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In search of novel detectors of electromagnetic radiation at terahertz frequencies, field-effect transistors (FETs) have recently gained much attention. The current literature studies them with respect to the excitation of plasma waves in the two-dimensional channel. Circuit aspects have been taken into account only to a limited degree. In this paper, we focus on embedding silicon FETs in a proper circuitry to optimize their responsivity to terahertz radiation. This includes impedance-matched antenna coupling and amplification of the rectified signal. Special attention is given to the investigation of high-frequency short-circuiting of the gate and drain contacts by a capacitive shunt, a common approach of high-frequency electronics to induce resistive mixing in transistors. We theoretically study the effect of shunting in the framework of the Dyakonov–Shur plasma-wave theory, with the following key results. In the quasistatic limit, the capacitive shunt induces the longitudinal high-frequency field needed in the FET’s channel for resistive mixing. In the non-quasi-static case, the shunt’s role is taken over by plasma waves. Rectification can then be described as distributed self-mixing in the transistor’s channel. Based on such considerations as well as other circuit-related aspects, we arrive at a rational design for FET-based detectors of terahertz radiation, and implement the first monolithically integrated 0.65 THz focal-plane array including antennas and amplifiers on a single silicon die. The measured performance data compare well with the theoretical predictions.

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Traditional terahertz (THz) equipment faces major obstacles in providing the system cost and compactness necessary for widespread deployment of THz applications. Because of this, the field of THz integrated circuit (THz IC) design in CMOS and SiGe HBT technologies has surged in the last decade. An interplay of advances in silicon process technology, design technique, and microelectronic packaging promises to narrow the gap between the requirements and the reality of system cost and performance of THz components. Furthermore, the scalability, reconfigurability, and signal processing features of silicon technology have initiated research in complex THz ICs that expand the functionality of THz systems; this has enabled new applications, methods, and algorithms. This paper reviews the progress in THz IC research and investigates several realizations of THz imaging and sensing applications with silicon-based components regarding their motivation, system performance, and challenges. THz computed tomography, broadband multicolor imaging, high-resolution FMCW radar imaging, subwavelength resolution near-field imaging, and compressed sensing are presented.

A 0.13-m SiGe BiCMOS double-conversion superheterodyne receiver and transmitter chipset for data communications in the 60-GHz band is presented. The receiver chip includes an image-reject low-noise amplifier (LNA), RF-to-IF mixer, IF amplifier strip, quadrature IF-to-baseband mixers, phase-locked loop (PLL), and frequency tripler. It achieves a 6-dB noise figure, 30 dBm IIP3, and consumes 500 mW. The transmitter chip includes a power amplifier, image-reject driver, IF-to-RF upmixer, IF amplifier strip, quadrature baseband-to-IF mixers, PLL, and frequency tripler. It achieves output P 1dB of 10 to 12 dBm, P sat of 15 to 17 dBm, and consumes 800 mW. The chips have been packaged with planar antennas, and a wireless data link at 630 Mb/s over 10 m has been demonstrated.Index Terms-Low-noise amplifier, millimeter-wave integrated circuits, mixer, power amplifier, SiGe, superheterodyne receiver, superheterodyne transmitter, V-band, voltage-controlled oscillator (VCO), 60 GHz.