11.2 A Fully Integrated Resonant Switched-Capacitor Converter with 85.5% Efficiency at 0.47W Using On-Chip Dual-Phase Merged-LC Resonator

Fully integrated power management is important for a variety of applications spanning performance and mobile computing, embedded systems, and communications. However, monolithic integration has been elusive due to the limitations of passive components - especially inductors, which scale poorly to small size and are difficult to integrate. Planar spiral inductors are attractive from an integration perspective, but tend to have low inductance and energy-storage capability, low quality factor in mid-MHz frequencies, and high skin, proximity, and substrate-loss effects [1-3]. Buck converters are not well suited to full integration due to tradeoffs between inductive energy storage and switching frequency. However, recently developed hybrid-resonant switched capacitor (SC) topologies may be promising when combined with spiral magnetics, e.g., [1], [4], as they leverage higher-density on-chip capacitors while reducing the size and energy storage requirements of inductors. Compared to pure SC approaches, they tune out the reactive impedance of capacitors to operate at lower frequencies, reducing bottom plate and charge-sharing losses. They also have capabilities for voltage regulation and light-load operating modes [3].