Closed form metrics to accurately model the response in general arbitrarily-coupled RC trees.

Closed form expressions are presented for the first and second moment of the impulse response for arbitrarily-coupled RC trees with multiple drivers, and used to generate accurate second order estimations of the transfer function from any driver to the receiver. The superposition of the waveforms for all switching events allows precise delay and noise calculations for systems of coupled interconnects with different aggressor arrival times, with a minimum of computational complexity

Repeater insertion to minimise delay in coupled interconnects.

Signalling over long interconnect is a dominant issue in electronic chip design in current technologies, with the device sizes getting smaller and smaller and the circuits becoming ever larger. Repeater insertion is a well established technique to minimise the propagation delay over long resistive interconnect. In deep sub-micron technologies, as the wires are spaced closer and closer together and signal rise and fall times go into the sub-nano second region, the coupling between interconnects assumes great significance. The resulting crosstalk has implications on the data throughput and on signal integrity. Depending on the data correlation on the coupled lines, the delay can either decrease or increase. In this paper we attempt to quantify the effect of worst-case capacitive crosstalk in parallel buses and look at how it affects repeater insertion in particular. We develop analytic expressions for the delay, buffer size and number that are suitable in a-priori timing analyses and signal integrity estimations. All equations are checked against a dynamic circuit simulator (SPECTRE

On dynamic delay and repeater insertion.

In deep sub-micron technologies, as the wires are placed ever closer and signal rise and fall times go into the sub-nano second region, increased crosstalk has implications on the data throughput and on signal integrity. Depending on the data correlation on the coupled lines, the delay can either decrease or increase. Here we show that in uniform coupled lines, the response for several important switching configurations has a dominant pole characteristic. This allows easy prediction for the average, worst-case and best-case delay of buffered lines. We show that the repeater numbering and sizing can be optimised to deal with crosstalk under different constraints to best match the application. Area and power issues are considered and all equations are checked against a dynamic circuit simulator (SPECTRE)

Optimising bandwidth over deep sub-micron interconnect.

In deep sub-micron (DSM) circuits proper analysis of interconnect delay is very important. When relatively long wires are placed in parallel, it is essential to include the effects of cross-talk on delay. In a parallel wire structure, the exact spacing and size of the wires determine both the resistance and the distribution of the capacitance between the ground plane and the adjacent signal carrying conductors, and have a direct effect on the delay. Repeater insertion depending on whether it is optimal or constrained, affects the delay in different ways. Considering all these effects we show that there is a clear optimum configuration for the wires which maximises the total bandwidth. Our analysis is valid for lossy interconnects as are typical of wires in DSM technologies

Accurate a priori signal integrity estimation using a multilevel dynamic interconnect model for deep submicron VLSI design.

A multilevel dynamic interconnect model was derived for accurate a priori signal integrity estimates. Cross-talk and delay estimations over interconnects in deep submicron technology were analyzed systematically using this model. Good accuracy and excellent time-efficiency were found compared with electromagnetic simulations. We aim to build a dynamic interconnect library with this model to facilitate the interconnect issues for future VLSI design

On signalling over through-silicon via (TSV) interconnects in 3-D integrated circuits.

This paper discusses signal integrity (SI) issues and signalling techniques for Through Silicon Via (TSV) interconnects in 3-D Integrated Circuits (ICs). Field-solver extracted parasitics of TSVs have been employed in Spice simulations to investigate the effect of each parasitic component on performance metrics such as delay and crosstalk and identify a reduced-order electrical model that captures all relevant effects. We show that in dense TSV structures voltage-mode (VM) signalling does not lend itself to achieving high data-rates, and that current-mode (CM) signalling is more effective for high throughput signalling as well as jitter reduction. Data rates, energy consumption and coupled noise for the different signalling modes are extracted

Extending systems-on-chip to the third dimension : performance, cost and technological tradeoffs.

Because of the today's market demand for high-performance, high-density portable hand-held applications, electronic system design technology has shifted the focus from 2-D planar SoC single-chip solutions to different alternative options as tiled silicon and single-level embedded modules as well as 3-D integration. Among the various choices, finding an optimal solution for system implementation dealt usually with cost, performance and other technological trade-off analysis at the system conceptual level. It has been identified that the decisions made within the first 20% of the total design cycle time will ultimately result up to 80% of the final product cost. In this paper, we discuss appropriate and realistic metric for performance and cost trade-off analysis both at system conceptual level (up-front in the design phase) and at implementation phase for verification in the three-dimensional integration. In order to validate the methodology, two ubiquitous electronic systems are analyzed under various implementation schemes and discuss the pros and cons of each of them

A global wire planning scheme for Network-on-Chip.

As technology scales down, the interconnect for on-chip global communication becomes the delay bottleneck. In order to provide well-controlled global wire delay and efficient global communication, a packet switched Network-on-Chip (NoC) architecture was proposed by different authors. In this paper, the NoC system parameters constrained by the interconnections are studied. Predictions on scaled system parameters such as clock frequency, resource size, global communication bandwidth and inter-resource delay are made for future technologies. Based on these parameters, a global wire planning scheme is proposed

Memory technology for extended large-scale integration in future electronics applications.

Extending 2-D planar topologies in integrated circuits (ICs) to a 3-D implementation has the obvious benefits of reducing the overall footprint and average interconnection length, with associated improvements in cost, and delay and energy consumption, while also providing an opportunity to integrate disparate technologies. Such advances are very much technology driven, and early research into 3-D integration has now crystallised into commercially viable options that are being pursued by many companies. Being able to position memory in closer proximity to processing elements in a NoC architecture as afforded by a 3-D physical architecture has the potential to improve the memory bandwidth and mitigate the general nature of delay constrained performance in IC design. Understanding the nature of the opportunities and constraints provided in such a 3-D physical architecture is crucial in realising the true benefits of 3-D integration in future applications

Maximizing throughput over parallel wire structures in the deep submicrometer regime.

In a parallel multiwire structure, the exact spacing and size of the wires determine both the resistance and the distribution of the capacitance between the ground plane and the adjacent signal carrying conductors, and have a direct effect on the delay. Using closed-form equations that map the geometry to the wire parasitics and empirical switch factor based delay models that show how repeaters can be optimized to compensate for dynamic effects, we devise a method of analysis for optimizing throughput over a given metal area. This analysis is used to show that there is a clear optimum configuration for the wires which maximizes the total bandwidth. Additionally, closed form equations are derived, the roots of which give close to optimal solutions. It is shown that for wide buses, the optimal wire width and spacing are independent of the total width of the bus, allowing easy optimization of on-chip buses. Our analysis and results are valid for lossy interconnects as are typical of wires in submicron technologies