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 voltagescalable 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 10–100 ns voltage settling times. A test chip with 16 clusters and four regulator control loops is fabricated in 65 -nm bulk CMOS process. For a 2.3 V input, our DCS converters achieve 0.742 V at 38.1 mA to 1.367 V at 298 mA output with peak efficiency of 70.9% at 550 -mW/mm2 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 perload regulators capable of supporting an equivalent range of operating voltages.