Abstract – A new power saving concept forconventional four-phase charge pump is presented. Based on multi-step chargingand the charge sharing concept, the charge pump is able to reduce the overallpower consumption by 18.27% compared to aconventional four- phase charge pump and by compared to a charge sharing chargepump with 11V output voltage. Indexterms – Charge pump, EEPROM, NVMs I. INTRODUCTIONChargepump circuits charges upward to produce voltages higher than the regular supplyvoltage 1.
They are usually applied to the non volatile memories (NVMs), suchas Electrically erasable Programmable Read-only memory (EEPROM) or flash memoryto erase or to write the floating gate devices 2.Classicalcharge pumps are based on Cockcroft and Walton voltage multiplier 3. But, InCockcroft Walton multiplier ,chip monolithic integration is hard to reach.Therefore, to overcome this limitation, Dickson voltage multiplier is usedwhich is based on a diode chain is proposed in 4.It has poor conversion efficiencybecause body bias effect 5 on threshold voltage (VTH).Manyconfigurations have been developed to reduce the influence of the VTH onthe functionality of the charge pump by canceling the input of the body effect.
In6, the charge pump using a four–phase clock and boost capacitors on theswitch transistor eliminates the influence of VTH. The circuit of aconventional four-phase boosted charge pump is described in fig 1. CLK3 and CLK4are two overlapped clock phases used to charge the pump capacitors. CLK2 andCLK4 are two non-overlapped clocks used to boost the gate voltage of the chargetransfer device during charge transfer. However,all of these configurations do not completely optimize power consumption.
Several studies have been led to reduce the power consumption. In 7, the charge sharing technique appliedto a conventional four-phase charge pump to reduce the power consumption. Thepaper is organized as follows, Section II presents the charge sharing concept.Section III presents the multi-step concept and its association with the chargesharing concept. In Section IV, simulation results are presented . II. CHARGE SHARING CHARGE PUMPpaper