An Analysis and Characterization of Filter-Shapes for Distributed Power Architectures.

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High-Speed data networking designs require very high quality power to minimize power supply jitter, thus optimizing product performance. Filter-shapes, printed circuit board shapes underneath dc/dc converter modules for power filtering, are simple in concept yet difficult to model electrically. This paper introduces the concept of filter-shapes, their potential gains, hidden costs and associated risks. The primary objectives of this paper were to assess the value of modeling filter-shapes and to characterize their actual effectiveness. To achieve this, direct measurements were performed on a typical telecom design test case, and filter-shape impedance was modeled for the test case using three different methods: the self-inductance, the effective inductance, and the 3D EM field solver approach. Our findings indicate that filter-shapes do enhance power supply filtering, and modeling can be performed with reasonable accuracy.