A high quality vertical transition between GCPW and SMCPW lines in multilayer technology

A high quality vertical transition from DC up to 20 GHz between GCPW and SMCPW lines is presented. In order to design this transition a circuit model has been developed. This model is directly extracted from the geometry of the transition using closed expressions and gives unprecedented insight into the sensitivity of the design to its different constitutive elements. Thus, it provides an easy way to find suitable initial dimensions for the transition in a circuit simulator, thereby greatly reducing the effort spent in subsequent electromagnetic simulations. A comparison between circuit and electromagnetic simulations shows very good agreement in the analyzed situation. Careful measurements were taken on a fabricated transition with a back- to-back configuration showing a return loss greater than 20 dB for all ranges considered.