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A CMOS CHARGE PUMP for LOW
VOLTAGE APPLICATION
By:- GAURAV KUMAR3136602
Under the Guidance of
Prof. R. K . SHARMA
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Objectives
Introduction Charge Pump
Dickson Charge Pump
NCP-2 Charge Pump Proposed Charge Pump
Simulation Results
Applications
Conclusion
References
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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.
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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.
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Cont..
Basic circuit of charge pump
Most MOS charge pumps are based on Dicksoncharge pump.
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Types of Charge Pump
Dickson Charge Pump
NCP-2 Charge Pump
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DICKSON CHARGE PUMP
Dickson Charge pump is shown in figure below.
Clk and clkbar are in anti-phase.
4-Stage Dickson charge Pump
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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
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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.
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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
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Cont.
Static Charge Pump
A four stage charge pump using static CTSs.
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Cont.
Dynamic charge pump.
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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.
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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.
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Cont..
The Proposed charge pump and associated waveforms at the pumping nodes
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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.
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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
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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
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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.
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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_pump8/13/2019 Cmos Charge Pump1
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THANK
YOU
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QUESTIONS