An on-chip high voltage generator applicable to low voltage flash memory is introduced. Bootstrapped gate transfer switches of two parallel paths suppress the voltage loss due to threshold voltage drop of transfer transistors. The simulated results demonstrate that proposed circuit designed with NMOS transistors having 0.8 volt threshold voltage works like an ideal charge pump circuit near 1.0 volt range with enough current driving capability.

A new CMOS DC voltage doubler with nonoverlapping switching control is proposed, in order to eliminate the dynamic current loss during switching as well as the threshold voltage drop of the serial switches. The simulated results at 1.5 V show that the maximum power efficiency is improved with about 30%, whereas the efficiency in the low output current region is larger than 5 times compared to the conventional voltage doublers. This proposed CMOS DC voltage doubler can be used as a VPP generator of low voltage DRAM's.