A High-Efficiency Split–Merge Charge Pump for Solar Energy Harvesting

An energy-efficient charge pump (CP) for solar energy harvesting is presented. A multistep split–merge charge transfer operation is introduced to replace the traditional one-step charge transfer process. Theoretically, this method increases the amount of charge transferred by up to 26% while reducing the Joule heat power loss by up to 7%. A five-stage complementary split–merge CP was designed and fabricated in a 0.13-
$\mu\text{m}$
CMOS process. Measured results show an averaged 15.2% improvement of power conversion efficiency and a 1/8-fold reduction of output voltage ripple.