An efficiency enhance mixed-structure charge pump

An enhanced high-efficiency switching-capacitor DC-DC voltage converter based on the combination of charge transfer switch (CTS) charge pump and cross-coupled output stage is presented. Some motivated methods to overcome the reverse charge sharing problem of traditional CTS charge pump are discussed and a new mixed structure is proposed to conquer the remaining problem of threshold drop at the output stage. The charge pump proposed can operate at 1MHz switching-frequency on the 0.1µF pump-capacitors. After the simulation by using HSPICE 0.35 µm TSMC process, our work can convert the input low DC-voltage (V
DD
=1.5V) up near to 5 times of it (V
OUT
= 7.4483V) and the pump-efficiency reaches to 99.31%. The new proposed charge pump circuit is suitable for low-voltage applications in CMOS process because there is no threshold voltage drop in every stage even at the output stage. A great achievement has been obtained.