This work presents a chessboard focal plane array (FPA) camera with state-of-the-art thermal and spatial resolution in the 200 600 GHz frequency range. The FPA is implemented in a 130-nm SiGe BiCMOS technology, where each antenna element is loaded with a direct detector based on heterojunction bipolar transistors (HBTs). The antenna and detector architecture, including the vias and biasing network, were optimized to achieve a noise-equivalent power (NEP) suitable for passive THz imaging. Overall, the estimated loss of the FPA is better than 4 dB between 350 and 600 GHz, of which 1.5 dB is due to ohmic losses in the FPA, 1 dB to mutual coupling between detectors, and 0.7 dB to the impedance mismatch between the detector and antenna. A prototype of 24 pixels was manufactured and mounted on the base of a silicon hyperhemispherical lens with an anti-reflection coating. Excellent spatial resolution is achieved through a tight element spacing in the fabricated FPA, which is only half the wavelength in silicon at 350 GHz and therefore consistent with the state-of-the-art. Its responsivity, noise, and radiation patterns were characterized using a quasi-optical measurement setup. The measured radiation patterns are within 1 dB of simulations, demonstrating that the integrated THz camera achieves excellent spatial resolution. Between 330 GHz and 500 GHz, the NEP was measured to be on the order of 10 pW/vHz. When considering the entire operational band, this NEP results in a noise-equivalent temperature difference (NETD) of the camera is 1.6 K for an integration time of 1 s per pixel, which is comparable to the state-of-the-art. While THz detectors with state-of-the-art sensitivity are limited to single-pixel designs, the presented work combines a multi-pixel implementation with competitive sensitivity.

This work presents a modified Marchand balun for sub-terahertz frequencies. By introducing an asymmetric ground shield in the coupler sections, low imbalance is achieved at the differential port. The proposed design is well-suited for on-wafer testing of differential power amplifiers and antennas. A prototype fabricated in a 90-nm SiGe-BiCMOS process is characterized in the 200–325 GHz range, showing good agreement with simulations. The measured amplitude and phase imbalances at 270 GHz are 0.1 dB and 2.5°, remaining lower than ±1 dB and 3.5° in the 240–290 GHz frequency range. The measured insertion loss is below 2.5 dB, while the simulated return loss in the single-ended port is better than 10 dB in the 220–340 GHz range.

This work details the design and characterization of a wideband on-chip dual-polarized double-slot antenna for sub-THz frequencies, integrated in SiGe-BiCMOS technology. The proposed design features two perpendicularly arranged double-slots that provide dual-linear polarization and efficient illumination of dielectric lenses through the silicon substrate. To decrease the level of cross-polarization, a number of parasitic slots are added. Two feeding architectures have been studied, leading to two different prototypes. The first is designed in a 130 nm SiGe-BiCMOS process and is tailored for integration with single-ended circuit topologies. It achieves a maximum antenna efficiency of 63% in its operational bandwidth of 170-250 GHz, with a cross-polarized component lower than −22 dB up to 240 GHz. The second prototype is designed in a 90 nm process and is suited for differential circuits. A 55% fractional bandwidth is achieved around the central frequency of 287.5 GHz, with a maximum antenna efficiency of 56% and a cross-polarized component lower than −19.5 dB. The port isolation is better than −37 dB up to 300 GHz. Both prototypes are characterized in the 200-325 GHz frequency range, with very good agreement between the measurements and simulations.

Dielectric spectroscopy is a label-free, non-contact, real-time, multi-layer sensing technology, and has been used for identification and quantification of many biological materials. A combination of such sensing features is in demand for monitoring of organ-on-chip systems; however available sensing technologies have yet to address this need. In this work, we explore the possibility of leveraging the inherent features of dielectric spectroscopy for the application in organ-on-chip systems, by investigating three key technological developments using open-ended coaxial probes. Firstly, biocompatible non-contact sensing capabilities are proved by showing similar sensing performance of Parylene C-coated probes and uncoated probes. Secondly, a setup and methodology are developed for highly accurate and non-destructive height positioning of the probe to allow for precise extraction of intermediate sample layers. Finally, non-contact multi-layer sensing performance of the presented technology is successfully demonstrated by means of a biological phantom in a three-layered system. With further integration, dielectric spectroscopy can potentially become a cornerstone sensing technique for organ-on-chip by enabling real-time non-contact tracking of various tissue contents and properties.

This contribution presents a silicon-integrated focal plane array (FPA) THz camera that achieves passive-level sensitivity and a densely sampled field-of-view. The FPA chip is designed in a 130nm SiGe BiCMOS technology from IHP and consists of a previously presented chessboard array topology with integrated direct detectors. The detectors are realized using a differential pair of heterojunction bipolar transistors in a common-base configuration biased in deep saturation. A silicon, hyper-hemispherical lens is mounted on the chip as a primary focusing element. The maximum responsivity of the camera is simulated to be 680 V/W at 350GHz, and above half this value between 260GHz and 600GHz. Simulations show that the minimum NEP is on the order of 2pW/√HZ, yielding an NETD of 1K for a 150ms integration time. For characterization and future imaging demonstrations, the camera is mounted in a quasi-optical setup, which refocuses the beams from the silicon lens onto an imaging plane. Measurements performed in this setup demonstrate that the camera achieves a responsivity on the order of 550/W, while also realizing a dense focal plane sampling.

