On-Chip 3-D Model for Millimeter-Wave T-Lines with Gap Discontinuity in BiCMOS Technology

Although the discontinuity structures in the microstrip transmission lines such as a gap have been largely studied, the three-dimensional edge effects, skin effects and metal losses have hardly been analyzed in the model. In this paper, an accurate model which enable high predictability for electrical behavior of on-chip 3-D transmission line with gap discontinuity is developed from equations generated with conformal mapping techniques. The model has also been used to develope gap as a library device with schematic symbol, layout parameterized cell (PCell). T-line with gap has been implemented with back end of line (BEOL) in 0.13 mum SiGe BiCMOS technology. Good correlations have been achieved up to 120 GHz among EM simulation, measurement and model, less than 2.3deg phase difference and less than 1.59 dB coupling magnitude have been achieved for all the cases. The model is scalable and can be used for the design of mm-wave passive components as well as the guideline for high density interconnects layout.