The delivery of high-quality supply voltage with minimal loss is essential for energy-efficient and reliable electronics. The challenges for power conversion, regulation, and delivery are different for high-performance high-power microprocessors and ultra-low-power wireless sensor nodes operating from harvested energy. Our research is designing high-efficiency and fast response monolithic converters (buck or boost) and develops on-line real-time control for optimal system level energy-efficiency considering energy source, converter, and digital load. Application to energy harvesting and processor power delivery are investigated.
Power Regulators for Energy Harvesting: We are designing low minimum input, high-efficiency, and load-adaptive synchronous and asynchronous boost, buck, and buck-boost converters for ultra-low-power sensor nodes. Test-chips designed in 130nm CMOS has achieved sub-10mV operation, less than 200nA bias current, and higher than 80% efficiencies.
Power Regulation for High-Performance Processors: We are designing integrated power converters/regulators with high and variable conversion ratio for multi-core processors with intelligent power management policies like DVFS and power gating. We are exploring hybrid converters, Single-Inductor Multiple-Output (SIMO) converters, and linear regulators. The integration of digital and load-adaptive control with the converter is a being pursued.
Exploiting Emerging Packaging Technology for Power Delivery: Emerging packaging technologies like 3D die-stack or interposers (2.5D) bring in intriguing challenges as well as new opportunities for power delivery. We are exploring the interaction between packaging technologies, converter design, and power control principles. Design of 3D power converters with on-chip or on-package passives is a challenging goal being pursued in the group.