This contribution presents the assessment of RDL technology at sub-terahertz frequencies based on polybenzoxazole (PBO) polymers. A stack of two PBO layers of 10μm thickness with 3 metallization of 5μm copper is being under development. Vias as small as 10μm and a separation of 60μm are being explored. To assess the materials and capabilities of this technology, GCPW, stripline transmission line structures are being assessed, expecting losses in the order of 1.3dB/mm and 2.1dB/mm respectively. Moreover, two resonators have been designed to enhance the accuracy of the characterization.

In this work, we present a numerical testbench, realized in a circuit simulation environment, enabling a priori uncertainty evaluation of dielectric spectroscopy in the application field of organs-on-chip. This testbench evaluates the impact of noise, ambient temperature variation and impurity of liquid standards on the uncertainty of dielectric spectroscopy measurements. Moreover, the proposed approach allows to account for the impact on measurement sensitivity of system parameters such as probe dimensions and probe coatings. The estimated uncertainty contributions for the considered effects are compared and benchmarked experimentally. Finally, the testbench is employed to project the dielectric spectroscopy accuracy on a relevant biological application, namely monitoring the growth of a 7 μm-thick kidney cell monolayer.

To perform the polarimetric calibration of the Antenna Dome – a fixed multi-node over-the-air measurement setup for antenna pattern characterization – a fast simulation model is developed. The model enables characterization and compensation of angle-dependent polarimetric distortions in the transmitted field of an antenna under test (AUT). An open ended waveguide and a horn antenna at 26.5 GHz are used for referencing and validation, respectively. The total power simulated at broadside with the proposed model showed an average power difference of 0.5 dB compared with the measurement results for the reference antenna. The proposed calibration method reduces the power deviation between the full-wave simulation model and the practical Dome measurement system of about 67% in the antenna used for validation. The calibration procedure compensating for systematic power imbalances across the sensing nodes and correcting angle-dependent polarization basis distortions.

This work presents a structured, CAD-assisted design flow to realize broadband on-wafer calibration structures, validated in the prefabrication phase, and extract the intrinsic device response up to (sub)mm-waves. The strict requirements imposed by the design rule checks (DRCs) of 22 nm CMOS technology are incorporated during the design phase of the fixture by using a scripted connectable tile elements approach. The minimum dimension of a critical feature of the fixture is then identified using a newly defined metric based on the correspondence between the EM field distribution in the fixture versus a non-perturbed case of the same standard (STD) artifact. A simulation test bench environment, augmented with experimental data, is then used to add the uncertainties arising from three main error contributors: vector network analyzer (VNA) receiver noise, probe placement error, and calibration residual errors. Including these errors allows for the generation of pre-silicon numerical uncertainty bounds, which are benchmarked with experimental data using calibration quality metrics and device-level parameters. Measurement results ranging from 1 to 325 GHz are presented to demonstrate the validity of the proposed approach to establish the quality of on-wafer calibration approaches integrated in the back-end of line of Si-based technologies and to validate the compact model of CMOS devices up to (sub)mm-waves.

The thermal energy radiated by silicon wafers with different conductivities is characterized experimentally in the mm and sub-mm wave ranges. These samples are heated up, and the energy that they radiate thermally is captured by different horn antennas covering the frequency band between 75 and 500 GHz. The energy radiated (in the order of pW) and collected by the horn antennas is subsequently detected by zero bias Schottky diodes. The measured thermal radiated power agrees with the prediction from Planck's law for the highly doped wafers, corresponding to high conductivities. However, for low conductivities, the measurements show a descending pattern as a function of the frequency, which is not in line with expectations from Planck's law. Parallelly, we have developed a theoretical model providing a classical explanation of these results [1].

A novel over-the-air (OTA) measurement setup for simultaneous and near-real-time characterization and mapping of the phased array radiation patterns to the error-vector-magnitude (EVM) is introduced. A cost-effective software-defined radio (SDR) system, including a Pluto SDR for both transmission and reception, is employed. For setup demonstration, the performance of a 4 × 4 active phased array antenna (APAA) is studied at 26.5 GHz. Calibration of the transmitter results in an EVM of 0.5%, proving the accuracy of the measurement system. The over-the-air measured EVM of the APAA is 1.2%. The proposed setup and approach provide deep insights into how array radiation characteristics affect signal quality, advancing the evaluation and development of APAAs for next-generation wireless communication systems.

Increasing demand for cryogenic electronics aimed at quantum sensors and computing technologies asks for accurate and quantifiable calibration methods and techniques. In this work, we present a structured approach to generate the nominal RF responses of standard artifacts, enabling wideband vector network analyzer (VNA) calibration algorithms, i.e., short, open, load, and reciprocal (SOLR), at cryogenic temperatures. Moreover, we present an EM simulation strategy to generate the perturbations in the artifacts’ responses based on mechanical fabrication tolerances and calculate an equivalent RF response uncertainty. Both the nominal and perturbed standard responses are computed at (user defined) cryogenic temperatures, by combining thermo-mechanical responses with the electromagnetic solver. A circuit simulator-based measurement model (MM) is used to compute the uncertainties of the cryogenic setups used in this work. Error contributions arising from the propagation of VNA noise, switch nonidealities, calibration artifacts uncertainties, temperature fluctuations, and temperature gradient over the interconnects are included in the MM. For validation, measured results of a coaxial air transmission line at 77 K and 4.2 K are presented and compared with 3-D EM simulation predictions. Finally, the measurement uncertainties are detailed in a budget analysis describing the individual contributions.