Cmos Charge Pump1

8/13/2019 Cmos Charge Pump1

1/22

A CMOS CHARGE PUMP for LOW

VOLTAGE APPLICATION

By:- GAURAV KUMAR3136602

Under the Guidance of

Prof. R. K . SHARMA


2/22

Objectives

Introduction Charge Pump

Dickson Charge Pump

NCP-2 Charge Pump Proposed Charge Pump

Simulation Results

Applications

Conclusion

References


3/22

INTRODUCTION

Power consumption is crucial consideration in

design of VLSI

Most common method to reduce the power

consumption is to reduce the power supply

voltage.

Basic circuit used is charge pump.


4/22

CHARGE PUMPCharge Pump circuits are switching mode power

converters.

Charge pumps are also called level shifter.

Basic Charge pump transfers charge packets from

power supply to output, using only capacitor and

switches.


5/22

Cont..

Basic circuit of charge pump

Most MOS charge pumps are based on Dicksoncharge pump.


6/22

Types of Charge Pump

Dickson Charge Pump

NCP-2 Charge Pump


7/22

DICKSON CHARGE PUMP

Dickson Charge pump is shown in figure below.

Clk and clkbar are in anti-phase.

4-Stage Dickson charge Pump


8/22

Cont.. The Voltage fluctuation is given by

V= Vclk.

+

(+)

o Vclkis voltage amplitude of clock signal

o Cis pumping capacitor

o Csis parasitic capacitance

o Iois output current and

o f is frequency of clock

o

The Voltage Gain of Nthstage charge pump

Gv=VN -VN-1

And Pumping Gain :

Gv= V- Vth(N)

Output Voltage is given by

Vout ()+1=1


9/22

The difference between the source and the bulkterminals voltages increases in the later stages ofthe circuit.

The threshold voltage Vthof the diode-connectedNMOS becomes larger due to body effect. So thepumping efficiency reduced by the Body effect.

Modified Dickson charge pump is called NCP-2charge pump.

Cont.


10/22

NCP-2 Charge Pump

NCP-2 stands for New Charge Pump-2

It is Modified Dickson Charge Pump which control

the increase in threshold voltage due to body effect.

It uses pass transistor .

it can be of two type

A. Static charge pumpB. Dynamic charge pump


11/22

Cont.

Static Charge Pump

A four stage charge pump using static CTSs.


12/22

Cont.

Dynamic charge pump.


13/22

Cont.

The output of the NCP-2 charge pump is diodeconnected NMOS transistor and this leads toreduction of output voltage. due to body effect.

Reverse charge flow problem.

Several technique such as four clocking , higherclock signal for output stage to increase output ofcharge pumps are proposed.


14/22

PROPOSED CHARGE PUMP

Circuit is based on crossconnected NMOS Cell.

Consist of two Non-overlapping clock signalsto provide the charge

pumping action.

The voltage signals atOUTA and OUTB are outof phase.


15/22

Cont..

The Proposed charge pump and associated waveforms at the pumping nodes


16/22

Cont..

Output of proposed charge pump is 5xVDDin

ideal conditions.

At any of the stage, the voltages Vgd, Vgshave

a maximum of VDD, the supply voltage. As a

result, the gate oxide reliability is increased

and stressing of gate oxide due to high DC

voltage is avoided.


17/22

SIMULATION RESULTSimulated output voltages of Dickson,

NCP-2 and Proposed charge pump forDifferent input voltages is shown in fig.6

Simulated output voltages for 4-stage

Charge pump with VDD=1 V.Simulated output voltages for

Charge pump with VDD=2 V.

Fig.6


18/22

Future Applications

Charge Pump Regulator for Micro-colour TFT

Panel.

Phase Lock Loop.

Memories such as EEPROM, Flash Memories.

As LCD or white LED drivers


19/22

CONCLUSION

A charge pump in standard CMOS processsuited for low voltage is presented. The

influence of the threshold voltage of the switch

transistor is almost eliminated and thepumping efficiency of the circuit is improved.


20/22

REFERENCES

[1] Chun Yu Cheng, Ka Nang Leung, Yi Ki Sun and Pui Ying Or Design of a Low-Voltage CMOS Charge Pump,IEEE J.2008

(http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4459568&tag=1)

[2] Mohammad Mahdi Ahmadi and Graham Jullien A CMOS charge pump for low

voltage operation, IEEE J. 2000

(ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=857500)

[3] Shantanu A. Bhalerao, Abhishek V. Chaudhary, Rajendra M. Patrikar CMOS Low

Voltage Charge Pump,IEEE J. 2007

[4] Y. Moisiadis, I. Bouras, A. Arapoyanni A CMOS charge pump for low voltage

application.,IEEE J. ISCAS 2000may 28-31

http://en.wikipedia.org/wiki/Charge_pump
http://en.wikipedia.org/wiki/Charge_pumphttp://en.wikipedia.org/wiki/Charge_pump


21/22

THANK

YOU


22/22

QUESTIONS

Cmos Charge Pump1

Documents

Transcript of Cmos Charge Pump1