Crosstalk aware coupled line delay tree construction for on-chip interconnects.
ABSTRACT Crosstalk noise dominates in deep submicron VLSI design as interconnects are more closely placed over a small layout area. Signal response and signal integrity is largely affected by crosstalk delay and noise. In this paper, we propose a coupled line delay model for on-chip interconnects during global routing, with crosstalk between wires as the parameter to be optimized. Our proposed model is influenced by moment matching model of a transmission line. We propose an algorithm for crosstalk aware delay tree construction, optimizing the effect of crosstalk delay in the tree structure by employing a cut and join strategy. Experiments are done on some benchmark instances with different technology parameters, and simulation results obtained are quite encouraging.
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Conference Paper: Revisiting fidelity: a case of elmore-based Y-routing trees.[Show abstract] [Hide abstract]
ABSTRACT: The dominance of interconnect delay in VLSI circuit de- sign is well-known. Construction of routing trees in recent times has to take care of the timing issues for faster design convergence. Thus there is immense scope of research in design and performance of interconnects. Our current work encompasses two aspects of this research. On one hand, we consider the construction of cost-effective global routing trees with the recently introduced Y -interconnects, and on the other hand, we utilize this framework for verifying the supremacy of the Elmore delay estimate for its high fidelity. In order to ensure accurate computation of fidelity, (i) we propose new statistically proven formulae for fidelity, and (ii) compute the fidelity values based on delay estimates for optimal and near-optimal trees. Our experiments on sev- eral randomly generated problem instances and benchmarks confirm once again the supremacy of fidelity of Elmore delay over that of linear delay.The Tenth International Workshop on System-Level Interconnect Prediction (SLIP 2008), Newcastle, UK, April 5-8, 2008, Proceedings; 01/2008
Conference Paper: Crosstalk analysis in nanometer technologies.[Show abstract] [Hide abstract]
ABSTRACT: Process variations have become a key concern of circuit designers because of their significant, yet hard to predict impact on performance and signal integrity of VLSI circuits. Statistical approaches have been suggested as the most effective substitute for corner-based approaches to deal with the variability of present process technology nodes. This paper introduces a statistical analysis of the crosstalk-aware delay of coupled interconnects considering process variations. The few existing works that have studied this problem suffer not only from shortcomings in their statistical models, but also from inaccurate crosstalk circuit models. We utilize an accurate distributed RC-π model of the interconnections to be able to model process variations close to reality. The considerable effect of correlation among the parameters of neighboring wire segments is also indicated. Statistical properties of the crosstalk-aware output delay are characterized and presented as closed-formed expressions. Monte Carlo Spice-based experimental results demonstrate the effectiveness of the proposed approach in accurately modeling the correlation-aware process variations and their impact on interconnect delay when crosstalk is present.Proceedings of the 16th ACM Great Lakes Symposium on VLSI 2006, Philadelphia, PA, USA, April 30 - May 1, 2006; 01/2006
Conference Paper: Buffer Insertion for Noise and Delay Optimization.[Show abstract] [Hide abstract]
ABSTRACT: Interconnect-driven optimization is an increasingly important step in high-performance design. Algorithms for buffer insertion have been successfully utilized to reduce delay in global interconnect paths; however, existing techniques only optimize delay and timing slack, With the continually increasing ratio of coupling capacitance to total capacitance and the use of aggressive dynamic logic circuit families, noise analysis and avoidance is becoming a major design bottleneck. Hence, timing and noise must be simultaneously optimized to achieve maximum performance. This paper presents comprehensive buffer insertion techniques for noise and delay optimization. Three algorithms are presented, the first for noise avoidance for single sink trees, the second for avoidance for multiple sink trees, and the last for simultaneous noise and delay optimization. We prove the optimality of each algorithm (under various assumptions) and present other theoretical results as well. We ran experiments on a high-performance microprocessor design and show that our approach fixes all noise violations, Our approach was separately verified by a detailed, simulation-based noise analysis tool. Further, we show that optimizing delay alone cannot fix all of the noise violations and that the performance penalty induced by optimizing both delay and noise as opposed to only delay is less than 2%Design Automation Conference, 1998. Proceedings; 01/1998