Download Utilizing Reverse Short Channel Effect for Optimal

Low Power and High Speed Multi Threshold
Voltage Interface Circuits
By
Sherif A. Tawfik and Volkan Kursun
Presented by
Ramasamy Ethiraj
Contents
• Introduction
• Standard Feedback-Based Level Converters
• Proposed Multi-Vth Level Converters
• Delay and Power consumption of level Converters
- Comparison of level converters
- The performance of level converters under Supply Voltage
and Process Parameter Variations
- Multi Vth-CMOS Technology
• CONCLUSION
Introduction
• Scaling the supply voltage to reduce the power
• Lower supply will degrade the speed
• Multi-VDD Techniques and Conventional Level converters
are introduced.
• Conventional Level converters will introduce DC current
and feedback circuit (hence slow response)
• Multi-Vth Level converters will eliminate DC current and
Feedback circuit.
Standard Level Converters 1 (LC1)
• VDDL is directly connected to M3 & M4 – DC path. So high power
• Feedback circuit – more delay.
• M1 & M2 should be large, because VDDL is directly connected.
Result in large capacitance and area
Standard Level Converters 2 (LC2)
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VDDL is not directly connected to PMOS – still some DC current
Feedback circuit – more delay.
More device count- more delay and power
M2 should be large, because VDDL is directly connected. Result in
large capacitance and area
Proposed Multi-Vth Level Converter1
(PC1)
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Vth-M2 should be more negative than VDDL –VDDH to avoid DC current
No feedback circuit – less delay.
less device count- less delay, area and power
Smaller transistor sizes.
Proposed Multi-Vth Level Converter2
(PC2)
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Vth-M2 should be more negative than VDDL –VDDH to avoid DC current
Multi Vth is used for M3.
Lowest delay compare to other converters
No feedback circuit – less delay.
Smaller transistor sizes.
Proposed Multi-Vth Level Converter2 (PC2)
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•
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Vth-M2 should be more negative than VDDL –VDDH to avoid DC current
M3,M4,C is removed for lower VDDL
No feedback circuit – less delay.
Smaller transistor sizes.
Simulation Setup
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0.18um technology
VDDH = 1.8V
Simulated for different VDDL : 0.5, 1 and 1.2V
Wn = Wmin, Wp = 2.5Wn
Delay is measured between input of ID and Node2
Power consumption measured for entire setup
Optimum Delay and Power measurements
Normalized to LC2
The performance of level converters
under Supply Voltage and Process
Parameter Variations
Power and Delay comparison – LC2 vs. PC2
for Power optimized circuit (VDDL = 1.2V)
Power and Delay comparison – LC2 vs. PC1
for Power optimized circuit (VDDL = 1V)
Power and Delay comparison – LC2 vs. PC1
for Power optimized circuit (VDDL = 0.5V)
Vth-M2 vs. Power and Delay
Conclusions
• Multi-Vth level converters has up to 78%
less delay compare to standard level
converters
• 70% less power consumption
• Less Device count and size – minimum
Area
• Wide range of threshold voltages
• High speed and low power.
Thank You