A D-Band SiGe TDD Front-End Featuring a Compact Asymmetric T/R Switch Enabled by Dual-Mode Reconfigurable Coupled-Lines

This paper presents a compact D-band time-division-duplex (TDD) front-end in 130-nm SiGe BiCMOS. The design features a novel, ultra-compact asymmetric T/R switch based on a reconfigurable tri-conductor coupled line, which supports differential high-power transmission and single-ended low-noise reception by toggling its coupling mode. Co-designed with the power amplifier (PA) and low-noise amplifier (LNA) matching networks, the switch directly provides the PA’s power matching and the LNA’s noise and input matching, eliminating redundant impedance transformations and minimizing insertion loss. Measurement results show that the transmitter achieves a gain of 18 dB and a maximum saturated output power of 13.7 dBm from 120 to 150 GHz, while the receiver achieves a gain of 18 dB and a minimum noise figure (NF) of 6.2 dB across 120–140 GHz. Occupying a compact 0.76 × 0.45 mm² area, this highly integrated design is well suited for large-scale D-band integrated sensing and communication (ISAC) arrays.