275 GHz Quadrature Receivers for THz-Band 6G Indoor Network in 130-nm SiGe Technology

We report two 275-GHz quadrature receivers (Rx’s) with mixer-first and LNA-first architectures in a 130-nm SiGe BiCMOS process. Both quadrature Rx’s contain I and Q mixers implemented with a modified Gilbert-cell mixer with swapped RF and local oscillation (LO) ports to downconvert the RF signal at 260–290 GHz to the I and Q intermediate frequency (IF) bands at 0.1–30GHz. For a cost-effective solution, a compact 260GHz quadrature LO chain is integrated with a compact frequency tripler with an E-band driving amplifier (DA), a 260-GHz DA, and a differential hybrid coupler to generate the quadrature LO signals for I and Q mixers. Comprised of a push-push doubler cascaded with a single-balanced mixer, the frequency tripler was employed to isolate the LO harmonic leakages from the IF band. A wideband IF amplifier was used for an aimed conversion gain higher than 20 dB in each channel. In the measurement, the implemented mixer-first and LNA-first Rx’s achieved a minimum single-sideband (SSB) noise figure (NF) of 22.3 and 21 dB, a peak gain of 21.4 and 27.5 dB with an IF bandwidth of 30 GHz. The amplitude and phase imbalances between the I and Q channels of the mixer-first Rx were measured around 1 dB and 4°. The fabricated mixer-firs and LNA-first chips occupy a whole area of 1.418 and 2.030 mm2, and consume a DC power of 434 and 490 mW, respectively.