Articles by Bert Simonovich

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A Guide for Single-Ended to Mixed-Mode S-parameter Conversions

Signal integrity engineers almost always have to work with S-parameters. If you have not had to work with them yet, then chances are you will sometime in your career. As speed moves up in the double-digit GB/s regime, many industry standards are moving to serial link-based architectures and are using frequency domain compliance limits based on S-parameter measurements.


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What Happens When Stripline Signals Cross Split Power Planes

Many claim that for stripline, it is ok to cross a split power plane, so long as the other adjacent reference plane is solid. Some others claim if there is an adjacent solid reference plane, less than 5mils away under the split, crosstalk will be mitigated. Read on to see an investigation into what really happens when stripline signals cross split power planes.


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A Causal Conductor Roughness Model and its Effect on Transmission Line Characteristics

In the GB/s regime, accurate modeling of insertion loss and phase delay is a precursor to successful high-speed serial link designs. We propose a causal (physically meaningful) form of the Hammerstad and Cannonball-Huray metal roughness frequency dependent complex correction factor. Compared to the widely used, non-causal form, it considerably increases the inductive component of internal metal impedance. Transmission lines simulated with a causal version demonstrate increased phase delay and characteristic impedance. By obtaining the dielectric and roughness parameters solely from manufacturers' data sheets, we validate the model through a detailed case study to test its accuracy.


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