Performance Optimization Under the Transmission Line Model

• Main Authors: Tai-Chen Chen, 陳泰蓁
• Other Authors: Yao-Wen Chang
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/82510908347426425020

碩士 === 國立交通大學 === 資訊科學系 === 89 === Transmission line effects are very important for the timing estimation and optimization in high-performance circuits. Most previous works on transmission lines are based on relatively complicated models, resulting in higher time complexity. We present a simple, yet accurate formula for the delay computation under the lossless and lossy transmission line models. Extensive simulations with SPICE show that the formula has high fidelity, with an average error rate of within 6.85% (1.50%) for a lossy (lossless) transmission line. Based on this formula, we show the property that the minimum delay for a lossy transmission line with reflections occurs when the number of round trips equals one. Besides, we show that the delay (with the consideration of fringing capacitance) of a circuit path is a posynomial function (i.e., convex function) in wire and buffer sizes, implying that a local optimum is equal to the global optimum. Thus we can apply any efficient search algorithm, such as the well-known gradient search procedure, to compute the optimal wire and buffer sizes for timing optimization for a circuit path. Experimental results show that simultaneous wire and buffer sizing is very effective in minimizing the delay of circuit paths under the transmission line model.