Ullrich Pfeiffer

• University of Wuppertal

This letter presents a 206.5–220.5-GHz fundamental differential Colpitts oscillator in a cascode topology implemented in a 130-nm SiGe HBT technology with f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> t </sub>/ f max of 350/450 GHz. Base inductors at the common-base (CB) stages are used to provide...

Hyperspectral imaging is a robust technique combining imaging and spectroscopy with the purpose of identifying objects’ physical nature as well as their material components under illumination simultaneously. It requires broad spectral mapping for the same spatial area. In the terahertz (THz) frequency range, many materials exhibit a distinctive tra...

This work focuses on a systematic analysis of the potential as well as the limitations of modern SiGe HBT devices for broadband passive room-temperature detection in the lower THz range. Multiple necessary conditions need to be fulfilled to facilitate broadband passive imaging with a sufficiently low in-band NEP, which refer to various technology-d...

Terahertz (THz) light-field imaging offers a solution for material identification and imaging of opaque objects. This paper explores THz techniques, including coherence-based approaches and light-field methods, showcasing experimental setups and results.

This paper presents a multi-finger doubler based on amorphous-indium gallium zinc oxide (a-IGZO) thin film transistors (TFT) operating at GHz frequency. The doubler and the TFTs have been fabricated in-house with chromium (Cr) gate electrodes. We have used the Rensselaer Polytechnic Institute amorphous silicon (RPI-a) TFT DC model and a Null-Bias m...

The terahertz (THz) frequency range is widely considered as the most challenging and under-developed frequency range due to the lack of technologies to effectively bridge the transition region between microwaves (below 100 GHz) and optics (above 10,000 GHz). Although THz radiation would be perfect for material identification and as a safe alternati...

A broadband three-stage pseudo-differential SiGe-interconnection bipolar transistor (HBT) power amplifier (PA) for high-speed communication at around 300 GHz is presented. The amplifier is fabricated in an experimental 130-nm SiGe BiCMOS technology with an $f_{t}/f_{\max }$ of 470/650 GHz. The use of asymmetric coupled line transformers is propos...

Radiation monitoring using ionisation chambers spans a wide spectrum of radiation fields from environmental monitors to ambient dose monitors near particle accelerators. Hence the output generated by these sensors can vary from few femtoamperes to microamperes. They require specific front-end electronics that can accurately measure the generated cu...

Terahertz (THz) systems open up the possibility of new applications of electromagnetic waves. Enormous bandwidths up to several terahertz enable the development of powerful spectroscopy systems that can provide insights into the structure and material of objects with micrometer resolution. New high power and compact THz time-domain spectroscopy (TD...

This article presents a comprehensive analysis of the terahertz (THz) rectification process with modern high-speed silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) devices to enable low-power and close-to-optimum detector sensitivity in a near-THz fractional bandwidth. The influence of all major device internal parasitics on the det...

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 lo...

Due to the wide practical use and its availability worldwide, wireless communication has been one of the main applications driving the development of microelectronic technology. This drive will persist in the future, where wireless networks with data rates of 100 Gb/s are already envisioned by the new IEEE 802.15.3d-2017 standard. Currently, the ma...

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- $\mu \text{m}$ SiGe HBT technology and combined with wire-bonded chip-on-board (COB) packaging for high-speed baseband...

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 extend...

Flexible energy harvesting devices fabricated in scalable thin-film processes are crucial for wearable electronics and the Internet of Things. We present a flexible rectenna based on a one-dimensional junction metal–insulator–graphene diode, offering low-noise power detection at terahertz (THz) frequencies. The rectennas are fabricated on a flexibl...

Flexible energy harvesting devices fabricated in scalable thin-film processes are important components in the field of wearable electronics and the Internet of Things. We present a flexible rectenna based on a one-dimensional junction metal-insulator-graphene diode, which offers low-noise power detection at terahertz (THz) frequencies. The rectenna...

This article 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 beam-width (HPBW), and radiation power. For concept validation, the frequency-dependent far-field radiatio...

The performance of terahertz (THz) dispersive spectroscopes is limited in spectral resolution and frequency accuracy due to a finite pixel count. This letter demonstrates that increasing the synthetic effective pixel count by exploiting super-resolution (SR) imaging results in improved performance. To this end, we investigated the performance of a...

Radiation detectors need front-end electronics capable of measuring currents over a large dynamic range with femtoampere sensitivity. The goal of this work is to find an alternative to the legacy systems implemented using discrete components or technology nodes of 350 nm or higher. The 130 nm technology is evaluated on its leakage current performan...

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...

In this article, we present a comprehensive study to understand the image formation and associated resolution limitations of hyper-hemispherical high-resistivity floating-zone silicon (HRFZ-Si) lens-integrated terahertz (THz) cameras, and we extend this understanding into THz super-resolution imaging applications. Along these lines, design tradeoff...

For mobile THz applications, integrated beam steer- ing THz transmitters are essential. Beam steering approaches using leaky-wave antennas (LWAs) are attractive in that regard since they do not require complex feeding control circuits and beam steering is simply accomplished by sweeping the operating frequency. To date, only a few THz LWAs have bee...

