Four Monolithically Integrated Switched-Capacitor DC-DC Converters With Dynamic Capacitance Sharing in 65-nm CMOS

We present a network of dynamic capacitance sharing (DCS) switched-capacitor converters that increase the range of efficient voltage regulation for multiple independent loads while reducing area overhead. Since maximum power dissipation is fixed for a single chip due to thermal constraints, the proposed converters consider the overall power budget of multiple voltage-scalable loads to dynamically share energy storage area, allowing the dynamic allocation of energy storage clusters on-demand. Our DCS converters utilize a feedback control scheme including both capacitance and frequency modulation, which leads to the order of 10-100ns voltage settling times. A test chip with 16 clusters and four regulator control loops is fabricated in 65-nm bulk CMOS process. For a 2.3V input, our DCS converters achieve 0.742V at 38.1mA to 1.367V at 298mA output with peak efficiency of 70.9% at 550-mW/mm(2) power density. Regulator area for the four-load network is reduced by up to 70% when operating under a power constraint compared with the stand-alone per-load regulators capable of supporting an equivalent range of operating voltages.