Kaushik Roy

Bio: Kaushik Roy is an academic researcher from Purdue University. The author has contributed to research in topics: CMOS & Logic gate. The author has an hindex of 97, co-authored 1402 publications receiving 42661 citations. Previous affiliations of Kaushik Roy include Texas Instruments & IBM.

Leakage current mechanisms and leakage reduction techniques in deep-submicrometer CMOS circuits

Abstract: High leakage current in deep-submicrometer regimes is becoming a significant contributor to power dissipation of CMOS circuits as threshold voltage, channel length, and gate oxide thickness are reduced. Consequently, the identification and modeling of different leakage components is very important for estimation and reduction of leakage power, especially for low-power applications. This paper reviews various transistor intrinsic leakage mechanisms, including weak inversion, drain-induced barrier lowering, gate-induced drain leakage, and gate oxide tunneling. Channel engineering techniques including retrograde well and halo doping are explained as means to manage short-channel effects for continuous scaling of CMOS devices. Finally, the paper explores different circuit techniques to reduce the leakage power consumption.

Towards spike-based machine intelligence with neuromorphic computing.

Abstract: Guided by brain-like ‘spiking’ computational frameworks, neuromorphic computing—brain-inspired computing for machine intelligence—promises to realize artificial intelligence while reducing the energy requirements of computing platforms. This interdisciplinary field began with the implementation of silicon circuits for biological neural routines, but has evolved to encompass the hardware implementation of algorithms with spike-based encoding and event-driven representations. Here we provide an overview of the developments in neuromorphic computing for both algorithms and hardware and highlight the fundamentals of learning and hardware frameworks. We discuss the main challenges and the future prospects of neuromorphic computing, with emphasis on algorithm–hardware codesign. The authors review the advantages and future prospects of neuromorphic computing, a multidisciplinary engineering concept for energy-efficient artificial intelligence with brain-inspired functionality.

Gated-V/sub dd/: a circuit technique to reduce leakage in deep-submicron cache memories

Abstract: Deep-submicron CMOS designs have resulted in large leakage energy dissipation in microprocessors. While SRAM cells in on-chip cache memories always contribute to this leakage, there is a large variability in active cell usage both within and across applications. This paper explores an integrated architectural and circuit-level approach to reducing leakage energy dissipation in instruction caches. We propose, gated-V/sub dd/, a circuit-level technique to gate the supply voltage and reduce leakage in unused SRAM cells. Our results indicate that gated-V/sub dd/ together with a novel resizable cache architecture reduces energy-delay by 62% with minimal impact on performance.

Low-Power Digital Signal Processing Using Approximate Adders

Abstract: Low power is an imperative requirement for portable multimedia devices employing various signal processing algorithms and architectures. In most multimedia applications, human beings can gather useful information from slightly erroneous outputs. Therefore, we do not need to produce exactly correct numerical outputs. Previous research in this context exploits error resiliency primarily through voltage overscaling, utilizing algorithmic and architectural techniques to mitigate the resulting errors. In this paper, we propose logic complexity reduction at the transistor level as an alternative approach to take advantage of the relaxation of numerical accuracy. We demonstrate this concept by proposing various imprecise or approximate full adder cells with reduced complexity at the transistor level, and utilize them to design approximate multi-bit adders. In addition to the inherent reduction in switched capacitance, our techniques result in significantly shorter critical paths, enabling voltage scaling. We design architectures for video and image compression algorithms using the proposed approximate arithmetic units and evaluate them to demonstrate the efficacy of our approach. We also derive simple mathematical models for error and power consumption of these approximate adders. Furthermore, we demonstrate the utility of these approximate adders in two digital signal processing architectures (discrete cosine transform and finite impulse response filter) with specific quality constraints. Simulation results indicate up to 69% power savings using the proposed approximate adders, when compared to existing implementations using accurate adders.

Low power CMOS VLSI circuit design

Abstract: Low--Power CMOS VLSI Design. Physics of Power Dissipation in CMOS FET Devices. Power Estimation. Synthesis for Low Power. Design and Test of Low--Voltage CMOS Circuits. Low--Power Static Ram Architectures. Low--Energy Computing Using Energy Recovery Techniques. Software Design for Low Power. Index.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Leakage current mechanisms and leakage reduction techniques in deep-submicrometer CMOS circuits

Abstract: High leakage current in deep-submicrometer regimes is becoming a significant contributor to power dissipation of CMOS circuits as threshold voltage, channel length, and gate oxide thickness are reduced. Consequently, the identification and modeling of different leakage components is very important for estimation and reduction of leakage power, especially for low-power applications. This paper reviews various transistor intrinsic leakage mechanisms, including weak inversion, drain-induced barrier lowering, gate-induced drain leakage, and gate oxide tunneling. Channel engineering techniques including retrograde well and halo doping are explained as means to manage short-channel effects for continuous scaling of CMOS devices. Finally, the paper explores different circuit techniques to reduce the leakage power consumption.