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Method for Smart Miller Capacitance Factor

IP.com Disclosure Number: IPCOM000008678D
Publication Date: 2002-Jul-02
Document File: 4 page(s) / 114K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for Smart Miller Capacitance Factor (SMCF). Benefits include improved results accuracy and improved designer productivity

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Method for Smart Miller Capacitance Factor

Disclosed is a method for Smart Miller Capacitance Factor (SMCF). Benefits include improved results accuracy and improved designer productivity.

Background

              In Deep Sub-Micron (DSM) technology, capacitive cross-coupling becomes a major factor influencing the delay in very large-scale integration (VLSI) interconnection. Cross-coupling interference (cross-talk) occurs among interconnect wires on the VLSI chip. As a result, wires influence the delay of signals and shape each other’s waves.

              For analysis purposes, a net under analysis is called a victim, while other nets impacting it are called aggressors. In addition to accurately simulating several wires to determine their reciprocal influences, standard practice analyzes the victim, while decoupling the aggressors and modeling their capacitances, which is designated as Ci. The aggressors are grounded and have the value Ci*MCF, where the MCF reflects an increase or decrease in the effective capacitance of the victim.

              For example, ground capacitors are conventionally calculated using MCF, initial ground, and cross capacitance on each victim node: Ci= Cgi + MCF*Cci .

              Extensive studies in both industry and academia cover the relationship between the wave and slope on the aggressors and the induced crosstalk noise on the victim. Fewer studies exist on MCF estimation or attempt to provide a good-accuracy formula for it.

General description

              The disclosed method is an empiric formula based on slope ratio that satisfies the case of MCF=2 for equal victim and aggressors slope and provides more accurate formulas for R=Slope(victim)/ Slope(aggressor).

              The formula MCF= R is very inaccurate. Attempts at polynomial functions of R does not provide good accuracy. The disclosed formula can be fitted and tuned to typical structures in a chip or large-statistical sample of interconnects and applied with a good statistical fit to simulated results.

              The disclosed formula, called SMCF, is:

 


Advantages

              The disclosed method provides advantages, including:

·        Improved accuracy in determining MCF, reducing the amount of over-design that occurs

·        Improved designer productivity due to the improved calculation time compared to the amount of time required for simulation

Detailed description

              The disclosed method is an accurate empirical formula for cross-talk MCF estimation in VLSI. For example, two lines are cross-coupled via capacitors (see Figure 1). ...