“ Near-Threshold Computing: Reclaiming Moore’s Law
Through Energy Efficient Integrated Circuits ”
By Ronald G. Dreslinski, Michael Wieckowski, David Blaauw, Senior Member IEEE,
Dennis Sylvester, Senior Member IEEE, and Trevor Mudge, Fellow IEEE
Presented by: Abdullah Almohaimeed
© Agenda:
1- introduction.
2- NTC Concept.
3- NTC analysis
4-Barriers of NTC.
5- Addressing NTC barriers.
6- future direction.
7- conclusion.
Introduction:
# Moore’s Law and its obstacles.
# How to address this problem from different view designers.
# The important of energy:
• High-Performance Platforms.
• Personal computing platforms.
• Sensor-based platforms.
# The desire of designers in this field.
NTC Concept:
 Operating the devices near the threshold voltage (Vth).
 Result of energy consumption in modern CMOS.
 determine the optimal of Vdd:
 Vdd > Vth : energy is highly sensitive to Vdd.
 Vdd ≈ Vth : 10 times of energy reduction at the expense of 10
times degradation performance.
 Vdd< Vth: circuit delay increases exponentially with Vdd,
causing leakage energy.
Energy and Delay in different supply voltage operation
NTC analysis:
 Example of precessors: Subliminal and Phoenix
processors.
 only a modest increase in energy at the NTC region
(around 0.5 V), while frequency characteristics at that
point are significantly improved.
NTC Barriers:
 A. Performance Loss:
e.g. 45 nm technolgy the fanout of four inverter delay at
NTC supply is 10x slower than at nominal supply.
 B. Increased Performance Variation:
NTC designs display increase in performance
uncertainty.
 heightens sensitivity to temperature and supply ripple
 C. Increased Functional Failure:
In particular, the mismatch in device strength due to
local process variations from such phenomena as
random dopant fluctuations(RDF).
Addressing NTC Barriers:
 Addressing performance loss:
1- Cluster-based Architecture:
 by using of NTC-based parallelism. This method will
regain 10–50X of the performance, while remaining
energy efficient.
2- Device Optimization:
B. Addressing Performance Variation
To address these problems by applying:
 1) Soft Edge Clocking:
 Soft-edge flip-flop
 2) Body Biasing:
 is a well known technique for adapting performance
and leakage to global variation of process, voltage, and
temperature.
C. Addressing Functional Failure:
The increased of sensitivity lead to a highly rise in
functional failure.
To address this problem by:
 1- Alternative SRAM Cells:
 2-SRAM Robustness Analysis Techniques
 3-Reconfigurable Cache Designs:
Future direction:
 Canary Circuits: predict the delay failure of a pipeline.
 The variation-constrained logic using in situ circuitry
Conclusion:
 Moore’s law
 NTC principle
 Problems of NTC and their soultion
Questions?!
Thank you so much for attention