High-Q Slow-Wave Coplanar Waveguides

TL;DR

This paper investigates methods to maximize the quality factor of slow-wave coplanar waveguides, demonstrating a sevenfold increase in Q through optimized design parameters and substrate configurations in CMOS technology.

Contribution

It introduces a comprehensive optimization approach for coplanar waveguide design, including geometry and substrate stacking, to significantly enhance Q performance.

Findings

Measured Q increased over 7 times with optimized design

Achieved Q > 70 at 24 GHz in 0.18 μm CMOS

Critical design parameters include conductor widths, spacing, and substrate stacking

Abstract

A comprehensive study of methods of maximizing Q for slow-wave coplanar waveguides is described. In addition to the widths of the signal conductor and coplanar ground lines and the distance between them, the length, spacing and stacking of the metal layers of the substrate shield strips are also shown to be critical in maximizing performance. Measured results from more than 50 different devices show that a 7X increase in the quality factor (e.g., Q > 70 at 24 GHz in 0.18 {\mu}m CMOS) is achievable using the optimum topology with optimum dimensions.