Parametric Analysis and Design Guidelines for mm-Wave Transmission Lines in nm CMOS

This paper focuses on nm CMOS transmission line design as distributed passive elements and their application in mm-wave integrated circuits. A variety of transmission lines such as coplanar waveguides (CPWs), shielded coplanar waveguides (SCPWs), and CPW with ground are analyzed in terms of their geometry and electrical properties. The parametric analysis of the various line types is based on a combination of experimental and simulated data. The slow wave effect of the SCPW is proved to result in better performance, size reduction, and reduced costs compared to the regular CPW. From parametric analysis, a simple set of tests is derived that can easily indicate the capabilities of a certain process design kit in terms of a transmission line design. Finally, in an effort to further reduce silicon area and respective cost, a design technique is proposed with a semilumped CPW transmission line using metal-oxide-metal capacitors as loading elements. This semilumped CPW design achieves nearly double-phase constant per length over the regular CPW and is highly attractive for mm-wave CMOS design.