A 110nA quiescent current buck converter with zero-power supply monitor and near-constant output ripple

A 110nA quiescent current (IQ) buck converter for ultra-low power application is presented. A novel zero IQ pull-down structure, which consists in native NMOS and PJEF, is proposed to achieve zero-power supply monitor and save the total IQ. Implemented in 0.35um CMOS process, the converter realizes 78% efficiency in 1uA load and over 90% for load range from 5uA to 100mA. With adaptive-bias hysteresis comparator according to the load condition, near-constant output ripple is achieved in full load range without any efficiency deterioration.