Articles by Bert Simonovich

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Stackup Beware: Case Study of the Effects on Transmission Line Losses Due to Mixed Reference Plane Roughness

Designing the right PCB stackup can make or break product performance. If the product has circuitry that is impedance and transmission loss sensitive, then paying attention to conductor surface roughness is paramount. Sometimes, however, the roughness of adjacent reference plane(s) is overlooked. If the adjacent high-speed signal layer uses smoother copper than one or both reference planes, a higher insertion loss than expected for that layer will occur and possibly cause a product to fail compliance. So, how is this determined before finalizing the stackup? Read on to find out.


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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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