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Solve design problems with signal integrity optimization: optimization routines save time by using automated methods to determine if performance goals are met.

Article Excerpt
Printed circuit board (PCB) design often begins with the development of signal integrity (SI) guidelines to ensure adequate performance of the final product. Most often the guidelines are based on traditional engineering practices through manual manipulation of circuit parameters and judicious interpretation of results. While such approaches do result in useful conclusions, they can also consume significant effort, only to reach sub-optimal conclusions. Alternatively, optimization routines can be used to aid in SI analysis and the development of PCB design guidelines.

Optimization routines have been well proven to aid analysis across a variety of common tasks, such as determining the optimal values for circuit parameters. In addition, there are several non-traditional applications where optimization can be useful, such as developing application-specific termination schemes.

With increasingly higher speeds and routing densities, proper signal integrity (SI) engineering is an important aspect of printed circuit board (PCB) design. At its basic levels, SI engineering involves the development of design guidelines for impedance control, termination, attenuation, and isolation. As design complexity increases, so does the associated SI analysis.

Where feasible, common industry practice (i.e., rules of thumb) can guide SI analysis on many issues with good results. In situations where more significant analysis is necessary, SI engineers can potentially benefit from non-traditional approaches. Optimization routines are engineering tools that are often useful in these situations, as they automate the process of tuning parametric values to achieve desired performance.

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One of the more common applications of optimization routines is the development of equivalent-circuit models (1,2) of various passive interconnect. In these cases, the interconnect performance is measured in the lab in either time or frequency domains. Based on the measured performance and knowledge of the physical structure, a circuit topology is generated to approximate the performance. Optimization is then used to adjust the various circuit element values to best approximate the measured performance. In addition to...

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