Microwave Transmission Line Design Across Split Reference Planes

The design for high-speed channels within electronic packaging traditionally focuses on interconnect and packaging solutions pertaining primarily to the signal conductor portion of a transmission line. However, the overall construct and path between driver and receiver includes not only the signal, but also the image return path, requiring the Signal Integrity engineer to pay close attention to the round-trip current path. Traditionally, this means that discontinuities in the ground return path are avoided at all cost. This paper will investigate deviations from this traditional mode of operation by exploring an application requiring intentionally designed traces over ground discontinuities. Additionally, the authors explore modeled and measured results obtained from constructs posed as alternatives to discontinuous ground transmission lines.