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A highly integrated fundamentally operated direct-conversion quadrature (IQ) TX/RX chipset with a tunable carrier of 215-240 GHz for high-speed wireless communication is presented. The TX/RX front-ends are fabricated in the 0.13-μm SiGe HBT technology and combined with wire-bonded chip-on-board (COB) packaging for high-speed baseband (BB) signaling. For test purposes, the chipset features a dedicated dual-polarization architecture with a suitable on-chip antenna to allow controlled variation in I-to-Q channel leakage resulting from frequency-dependent upper sideband (USB)/lower sideband (LSB) asymmetry in the RF path of the jointly operated TX and RX and the corresponding analysis of its impact on system error vector magnitude (EVM) of the complete link. The analysis is aided by system-level BB-referred problem formulation with similarity to the classical IQ error in the local oscillator (LO) and BB paths. While operated in a loop-back configuration, the front-ends support the LO-dependent BB-referred channel bandwidth (BW) of 16-20 GHz at the board level with the typical free-space-related double sideband (DSB) Psat/OP1 of 7/3.5 dBm and single sideband (SSB) conversion gain (CG)/noise figure (NF) of 7.5/17.5 dB for the TX and RX, respectively. Under regular working conditions, data rates above 80 Gb/s are demonstrated for 16-quadrature amplitude modulation (QAM) modulation in a 0.6-m line-of-sight wireless characterization setup, with the maximum of 100 Gb/s at 225 GHz. The achievable speeds are limited by frequency-dependent USB/LSB asymmetry in the RF path resulting in systematic error vector floor independently of the underlying SNR and IQ error. With elimination of the asymmetry-incurred I-to-Q leakage from the RF path, the potential of increasing the data rates to at least 120-140 Gb/s is shown, indicating the severeness of this RF impairment for wide modulation bandwidth.

Arrays of terahertz (THz) sources provide a pathway to overcoming the radiation power limitations of single sources. Several independent sources of THz radiation may be implemented in a single integrated circuit, thereby realizing a monolithic THz source array of high output power. Integrated THz sources must generally be backside-coupled to extended hemispherical dielectric lenses in order to suppress substrate modes and extract THz power. However, this lens also increases antenna gain and thereby produces several non-overlapping beams. This is because individual source pixels are relatively large. Hence, their spatial separation on-chip translates to angular separation in the far-field. In other words, there are gaps in their field of view into which very little THz power is projected. Therefore, they cannot homogeneously illuminate an imaging target. This article presents a simple, practical, and scalable method to convert arrays of incoherent THz sources into a diffuse, uniform illumination source without the need for reducing pixel size. Briefly, individual beam divergence is optimized by tailoring the dimensions of the extended hemispherical dielectric lens such that the far-field beams of adjacent source pixels overlap and combine to form a uniform far-field beam. We applied this method to an incoherent 8 × 8-pixel THz source array radiating 10.3 dBm at 0.42 THz as a proof of concept and thereby realized a 10.3-dBm 0.42-THz diffuse, uniform illumination source that was then deployed in a demonstration of THz active imaging.

This paper presents the concept of a lens-integrated CMOS camera-type terahertz (THz) compact antenna test range (CATR) to determine the far-field characteristics of transmitters (TX), including the radiation pattern, directivity, half-power beamwidth (HPBW), and radiation power. For concept validation, the frequency-dependent far-field radiation pattern of a 0.6–1.1 THz TX equipped with a 23.7–28.2 dBi standard gain horn antenna was measured using THz CATR. Directivity, HPBW, and radiation power have been extracted from THz CATR measurements. The first two parameters are compared to values obtained from calculations, full-wave simulations, and reference measurements performed at a conventional far-field range. In contrast, the third parameter is compared to a reference measurement performed with an absolute power meter. The following performance was achieved employing super-resolution imaging. Frequency-dependent directivity and HPBW were determined within a root mean square (RMS) accuracy of 0.85 dB and 1.16°, respectively, related to reference measurements performed at the conventional far-field range. The frequency-dependent radiation power was determined within an RMS accuracy of 0.7 µW related to reference measurements with the absolute power meter. Camera-related limitations concerning the THz CATR application are discussed in detail, such as field-of-view limitations, angular resolution limits, scan loss, pixel-to-pixel variation, signal-to-noise ratio limitations, and the interaction between TX and camera lens., This document is the accepted manuscript version that has been published in final form in IEEE Transactions on Terahertz Science and Technology at https://doi.org/10.1109/TTHZ.2021.3088286. © 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

