Vias between routing layers induce interconnection discontinuities. Signal reflection on the trace is enhanced because of these discontinuities. Via would be a noise source as the signal frequency increases. The reflection fraction changes with the via geometry properties, especially via height. This paper focuses on the influence of via height on signal reflection. Vias height from 250 μm to 1500μm are studied under high frequency by simulation. The reflection loss caused by via increases with via height nonlinearly. Considering the reflection, an optimization criterion for via design is provided.
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