Charge pump circuits

摘要

Charge pump circuits for stepping up high voltages for flash memory array are disclosed. A first circuit comprises a plurality of series-coupled charge pumps having pump capacitors connected to each pump stage. A first group of charge pumps of the pump circuit are AC coupled through pump capacitors to two non-overlapping pulse trains. To reduce the high voltage that a pump capacitor has to withstand, each pump capacitor after the first group is connected to an earlier pump stage instead of the non-overlapping pulse trains. Therefore, the charge pump circuit can output voltage higher than the breakdown voltage of the pump capacitors. A second circuit comprising a configurable charge pump circuit is also presented. By connecting selected pump stages through diode paths to the output of the charge pump circuit and having a plurality of pulse train inputs, the charge pump circuit can be configured as a high voltage low current charge pump or a low voltage high current charge pump dependent on how pulse train signals are provided to the pulse train inputs. Finally, an improved structure for pump capacitors used in the charge pump circuit is presented.