For mobile THz applications, integrated beam steering THz transmitters are essential. Beam steering approaches using leaky-wave antennas (LWAs) are quite attractive in that regard since they do not require complex feeding control circuits because beam steering is simply accomplished by sweeping the operating frequency. To date, only a few THz LWAs have been reported. These LWAs are based on polymer or graphene substrates and thus it is quite impossible to monolithically integrate these antennas with state-of-the-art indium phosphide (InP) based photonic or electronic THz sources and receivers. Therefore, in this paper, we report on an InP-based THz LWA for the first time. The developed and fabricated THz LWA consists of a periodic leaking microstrip line integrated with a grounded coplanar waveguide to microstrip line (GCPW-MSL) transition for future integration with InP-based photodiodes. For fabrication, a substrate-transfer process using silicon as carrier substrate for a 50 m thin InP THz antenna chip has been established. By changing the operating frequency from 230 GHz to 330 GHz, the fabricated antenna allows to sweep the beam direction quasi-linearly from -46 to 42, i.e. the total scanning angle is 88. The measured average realized gain and 3 dB beam width of a 1.5 mm wide InP LWA are ~11 dBi and 10. The paper furthermore discusses the use of the fabricated LWA for THz interconnects.

This paper reports investigations led on the combination of the refractive index and morphological dilation to enhance performances towards breast tumour margin delineation during conserving surgeries. The refractive index map of invasive ductal and lobular carcinomas were constructed from an inverse electromagnetic problem. Morphological dilation combined with refractive index thresholding was conducted to classify the tissue regions as malignant or benign. A histology routine was conducted to evaluate the performances of various dilation geometries associated with different thresholds. It was found that the combination of a wide structuring element and high refractive index was improving the correctness of tissue classification in comparison to other configurations or without dilation. The method reports a sensitivity of around 80% and a specificity of 82% for the best case. These results indicate that combining the fundamental optical properties of tissues denoted by their refractive index with morphological dilation may open routes to define supporting procedures during breast-conserving surgeries.

This letter presents a 210–291-GHz $8\times $ multiplier chain in the 0.13- $\mu \text{m}$ SiGe Bipolar CMOS (BiCMOS) technology for the broadband generation of carrier signals, imaging, and spectroscopy. It consists of three cascaded Gilbert-cell doublers with compact input matching networks to generate quadrature collector currents in the switching quad for broadband flat conversion gain. The multiplier chain generates a saturated output power of −7.7 dBm at 244.5 GHz with a 3-dB bandwidth of 81 GHz. It consumes 0.24 W of dc power and occupies 0.86 mm 2 of chip area.

Measurement of total ionizing dose in a radiation field is efficiently carried out by ionisation chambers. The paper details the design of a mixed-signal ASIC for the front-end electronics of ionisation chambers. A single chip solution for ultra-low current measurement is designed by combining the current processing analog section realized using low leakage thick gate transistors and the data handling digital section implemented using fast thin gate transistors. The design succeeds in limiting the cross coupling between the two circuit domains using deep n-wells and guard rings. The ASIC fabricated in 130 nm technology attains a wide dynamic range of −7 fA to −20μA with maximum error in measurement less than ±4 %. The ASIC occupies an area of 3.52 mm 2 and has a total power consumption of 17.4 mW. The femtoampere range input leakage current of the ASIC contributed primarily by the ESD diodes was found to be varying exponentially with temperature. Dose rate measurements from 5 μ Sv/h to 7.4 Sv/h is demonstrated by interfacing the ASIC to an ionisation chamber.