback controller that purely operates in subthreshold operation region is discussed to tailor for the aforementioned ultra-low power applications. Third, we introduce an efficient monolithic step-down SC power stage with multiple-gain control and on-chip capacitor sizing for self-powered microsystems. The multiple-gain control helps the converter to constantly maintain high efficiency over a large input/output range. The size-adjustable pumping capacitors allow the output voltage to be regulated at different desired levels, with a constant 50% duty ratio. The monolithic implementations in these three integrated CMOS power converters effectively suppress noise and glitches caused by parasitic components due to bonding, packaging and PCB wiring. Fourth, an efficient step-up and step-down SC power converter with multiple-gain closed-loop controller is presented. The measurements and simulation results in these four power converters demonstrate the techniques proposed in this research. The approaches presented in this dissertation are evidently viable for realizing compact and high efficient SC power converters, contributing to next generation power-efficient microsystems designs.