Lei Wang

Bio: Lei Wang is an academic researcher from University of Connecticut. The author has contributed to research in topics: Redundancy (engineering) & Energy (signal processing). The author has an hindex of 18, co-authored 105 publications receiving 1265 citations. Previous affiliations of Lei Wang include Hewlett-Packard & University of Illinois at Urbana–Champaign.

A Survey on Chip to System Reverse Engineering

Abstract: The reverse engineering (RE) of electronic chips and systems can be used with honest and dishonest intentions. To inhibit RE for those with dishonest intentions (e.g., piracy and counterfeiting), it is important that the community is aware of the state-of-the-art capabilities available to attackers today. In this article, we will be presenting a survey of RE and anti-RE techniques on the chip, board, and system levels. We also highlight the current challenges and limitations of anti-RE and the research needed to overcome them. This survey should be of interest to both governmental and industrial bodies whose critical systems and intellectual property (IP) require protection from foreign enemies and counterfeiters who possess advanced RE capabilities.

Low-power filtering via adaptive error-cancellation

Abstract: A low-power technique for digital filtering referred to as adaptive error-cancellation (AEC) is presented in this paper. The AEC technique falls under the general class of algorithmic noise-tolerance (ANT) techniques proposed earlier for combating transient/soft errors. The proposed AEC technique exploits the correlation between the input and soft errors to estimate and cancel out the latter. In this paper, we apply AEC along with voltage overscaling (VOS), where the voltage is scaled beyond the minimum (referred to as V/sub dd-crit/) necessary for correct operation. We employ the AEC technique in the context of a frequency-division multiplexed (FDM) communication system and demonstrate that up to 71% energy reduction can be achieved over present-day voltage-scaled systems.

An energy-efficient leakage-tolerant dynamic circuit technique

Abstract: Technology scaling reduces device threshold voltages to mitigate speed loss due to scaled supply voltages. This, however, exponentially increases leakage power and adversely affects circuit reliability. In this paper, we investigate the performance degradation in high-leakage digital circuits. It is shown that deep submicron CMOS technologies lead to 60%-70% degradation in noise-immunity due to leakage. Dual-V/sub t/ domino designs mitigate the noise-immunity degradation to 30%-40% but inevitably lead to a loss of 20%-30% in circuit speed. To achieve a better noise-immunity vs. performance trade-off, a new dynamic circuit technique-the boosted-source (BS) technique is proposed. Simulation results of wide fan-in gates designed in the Predictive Berkeley BSIM3v3 0.13 /spl mu/m technology demonstrate 1.6X-3X improvement in noise-immunity at the expense of marginal energy overhead but no loss in delay, as compared with the existing circuit techniques.

31p-S-4 Giant Magnetoresistance in Magnetic Manganese Oxide with Intrinsic Antiferromagnetic Spin Structure

Abstract: Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.

Methods of Numerical Integration

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A 20 mV Input Boost Converter With Efficient Digital Control for Thermoelectric Energy Harvesting

Abstract: This paper presents a low power boost converter for thermoelectric energy harvesting that demonstrates an efficiency that is 15% higher than the state-of-the-art for voltage conversion ratios above 20. This is achieved by utilizing a technique allowing synchronous rectification in the discontinuous conduction mode. A low-power method for input voltage monitoring is presented. The low input voltage requirements allow operation from a thermoelectric generator powered by body heat. The converter, fabricated in a 0.13 μm CMOS process, operates from input voltages ranging from 20 mV to 250 mV while supplying a regulated 1 V output. The converter consumes 1.6 (1.1) μW of quiescent power, delivers up to 25 (175) μW of output power, and is 46 (75)% efficient for a 20 mV and 100 mV input, respectively.

Assessment of Microbial Fuel Cell Configurations and Power Densities

Abstract: Different microbial electrochemical technologies are being developed for many diverse applications, including wastewater treatment, biofuel production, water desalination, remote power sources, and biosensors. Current and energy densities will always be limited relative to batteries and chemical fuel cells, but these technologies have other advantages based on the self-sustaining nature of the microorganisms that can donate or accept electrons from an electrode, the range of fuels that can be used, and versatility in the chemicals that can be produced. The high cost of membranes will likely limit applications of microbial electrochemical technologies that might require a membrane. For microbial fuel cells, which do not need a membrane, questions about whether larger-scale systems can produce power densities similar to those obtained in laboratory-scale systems remain. It is shown here that configuration and fuel (pure chemicals in laboratory media vs actual wastewaters) remain the key factors in power pro...