Measurements of transient response on lossy microstrips with small dimensions

Measurements were made of the behavior of transient pulses on terminated microstrips with small dimensions (2.5 mu m thick and 10-40 mu m wide). The dependence of transient behavior on the width, length, and dielectric thickness of microstrips is reported, providing a guide for choosing design parameters of lossy microstrips. The experimental results indicate that these small microstrips can be used for high-speed digital signal transmission, with a rise time at least as short as 40 ps, provided that the line resistance is taken into account and that proper termination is used. Pulse attenuations are found to be consistent with purely resistive losses when the skin effect is included; no significant losses can be attributed to the polyimide dielectric. The reflection from the interface between the lossless and lossy lines is experimentally shown to be small for well-matched cases, but to be appreciable for poorly matched cases. The standard transmission theory for lossy lines under the conditions of these experiments is used successfully to describe the experimental results.<
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