A unified model and direct extraction methodologies of various CPWs for CMOS mm-wave applications
In this paper, a novel unified model for various CPWs, including standard coplanar waveguides (CPW), grounded CPW (GCPW), CPW with slotted shield (SCPW), and corresponding direct extraction methodologies are proposed and investigated. In the SPICE-compatible model, a new C-L-R series path in the parallel branch is introduced to describe the electromagnetic coupling for CPWs with large lower ground or shield, while other kinds of high frequency effects including substrate loss, and skin effect are considered to explain the frequency-dependent per-unit-length Lx, Cx, Rx, and Gx parameters. The direct extraction procedure are established which can ensure both accuracy and simplicity compared with other reported methods. The model is verified by IBM 90nm CMOS processes with SLOT de-embedding techniques. Excellent agreement between the model and the measured data for different CPWs is achieved up to 67GHz. The direct extraction methodologies ensure the feasibility and availability of scalable modeling of CPWs for circuit designer.