A new high efficiency CMOS voltage doubler

Abstract

A charge pump cell is used to make a voltage doubler using improved serial switches. The PMOS transistor used for the serial switch is analyzed and a model suitable for simulation is described. The importance of capacitors is shown with plots of efficiency versus load and stray capacitance. Several problems arising at low voltage or high frequency are developed and some optimizations are presented. The substrate current is totally suppressed by the technique of bulk commutation. An efficiency of 94% has been reached using external capacitors.