RC delay metrics for performance optimization
RC delay metrics for performance optimization
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用于性能优化的 RC 延迟指标
DOI：
10.1109/43.920682
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Chandramouli V. Kashyap
中科院分区：
文献类型：
--
作者：
C. Alpert;A. Devgan;Chandramouli V. Kashyap
对于诸如布局规划、布局、缓冲器插入、布线尺寸和全局布线等性能优化任务，Elmore 电阻电容 (RC) 延迟度量由于其简单的封闭形式表达式、快速的计算速度和仿真保真度而仍然很受欢迎。更准确的延迟计算方法通常是中央处理单元密集型的和/或难以实现。为了弥补准确性和效率/简单性之间的差距，我们提出了两种新的 RC 延迟指标，称为两矩延迟 (D2M) 和有效电容指标 (ECM)，它们实际上与 Elmore 指标一样简单和快速，但更准确。 D2M 在一个简单的公式中使用脉冲响应的两个矩，该公式在 RC 线的远端具有高精度。 ECM 通过“有效电容”对下游电容进行建模来捕获电阻屏蔽效应。相比之下，埃尔莫尔度量将其建模为集总电容，从而忽略了电阻屏蔽。虽然 ECM 不如 D2M 准确，但它能产生一致的性能，并且由于其类似 Elmore 的递归结构，可能非常适合优化。
For performance optimization tasks such as floorplanning, placement, buffer insertion, wire sizing, and global routing, the Elmore resistance-capacitance (RC) delay metric remains popular due to its simple closed form expression, fast computation speed, and fidelity with respect to simulation. More accurate delay computation methods are typically central processing unit intensive and/or difficult to implement. To bridge this gap between accuracy and efficiency/simplicity, we propose two new RC delay metrics called delay via two moments (D2M) and effective capacitance metric (ECM), which are virtually as simple and fast as the Elmore metric, but more accurate. D2M uses two moments of the impulse response in a simple formula that has high accuracy at the far end of RC lines. ECM captures resistive shielding effects by modeling the downstream capacitance by an "effective capacitance." In contrast, the Elmore metric models this as a lumped capacitance, thereby ignoring resistive shielding. Although not as accurate as D2M, ECM yields consistent performance and may be well-suited to optimization due to its Elmore-like recursive construction.