The Effects of Line Width and Slot Etching on Silicon-Based CPW at MM-Wave Frequencies

An experimental study is in progress to investigate the performance of coplanar waveguide (CPW) transmission lines which are printed on high-resistivity silicon. In one sample group a nominal characteristic impedance of 50 Ω is maintained while the ground plane spacing and ground plane width are varied. In this group conventional CPW lines are included, as well as lines in which the slots have been etched to create a triangular-shaped recess between the center conductor and ground planes. The slot-etching technique is known to be an effective method to decrease attenuation, and is demonstrated here with measurements up to 67 GHz. In another group of samples identical lines with and without etching are characterized to determine the difference in attenuation and characteristic impedance. All lines used in this work are classified as finite ground CPW (FGC), as the ground plane width is comparable to the slot and center conductor dimensions.