Leakage-Aware Interconnect for On-Chip Network

On-chip networks have been proposed as the interconnect fabric for future systems-on-chip and multi-processors on chip. Power is one of the main constraints of these systems and interconnect consumes a significant portion of the power budget. In this paper, we propose four leakage-aware interconnect schemes. Our schemes achieve 10.13%~63.57% active leakage savings and 12.35%~95.96% standby leakage savings across schemes while the delay penalty ranges from 0% to 4.69%.Comment: Submitted on behalf of EDAA (http://www.edaa.com/

Energy macro-model for on chip interconnection buses

This report presents a fast method of evaluating the power consumption of a bus. Given an on-chip bus driver-interconnection-receiver design of N parallel lines,the objective is to develop its energy consumption macro-model. With this model we are be able to evaluate the energy metrics for the bus under a certain traffic and information coding.Peer Reviewe

High-Speed and Low-Energy On-Chip Communication Circuits.

Continuous technology scaling sharply reduces transistor delays, while fixed-length global wire delays have increased due to less wiring pitch with higher resistance and coupling capacitance. Due to this ever growing gap, long on-chip interconnects pose well-known latency, bandwidth, and energy challenges to high-performance VLSI systems. Repeaters effectively mitigate wire RC effects but do little to improve their energy costs. Moreover, the increased complexity and high level of integration requires higher wire densities, worsening crosstalk noise and power consumption of conventionally repeated interconnects. Such increasing concerns in global on-chip wires motivate circuits to improve wire performance and energy while reducing the number of repeaters. This work presents circuit techniques and investigation for high-performance and energy-efficient on-chip communication in the aspects of encoding, data compression, self-timed current injection, signal pre-emphasis, low-swing signaling, and technology mapping. The improved bus designs also consider the constraints of robust operation and performance/energy gains across process corners and design space. Measurement results from 5mm links on 65nm and 90nm prototype chips validate 2.5-3X improvement in energy-delay product.Ph.D.Electrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/75800/1/jseo_1.pd

Network-on-Chip

Addresses the Challenges Associated with System-on-Chip Integration Network-on-Chip: The Next Generation of System-on-Chip Integration examines the current issues restricting chip-on-chip communication efficiency, and explores Network-on-chip (NoC), a promising alternative that equips designers with the capability to produce a scalable, reusable, and high-performance communication backbone by allowing for the integration of a large number of cores on a single system-on-chip (SoC). This book provides a basic overview of topics associated with NoC-based design: communication infrastructure design, communication methodology, evaluation framework, and mapping of applications onto NoC. It details the design and evaluation of different proposed NoC structures, low-power techniques, signal integrity and reliability issues, application mapping, testing, and future trends. Utilizing examples of chips that have been implemented in industry and academia, this text presents the full architectural design of components verified through implementation in industrial CAD tools. It describes NoC research and developments, incorporates theoretical proofs strengthening the analysis procedures, and includes algorithms used in NoC design and synthesis. In addition, it considers other upcoming NoC issues, such as low-power NoC design, signal integrity issues, NoC testing, reconfiguration, synthesis, and 3-D NoC design. This text comprises 12 chapters and covers: The evolution of NoC from SoC—its research and developmental challenges NoC protocols, elaborating flow control, available network topologies, routing mechanisms, fault tolerance, quality-of-service support, and the design of network interfaces The router design strategies followed in NoCs The evaluation mechanism of NoC architectures The application mapping strategies followed in NoCs Low-power design techniques specifically followed in NoCs The signal integrity and reliability issues of NoC The details of NoC testing strategies reported so far The problem of synthesizing application-specific NoCs Reconfigurable NoC design issues Direction of future research and development in the field of NoC Network-on-Chip: The Next Generation of System-on-Chip Integration covers the basic topics, technology, and future trends relevant to NoC-based design, and can be used by engineers, students, and researchers and other industry professionals interested in computer architecture, embedded systems, and parallel/distributed systems

Modeling and Analysis of Noise and Interconnects for On-Chip Communication Link Design

