A high efficiency all-PMOS charge pump for 3D NAND flash memory

In this paper, an improved four-phase all PMOS charge pump based on the Pelliconi structure is proposed with high voltage boosting efficiency, strong driving capability and large power efficiency. The proposed charge pump uses a complementary structure to solve the voltage driving problem in the conventional charge pump structures. Two auxiliary substrate switching PMOS transistors are added to mitigate the PMOS body effect. The degradation of the output voltage and power efficiency caused by the high threshold voltage drop of high-voltage transistors is eliminated by means of dynamic gate control structure. The proposed charge pump is implemented in 2Xnm process of 3D V-NAND with all PMOS transistors. The simulation results show that the output voltage of proposed 9 stages charge pump can be reached to 23.24V, and the maximum power efficiency of 82.5% can be achieved with 20uA load current, under 20 MHz clock frequency for a power supply voltage of 3 V.