Abstract – A new power saving concept for
conventional four-phase charge pump is presented. Based on multi-step charging
and the charge sharing concept, the charge pump is able to reduce the overall
power consumption by 18.27% compared to a
conventional four- phase charge pump and by compared to a charge sharing charge
pump with 11V output voltage. Index
terms – Charge pump, EEPROM, NVMs I. INTRODUCTIONCharge
pump circuits charges upward to produce voltages higher than the regular supply
voltage 1. They are usually applied to the non volatile memories (NVMs), such
as Electrically erasable Programmable Read-only memory (EEPROM) or flash memory
to erase or to write the floating gate devices 2.Classical
charge pumps are based on Cockcroft and Walton voltage multiplier 3. But, In
Cockcroft Walton multiplier ,chip monolithic integration is hard to reach.
Therefore, to overcome this limitation, Dickson voltage multiplier is used
which is based on a diode chain is proposed in 4.It has poor conversion efficiency
because body bias effect 5 on threshold voltage (VTH).Many
configurations have been developed to reduce the influence of the VTH on
the functionality of the charge pump by canceling the input of the body effect. In
6, the charge pump using a four–phase clock and boost capacitors on the
switch transistor eliminates the influence of VTH. The circuit of a
conventional four-phase boosted charge pump is described in fig 1. CLK3 and CLK4
are two overlapped clock phases used to charge the pump capacitors. CLK2 and
CLK4 are two non-overlapped clocks used to boost the gate voltage of the charge
transfer 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 applied
to a conventional four-phase charge pump to reduce the power consumption. The
paper is organized as follows, Section II presents the charge sharing concept.
Section III presents the multi-step concept and its association with the charge
sharing concept. In Section IV, simulation results are presented .
II. CHARGE SHARING CHARGE PUMPpaper