A 300-GHz SPST Switch With a New Coupled-Line Topology in 65-nm CMOS Technology

A single-pole single-throw (SPST) switch operating around 300 GHz has been developed in this letter based on a 65-nm CMOS technology. The SPST switch adopts a novel coupled-line topology, in which MOSFETs are employed as a variable impedance component at the through-and coupled-ports to achieve a large isolation. Over the measured frequency band of 220-320 GHz, a minimum insertion loss of 3.9 dB (at 303 GHz) and a maximum isolation of 66 dB (at 250 GHz) were obtained. This achieved peak isolation is the largest value obtained so far beyond 100 GHz with a CMOS switch. An isolation larger than 39 dB was maintained for the entire frequency band measured. The measured return loss showed a maximum value of 29 dB at 312 GHz.