International Journal of Microwave and Wireless Technologies cambridge.org/mrf Research Paper Cite this article: Carpenter S, He ZS, Zirath H (2018). Multi-functional D-band I/Q modulator/ demodulator MMICs in SiGe BiCMOS technology. International Journal of Microwave and Wireless Technologies 10, 596–604. https:// doi.org/10.1017/S1759078718000338 Received: 1 September 2017 Revised: 6 February 2018 Accepted: 8 February 2018 First published online: 3 April 2018 Key words: Frequency mixers; RF front-ends; I/Q modulator/demodulator Author for correspondence: Sona Carpenter, E-mail: sona@chalmers.se © Cambridge University Press and the European Microwave Association 2018 Multi-functional D-band I/Q modulator/demodulator MMICs in SiGe BiCMOS technology Sona Carpenter, Zhongxia Simon He and Herbert Zirath Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Göteborg, Sweden Abstract This paper presents the design and characterization of a D-band (110–170 GHz) monolithic microwave integrated direct carrier quadrature modulator and demodulator circuits with on- chip quadrature local oscillator (LO) phase shifter and radio frequency (RF) balun fabricated in a 130 nm SiGe BiCMOS process with f t /f max of 250 GHz/400 GHz. These circuits are suitable for low-power ultra-high-speed wireless communication and can be used in both homodyne and heterodyne architectures. In single-sideband operation, the modulator demonstrates a maximum conversion gain of 9.8 dB with 3-dB RF bandwidth of 33 GHz (from 119 GHz to 152 GHz). The measured image rejection ratio (IRR) and LO suppression are 19 dB and 31 dB, respectively. The output P 1dB is -4 dBm at 140 GHz RF and 1 GHz intermediate frequency (IF) and the chip con- sumes 53 mW dc power. The demodulator, characterized as an image reject mixer, exhibits 10 dB conversion gain with 23-dB IRR. The measured 3-dB RF bandwidth is 36 GHz and the IF bandwidth is 18 GHz. The active area of both the chips is 620 μm × 480 μm including the RF and LO baluns. A 12-Gbit/s QPSK data transmission using 131-GHz carrier signal is demonstrated on modulator with measured modulator-to-receiver error vector magnitude of 21%. Introduction After the 60 GHz ISM-band and the E-band (71–76 and 81–86 GHz), the next frequency band in point-to-point links is the D-band (110–170 GHz). This frequency band is attractive for compact and lightweight point-to-point applications such as backhaul links for 5 G mobile networks, inter-satellite communication, low-latency wireless high-definition television (HDTV) transmission, and high-resolution imaging systems [1–3]. The D-band has a rela- tively low atmospheric attenuation (1 dB/km) between two high attenuation points at 118 GHz (resonance of O 2 molecule) and at 183 GHz (resonance of H 2 O molecule) which can be used for multiple gigabit communication with 1 km hop length [4–6]. The 141– 148.5 GHz frequency band is allocated by the Federal Communication Commission (FCC) for fixed and mobile communication [7]. This 7.5 GHz available bandwidth combined with high spectral efficiency modulation is capable of an ultra-high capacity backhaul links compar- able with E-band link distance. This ISM bandwidth of 1 GHz about 122.5 GHz will be mainly used for industrial, medical, and security sensors in Europe and the USA [8]. Quadrature modulation and demodulation can be performed directly at the carrier fre- quency to reduce the complexity of the transmitter and receiver systems. Quadrature mixers are therefore preferred blocks in future millimeter wave (mmWave) systems. For increased capacity and spectrum efficiency, the front-end circuits, therefore, need to be able to support complex modulations. However, beyond 100 GHz, the designs challenges are the increased parasitic effect, device model inaccuracy, and limited transistor performance. A 25 Gbit/s data rate over a distance of 10 m with on–off keying (OOK) modulation was demonstrated at 220 GHz in [9]. A binary phase shift keying (BPSK) 40 Gbit/s over a wave- guide at 240 GHz was exhibited in [10]. Nippon Telegraph and Telephone Corporation (NTT) has demonstrated a hop length of 5.8 km at a bit rate of 10 Gbit/s using OOK [11] and 20 Gbit/s using quadrature phase shift keying (QPSK) [12] in a laboratory environment at 120 GHz. An amplitude shift keying, OOK, or BPSK are simple and reliable modulation schemes but have low spectrum efficiency (<1 bit/s/Hz). The spectral efficiency can be increased by using more complicated modulation techniques, such as multilevel phase shift keying (PSK) or multilevel quadrature amplitude modulation (QAM). We have previously demonstrated a 48 Gbit/s data transmission on integrated frontend at 144 GHz using QPSK modulation over a 1.8 m distance in [13] and also using higher order QAM modulation scheme. https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1759078718000338 Downloaded from https://www.cambridge.org/core. 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