A 285–310 GHz CMOS Switch Using Inductive Matching and Floating-Body Techniques for Metasurfaces: Design and Equivalent Circuit Model

This paper presents a compact-size switch operating in the frequency range of 285 to 310 GHz, employing the standard 65-nm CMOS process. The terahertz performance of the switch is enhanced through a custom-designed inductive loop that resonates with the parasitic capacitance of the switch. Additionally, the floating-body technique is employed to mitigate leakage. The probe tests and the Thru-Reflect-Line (TRL) calibration tests are conducted to extract the equivalent impedance of the switch within the operating frequency range. Comparative experiments are conducted to evaluate the impact of using the two techniques on the switch's performance. Furthermore, a comparison between simulation and measurement results of the proposed switch is performed. Equivalent circuit models are introduced based on the physical structure of proposed switch, and the fitted parameters are presented. The fabricated switch, with a compact footprint of merely 30 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μm</i> × 40 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μm</i>, achieves a measured insertion loss of 1.5 dB in the ON state and more than 6.0 dB of isolation in the OFF state within the operating frequency range and can be effectively employed as a tunable component in metasurface applications.