In this letter, we demonstrate amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) with a maximum transit frequency ( ${f}_{T}$ ) of 1.1 GHz and maximum oscillation frequency ( ${f}_{max}$ ) of 3.1 GHz, which set a new record for metal-oxide TFTs based on scalable and cost-effective process techniques. A key for the outstandin...

This article presents a terahertz (THz) source system-on-a-chip (SoC) specifically designed for computational imaging with a single-pixel camera (SPC). The SoC consists of an $8\times 8$ array of independent, frequency-unlocked THz sources that together radiate maximum 10.3-dBm power at 0.42 THz. Each source pixel is composed of a fundamental Col...

A novel 3-D multilayer packaging technology for integrating an array of indium phosphide (InP)-based terahertz photodiodes (THz-PDs) with a rectangular waveguide power combiner (WR-PC) is proposed. The packaging concept is based on a vertical integration of an InP THz-PDs array with a multilayered WR-PC made of metallized glass-reinforced epoxy FR4...

In the above article [1] , errors occurred in [15] and the biographies of Ullrich Pfeiffer and Janusz Grzyb. The correction information is provided as follows.

There is a need to reduce the cost and size of functional terahertz devices, in order to expedite this notoriously under-utilized frequency band toward practical applications. Electronic integrated circuits (ICs) are extremely useful to this end, as they provide a means to achieve miniaturization and mass-production, leveraging the foundries and te...

This paper discusses advances related to the integration of future mobile electronic THz systems. Without claiming to provide a comprehensive review of this surg- ing research area, the authors gathered research on selected topics that are expected to be of relevance for the future exploration of components for practical mobile THz imaging and sens...

In this article, a polarization-diversity technique multiple-input multiple-output (MIMO) is demonstrated to double the spectral efficiency of a line-of-sight quadrature phase-shift keying (QPSK) wireless link at 220-255 GHz with a pair of highly integrated single-chip transmitter (TX) and receiver (RX) front-end modules in 0.13-μm SiGe HBT technol...

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 swit...

As fifth generation (5G) research is maturing towards a global standard, the research community has started to focus on the development of beyond-5G solutions and the 2030 era, i.e. 6G. In the future, our society will be increasingly digitised, hyper-connected and globally data driven. Many widely anticipated future services will be critically depe...

In this work, a silicon lens-coupled dual-polarization on-chip ring antenna for THz direct detection in 0.13-μm SiGe HBT technology is presented. In particular, various circuit-antenna co-design aspects are addressed, including the detector frequency-dependent driving impedance and responsivity, and the necessity of accommodating multiple DC signal...

This letter presents a 1-m wireless link established with a set of fundamentally operated Tx/Rx direct-conversion in-phase and quadrature (IQ) radio frequency (RF) front-end modules in a 0.13-μm SiGe HBT technology featuring full chip-on-board packaging. Using a 16-quadrature amplitude modulation, data rates from 20 to 100 Gb/s with an error vector...

The objective of this letter is to show the potential of amorphous indium gallium zinc oxide (IGZO) thin-film transistors (TFT) for designing radio frequency (RF) communication systems operating in the gigahertz regime. For that purpose, the self-mixing operation of in-house fabricated IGZO-TFTs beyond their transit frequency (f <sub xmlns:xlink="h...

Traditional 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 tec...

This paper presents a fully integrated system-on-a-chip for real-time terahertz super-resolution near-field imaging. The chip consists of 128 sensing pixels with individual cross-bridged double 3-D split-ring resonators arranged in a 3.2 mm long $2\times 64$ 1-D array. It is implemented in 0.13- $\mu \text{m}$ SiGe bipolar complementary metal–oxi...

The failure to accurately define tumor margins during breast conserving surgery (BCS) results in a 20% re-excision rate. The present paper reports the investigation to evaluate the potential of terahertz imaging for breast tissue recognition within the under-explored 300 – 600 GHz range. Such a frequency window matches new BiCMOS technology capabil...

This paper presents a fully-integrated direct-conversion fundamentally-operated mixer-first quadrature receiver module with a tunable LO in the 219–266 GHz band. It has been implemented in a 0.13-μm SiGe heterojunction bipolar transistor technology. It includes an on-chip LO path driven externally from the printed circuit board (PCB) connector leve...

Breast Cancer is one of the most frequently diagnosed cancer diseases worldwide, and the most common invasive tumour for women. As with all cancers, early detection plays a major role in reducing the mortality and morbidity rate. Currently, most breast cancers are detected due to clinical symptoms, or by screening mammography. The limitations of th...

This paper presents a fully-integrated direct-conversion quadrature transmitter and receiver implemented in a SiGe HBT technology with fT/fmax=350/550 GHz working at a carrier frequency of 240 GHz. The transmitter has a 3-dB RF/LO bandwidth of 35 GHz with a peak output power of 8.5 dBm, while the receiver presents 22 GHz of RF/LO 3-dB bandwidth wit...

Terahertz (THz) imaging and tomography are modern imaging techniques allowing 2D and 3D inspection of objects over a broadband frequency range. However, the transfer of this technique to medical applications is limited to surface or subsurface inspection due to the large concentration of water molecules which are an intrinsic characteristic of biol...