Improving Insertion Loss and Isolation in Germanium Telluride‐Based Radiofrequency Switch Using Coplanar Waveguide Layout Optimisation

Radiofrequency (RF) switches are essential building blocks of reconfigurable RF front‐ends in cellular, radar and satellite communication systems. Growing demand for high‐performance modules has strained conventional technologies, as mainstream platforms such as RFSOI CMOS exhibit parasitic limitations in the millimetre wave (mmWave) regime, restricting them to narrowband, low‐throw implementations and often requiring active circuitry that increases power consumption and linearity degradation. Phase‐change materials (PCMs) offer an alternative due to large resistivity contrast, intrinsic non‐volatility and energy‐efficient switching. Germanium telluride (GeTe)‐based RF switches, in particular, show low insertion loss and high isolation with stable behaviour up to the onset of mmWave band. Building on these advantages, this work aims to extend operational efficiency further into the mmWave range without inducing the typical isolation‐insertion loss trade‐off. Full‐wave electromagnetic simulations of a four‐terminal GeTe SPST switch are performed, incorporating a substrate‐embedded microheater, variable barrier layer thickness and preservation of coplanar waveguide (CPW) geometry. Comparative analysis of interrupted versus continuous CPW ground planes reveals that continuous grounding enhances E and H‐field confinement, yielding a 9.43 dB isolation improvement and a 1.2 dB insertion loss reduction at 60 GHz. The optimised design attains <0.4 dB insertion loss and >36 dB isolation across DC‐60 GHz.