With increasing recognition of green house gas emission as a major contributor to global warming, and that fossil fuels are finite resources that would eventually dwindle, green electronics, a commitment toward designing more energy-efficient products, is not only an environmental, social, and ethical imperative for the integrated circuit research community, but also a shrewd business practice for industry.
This dissertation discusses various mixed-signal VLSI techniques at system and circuit (transistor) levels that would help build energy-efficient green electronics, which are instrumental for current consumer applications and future sustainable renewable-energy economy. At system level, a truly effective power management scheme should be a holistic solution involving system software, VLSI architecture, and silicon IPs. Sleep-mode efficiency is pointed out as the bottleneck for low power battery-powered applications, and around 30% battery runtime extension is estimated based on published experimental data if sleep-mode efficient power management IPs are available and used in place.
At circuit level, a number of linear regulator and switch-mode power converter designs are presented. A sleep-mode ready, current-area efficient capacitor-free low drop-out regulator with input current-differencing is designed, fabricated, and measured in 0.5 um CMOS process. A long-sleep model that improves the light-load efficiency of DC-DC Buck converter under mW to uW load during system sleep-mode is also proposed. The common theme among the designs is high efficiency and full on-chip, which are uniquely required by portable and battery-powered applications; The key innovation is the enhanced sleep-mode efficiency, which is driven by, and effectively supports the holistic power management solution.