Bootstrapped FullSwing CMOS Driver for Low Supply Voltage Operation

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Bootstrapped Full-Swing CMOS Driver for Low
Supply Voltage Operation

• SpeakerHsin-Chi Lai
• m946602005_at_mail.ncue.edu.tw
• Advisor ?Zhi-Ming Lin

National Changhua University of
Education Graduate Institute of Integrated
Circuit Design
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From

• Garcia, J.C., Montiel-Nelson, J.A. and
  Nooshabadi, S., Bootstrapped full-swing CMOS
  driver for low supply voltage operation, Design,
  Automation and Test in Europe (DATE), vol. 1,
  6-10 March 2006.

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Outline

• Introduction
• Driver Circuit Structure
• Circuit Operation
• Results
• Conclusions

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Introduction

• Driving large capacitance loads limits the
  performance of CMOS circuits at low supply
  voltages.
• The bootstrap techniques have been shown to give
  high performance at low supply voltages.

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• Use of standard high speed BiCMOS drivers is not
  viable in low voltage portable electronic
  systems.
• A combined direct and indirect bootstrapped
  inverter driver (bfi-driver) in triple well CMOS
  technology is proposed.

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Counterpart circuit

• Compare with a counterpart direct bootstrap
  circuit 1.
• Where NMOS transistors M8 and M9 are the
  replacement for the original NPN bipolar
  transistors.

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Driver Circuit Structure
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• Two bootstrap capacitors Cb1 and Cb2, and only
  one inverter X0.
• M0 and M3 are charge the bootstrap capacitors Cb1
  and Cb2.
• M1 and M4 are the bootstrap transistors.
• M2 forms the pull-down network, while M5 forms
  the pull-up network.

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Circuit Operation
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• When Vin is Hi, the node 1 is set to Lo via the
  inverter X0, and M0 is turned on.
• Cb1 is charged to Vdd. M1, M4 and M5 are all
  turned off.
• M3 transistor is turned on causing Cb2 to charge.
• At the same time, M2 is driven by Vin and
  bif-driver is pulled down, the output Vout is set
  to low.

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• When Vin goes Lo, the node 1 is set to Hi, M0,
  M2, and M3 are turned off.
• M5 is turned on to pull-up the output.
• M4 turns on allowing the gate of M1 to be
  strongly driven low due to the bootstrapping
  effect of Cb2.
• The opposite bootstrapping effect of Cb1 directly
  couples to the output node Vout.

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• Cb, Cb1 and Cb2 are realized using NMOS
• transistors MCb, MCb1 and MCb2,

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Results
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As seen the Figure of Merit for proposed driver
is 23.6-37.5 times smaller.
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Conclusions

• A high speed and low power consumption
  direct-indirect bootstrapped full-swing CMOS
  inverter driver (bfi-driver) was presented.
• 0.13µm triple well CMOS technology
• At 1V , bfi-driver is 94 faster and consumes 22
  less power compared to a counterpart direct
  bootstrap circuit.

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• Thanks for your attention !!