This paper describes Glitchless, a circuit-level technique for reducing power in FPGAs by eliminating unnecessary logic transitions called glitches. This is done by adding programmable delay elements to the logic blocks of the FPGA. After routing a circuit and performing static timing analysis, these delay elements are programmed to align the arrival times of the inputs of each LUT, thereby preventing new glitches from being generated. Moreover, the delay elements also behave as filters that eliminate other glitches generated by upstream logic or off-chip circuitry. On average, the proposed implementation eliminates 87 % of the glitching, which reduces overall FPGA power by 17%. The added circuitry increases the overall FPGA area by 6 % and critical-path delay by less than 1%. Furthermore, since it is applied after routing, the proposed technique requires little or no modifications to the routing architecture or CAD flow.

As feature sizes scale toward atomic limits, parameter variation continues to increase, leading to increased margins in both delay and energy. The possibility of very slow devices on critical paths forces designers to increase transistor sizes, reduce clock speed and operate at higher voltages than desired in order to meet timing. With post-fabrication configurability, FPGAs have the opportunity to use slow devices on non-critical paths while selecting fast devices for critical paths. To understand the potential benefit we might gain from component-specific mapping, we quantify the margins associated with parameter variation in FPGAs over a wide range of predictive technologies (45nm–12nm) and gate sizes and show how these margins can be significantly reduced by delay-aware, component-specific routing. For the Toronto 20 benchmark set, we show that component-specific routing can eliminate delay margins induced by variation and reduce energy for energy minimal designs by 1.42–1.98×. We further show that these benefits increase as technology scales.

Abstract not found

Abstract—Reliability, power consumption and timing performance are key considerations for the utilisation of fieldprogrammable gate arrays. Online measurement techniques can determine the timing characteristics of an FPGA application while it is operating, and facilitate a range of benefits. Degradation can be monitored by tracking changes in timing performance, while power consumption can be reduced through dynamic voltage scaling (DVS) of the power supply to exploit any spare timing headroom. If higher performance is the objective, dynamic frequency scaling (DFS) can be used to maximise operating frequency. In both cases, online timing measurement of the application circuit is used to exploit favourable operating conditions. This work demonstrates a method of online measurement, achieved by sweeping the phase of a secondary clock signal, driving additional shadowing registers strategically added to the application design. The measurement technique and initial voltage and frequency scaling experiments are demonstrated on an Altera Cyclone III FPGA. Timing performance can be measured with a best case resolution of 96ps. The additional circuitry results in minimal overhead in terms of area and performance. Power savings of 23 % dynamic and 13 % static in an example circuit are achieved through DVS, or performance improvements of 21 % through DFS, when compared with operating at nominal core voltage, or timing model FMAX. I.

The paper presents an overview of a major research project on dependable embedded systems that has started in Fall 2010 and is running for a projected duration of six years. Aim is a ‘dependability co-design ’ that spans various levels of abstraction in the design process of embedded systems starting from gate level through operating system, applications software to system architecture. In addition, we present a new classification on faults, errors, and failures.

A biological organism’s ability to sense and adapt to its environment is essential to its survival. Likewise, environmentally aware computing systems avail themselves to a longer operational life and a wider range of applications than traditional systems. In this paper, we propose a novel circuit design methodology that allows parameterizable hardware to self-regulate its temperature. We apply this methodology to an image recognition system on an Xilinx Virtex 4 FX100 field programmable gate array (FPGA). The image recognition system sustains a safe operational temperature by automatically adjusting its frequency and output quality. The circuit sacrifices output performance and quality to lower its internal temperature as the ambient temperature increases, and can leverage cooler temperatures by increasing output performance and quality. Furthermore, the circuit will shutdown if the ambient temperature becomes too hot for the device to function properly. A performance evaluation of our adaptive circuit under various thermal conditions shows up to a 4x factor increase in performance and a 2x factor increase in quality over a system without dynamic thermal control. 1.

This paper presents a DVS (Dynamic Voltage Scaling) enabled SoC (System-on-Chip) processing platform based on the Leon3 open-source processor and dynamically reconfigurable clock synthesis technology available in Virtex-4 Xilinx FPGAs. A special DVS monitor unit maintains correct operation of the processor core at a given voltage by tracking the behavior of an internal delay line and stopping the processor clock through a digital clock manager (DCM) macroblock when a timing error is about to occur. Upon detection of a new valid working point the DVS monitor unit reconfigures the main DCM to synthesize a new frequency-adjusted CPU clock signal and reactivates the processor. The energy savings and operation range of the technology are evaluated in the context of video coding applications by executing different motion estimation kernels. 1.

Reconfigurable circuits running in Field Programmable Gate Arrays (FPGAs) can be dynamically optimized for power based on computational requirements and thermal conditions of the environment. In the past, FPGA circuits were typically small and operated at a low frequency. Few users were concerned about high-power consumption and the heat generated by FPGA devices. The current generation of FPGAs, however, use extensive pipelining techniques to achieve high data processing rates and dense layouts that can generate significant amounts of heat. FPGA circuits can be synthesized that can generate more heat than the package can dissipate. For FPGAs that operate in controlled environments, heatsinks and fans can be mounted to the device to extract heat from the device. When FPGA devices do not operate in a controlled environment, however, changes to ambient temperature due to factors such as the failure of a fan or a reconfiguration of bitfile running on the device can drastically change the operating conditions. A protection mechanism is needed to ensure the proper operation of the FPGA circuits when such a change occurs. To address these issues, we have devised a reconfigurable temperature monitoring system that gives feedback to the FPGA circuit using the measured junction temperature of the device. Using this feedback, we designed a novel dual frequency switching system that allows the FPGA circuits to maintain the highest level of performance for a given maximum junction temperature. Our working system has been implemented and deployed on the Field Programmable Port Extender (FPX) platform at Washington University in St. Louis. Our experimental results with a scalable image correlation circuit show up to a 2.4x factor increase in performance as compared to a system withou...

This paper explores a vision of the design process in which components can optimize and verify themselves to improve efficiency, re-use, and confidence in correctness – the three design challenges identified by the International Technology Roadmap for Semiconductors. We illustrate what would take place for selfoptimization and self-verification before and after deployment of the design, and present the benefits and challenges for the proposed approach. 1.

iii As feature sizes scale toward atomic limits, parameter variation continues to increase, leading to increased margins in both delay and energy. Parameter variation both slows down devices and causes devices to fail. For applications that require high performance, the possibility of very slow devices on critical paths forces designers to reduce clock speed in order to meet timing. For an important and emerging class of applications that target energy-minimal operation at the cost of delay, the impact of variation-induced defects at very low voltages mandates the sizing up of transistors and operation at higher voltages to maintain functionality. With post-fabrication configurability, FPGAs have the opportunity to self-measure the impact of variation, determining the speed and functionality of each individual resource. Given that informa-tion, a delay-aware router can use slow devices on non-critical paths, fast devices on critical paths, and avoid known defects. By mapping each component individually and customizing designs to a component’s unique physical characteristics, we demonstrate that we can eliminate delay margins and reduce energy margins caused by variation.