Low Power Processor Architectures and Contemporary Techniques for Power Optimization – A Review

The technological evolution has increased the number of transistors for a given die area significantly and increased the switching speed from few MHz to GHz range. Such inversely proportional decline in size and boost in performance consequently demands shrinking of supply voltage and effective power dissipation in chips with millions of transistors. This has triggered substantial amount of research in power reduction techniques into almost every aspect of the chip and particularly the processor cores contained in the chip. This paper presents an overview of techniques for achieving the power efficiency mainly at the processor core level but also visits related domains such as buses and memories. There are various processor parameters and features such as supply voltage, clock frequency, cache and pipelining which can be optimized to reduce the power consumption of the processor. This paper discusses various ways in which these parameters can be optimized. Also, emerging power efficient processor architectures are overviewed and research activities are discussed which should help reader identify how these factors in a processor contribute to power consumption. Some of these concepts have been already established whereas others are still active research areas. © 2009 ACADEMY PUBLISHER

An FPGA Architecture and CAD Flow Supporting Dynamically Controlled Power Gating

© 2015 IEEE.Leakage power is an important component of the total power consumption in field-programmable gate arrays (FPGAs) built using 90-nm and smaller technology nodes. Power gating was shown to be effective at reducing the leakage power. Previous techniques focus on turning OFF unused FPGA resources at configuration time; the benefit of this approach depends on resource utilization. In this paper, we present an FPGA architecture that enables dynamically controlled power gating, in which FPGA resources can be selectively powered down at run-time. This could lead to significant overall energy savings for applications having modules with long idle times. We also present a CAD flow that can be used to map applications to the proposed architecture. We study the area and power tradeoffs by varying the different FPGA architecture parameters and power gating granularity. The proposed CAD flow is used to map a set of benchmark circuits that have multiple power-gated modules to the proposed architecture. Power savings of up to 83% are achievable for these circuits. Finally, we study a control system of a robot that is used in endoscopy. Using the proposed architecture combined with clock gating results in up to 19% energy savings in this application

dRail: a novel physical layout methodology for power gated circuits

In this paper we present a physical layout methodology, called dRail, to allow power gated and non-power gated cells to be placed next to each other. This is unlike traditional voltage area layout which separates cells to prevent shorting of power supplies leading to impact on area, routing and power. To implement dRail, a modified standard cell architecture and physical layout is proposed. The methodology is validated by implementing power gating on the data engine in an ARM Cortex-A5 processor using a 65nm library, and shows up to 38% reduction in area cost when compared to traditional voltage area layou