This thesis considers modeling and analysis of noise and interconnects in onchip communication. Besides transistor count and speed, the capabilities of a modern design are often limited by on-chip communication links. These links typically consist of multiple interconnects that run parallel to each other for long distances between functional or memory blocks. Due to the scaling of technology, the interconnects have considerable electrical parasitics that affect their performance, power dissipation and signal integrity. Furthermore, because of electromagnetic coupling, the interconnects in the link need to be considered as an interacting group instead of as isolated signal paths. There is a need for accurate and computationally effective models in the early stages of the chip design process to assess or optimize issues affecting these interconnects. For this purpose, a set of analytical models is developed for on-chip data links in this thesis. First, a model is proposed for modeling crosstalk and intersymbol interference. The model takes into account the effects of inductance, initial states and bit sequences. Intersymbol interference is shown to affect crosstalk voltage and propagation delay depending on bus throughput and the amount of inductance. Next, a model is proposed for the switching current of a coupled bus. The model is combined with an existing model to evaluate power supply noise. The model is then applied to reduce both functional crosstalk and power supply noise caused by a bus as a trade-off with time. The proposed reduction method is shown to be effective in reducing long-range crosstalk noise. The effects of process variation on encoded signaling are then modeled. In encoded signaling, the input signals to a bus are encoded using additional signaling circuitry. The proposed model includes variation in both the signaling circuitry and in the wires to calculate the total delay variation of a bus. The model is applied to study level-encoded dual-rail and 1-of-4 signaling. In addition to regular voltage-mode and encoded voltage-mode signaling, current-mode signaling is a promising technique for global communication. A model for energy dissipation in RLC current-mode signaling is proposed in the thesis. The energy is derived separately for the driver, wire and receiver termination.Siirretty Doriast

DETC2011-48912 A JOINT-CODING SCHEME WITH CROSSTALK AVOIDANCE

ABSTRACT The reliable transfer in Network on Chip can be guaranteed by crosstalk avoidance and error detection code. In this paper, we propose a joint coding scheme combined with crosstalk avoidance coding with error control coding. The Fibonacci numeral system is applied to satisfy the requirement of crosstalk avoidance coding, and the error detection is achieved by adding parity bits. We also implement the codec in register transfer level. Furthermore, the schemes of codec applying to fault-tolerant router are analyzed. The experimental result shows that "once encode, multiple decode" scheme outperforms other schemes in trade-off of delay, area and power

Low-power and high-fanout bus design techniques

Low-power techniques pose an important concern, when designing autonomous electronic devices. Most of the upcoming applications increasingly demand high performance and low-power consumption. In this thesis work, two low-power and high-fanout bus design techniques are reviewed. Pulse Width Modulation (PWM) and Time-Domain Conversion (TDC) approaches are elucidated. Schematic simulations (Cadence), quantitative and comparative results of both approaches are included. Additionally, on-chip wire theory is shown as well as some optimized bus simulation models (MATLAB), concluding with a summary of the main application areas for this techniques. Finally , two ready-to-use library cells are generated, as well as Verilog code for the TDC system

Power-efficient memory bus encoding using stride-based stream reconstruction

With the rapid increase in the complexity of chips and the popularity of portable devices, the performance demand is not any more the only important constraint in the embedded system. In stead, energy consumption has become one of the main design issues for contemporary embedded systems, especially for I/O interface due to the high capacitance of bus transition. In this paper, we propose a bus encoding scheme, which may reduce transitions by reconstructing active address streams with variable cached strides. The key idea is to obtain the variable strides for dierent sets of active addressing streams such that the decoder reconstructs these interlaced streams with these strides. Instead of sending the full address, the encoder may only send partial ad- dress or stride by using either one-hot or binary-inversion encoding. To exploit the locality and dynamically adjust the value of stride of active address streams, we partially compare the previous addresses of existing streams with the current address. Hence, the data transmitted on the bus can be minimally encoded. Experiments with several MediaBench benchmarks show that the scheme can achieve an average of 60% reduction in bus switching activity.Facultad de Informátic