In this work, a design of an analog I/Q crosstalk compensation circuit in 130 nm SiGe BiCMOS is proposed. The circuit consists of four baseband variable gain amplifiers based on Gilbert cells. As a proof of concept, a 20 Gbps QPSK input signal with high bidirectional crosstalk (20% and 30 %), equal to an error vector magnitude (EVM) of 25.1 % and signal-to-noise ratio (SNR) of 12.0 dB, was improved to EVM=16.1 % and SNR= 15.9 dB at the output. Unidirectional cross-talk up to 50%, was investigated, and at 50 % the EVM improved from 25.9 % to 18.6 %, and the SNR from 11.7 to 14.6 dB.

A D-band transmitter and receiver are packaged from bare die MMICs that were designed and fabricated in a 130 nm SiGe BiCMOS technology. The packaged modules are interfaced to a WR-6.5 waveguide at the RF and coaxial connectors at the LO and IF ports. Both transmitter and receiver cover an RF frequency range of around 120-150 GHz while the required LO frequency is 1/4 of the RF frequency. A D-band communication link built with the packaged transmitter and receiver demonstrated up to 48 Gbps 16-QAM over 1-meter polymer microwave fiber (PMF), 40 Gbps 16-QAM over 2 meters PMF, and 16 Gbps QPSK over 4 meters PMF.

A D-band (110-170 GHz) ultra high data rate link is presented and characterized. The circuits are realized in a commercial 130 nm silicon germanium (SiGe) BiCMOS process. The 3-dB bandwidth for both transmitter (Tx) and receiver (Rx) is between 125 - 165 GHz, resulting in a 40 GHz bandwidth. The communication link has demonstrated transmissions up to 102 Gbps using 8-phase shift keying (PSK) modulation over a one meter long foam-cladded polymer microwave fiber (PMF) with a bit error rate (BER) of$2.1\times 10^{-3}$. Using direct quadrature phase shift keying (QPSK), 56 Gbps was reached with a BER$< 10^{-12}$. Total chip area for Tx and Rx combined, including pads, is 4.2 mm2.

A chipset for high datarate polymer microwave fiber (PMF) communication is described. It consist of a PAM-4 RF-DAC and power detector (PD) and is fabricated using a commercial 130 nm SiGe BiCMOS process. A link measurement is performed over a one meter long PMF verifying that the link can support data rates up to 20 Gbps using PAM-4, with a bit error rate (BER) of <10−12. The RF-DAC covers frequencies between 120–160 GHz, with a peak output power of 4 dBm. It has a stacked transistor pair as core and includes a frequency doubler at the LO input and a three stage amplifier at the output. The PD includes an amplifier and an active balun to suppress the fundamental frequency. Both circuits occupy only 1.54 mm2 combined, including pads. The high data-rate, energy efficiency, low cost and robustness of the link makes is suitable for short range (< 10 meters) device-to-device communication.

Three-dimensional-printing technologies have been receiving great attention for a wide variety of applications in recent years for cost effectiveness, eco-friendliness, and process simplicity in complicated structures. This paper describes the challenges and solutions of applying 3-D-printing technologies in fabricating passive millimeter-wave (mmWave) and terahertz (THz) devices. First, we review the state-of-the-art dielectric 3-D-printed passive mmWave and THz devices. Then, we focus on our novel 3-D-printed metallic passive mmWave and THz devices such as horn antennas and waveguides. Next, we analyze the dimensional tolerance and surface roughness of various 3-D-printing technologies in order to provide a guide for choosing an appropriate technology for specific applications. Finally, we summarize the current work and identify the future studies in material powder refinement, surface treatment, optimization of the print process, development of hybrid dielectric and metallic 3-D-printing technology for realizing not only simple mmWave and THz devices but also sophisticated mmWave and THz systems.

A novel FPGA-based Differential QPSK modem (modulator and demodulator) is presented for data rates up to 2.5Gbps, in which no DAC or ADC is used. The targeted application is E-Band microwave Point-to-Point radio links in mobile backhaul for LTE and beyond.