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This contribution presents an electronic travel aid for blind and visually-impaired people based on a millimeter wave radar and a traditional white-cane. It not only represents an advanced system able to warn the user of potential obstacles, but also discerns between human and nonhuman targets. Since real scenarios would likely have moving targets, a new range alignment technique has been proposed with the aim of detecting the tiny chest displacement due to the physiological activity as the key sign of the human presence. The proposed system is able to properly recognize humans in complex environments with multiple moving targets, thus providing to the user a complete set of information, namely presence, position and nature of the available targets. The operating principle and the effectiveness of the system are shown both by simulated case studies and by employing a 122 GHz radar board for carrying out suitable measurements.

In this article, a new sensing approach for the automatic detection and ranging of human targets in cluttered environments is detailed. The person detection does not require to preliminarily define a target threshold, thus minimizing the likelihood of false alarm events. Moreover, the proposed approach allows to resolve the artifacts due to the presence of multiple objects within the same radiation beam without increasing the system complexity and cost. A powerful graphical representation, denominated range-breathing graph, is exploited for quickly making the reader aware of the exact human location, employing the breathing rate as the key element for discerning between humans and non-human targets. The method is analytically described while exhaustive simulations are carried out for confirming the reliability and suitability of the method with regard to the state of art. The effectiveness of the range-breathing separation approach is demonstrated by using two different radar boards operating at the frequencies of 24 GHz and 122 GHz. The obtained results show the general validity of this approach for identifying humans in complex cluttered scenarios

In this article, a novel tunerless technique aimed at extracting the noise parameters of on-wafer transistors is experimentally validated. In detail, the effectiveness of the method has been confirmed by employing two different setups in two remotely located laboratories. The obtained noise parameters exhibit the level of accuracy typical of the standard source tuner-based Lane technique, without the well-known limitations due to the microwave tuner. The theoretical bases of the technique have been straightforwardly illustrated, and an extensive measurement campaign has been carried out on GaAs pHEMTs to confirm the suitability of the proposed approach. Furthermore, the technique can be applied to determine the contribution of additional thermal noise sources. The developed technique might represent the core of an automatic noise parameters’ extraction test bench.

Long-term sedentary behavior severely increases the risk of developing diseases and syndromes. Cardiovascular and skeletal muscle issues, higher blood pressure and cholesterol levels are among this long list of consequences. Although a great effort was devoted to fight sedentary behaviors by means of public health strategies and the employment of wearable devices, an effective and flexible technology enabling reliable worker monitoring still does not exist. This contribution is aimed to provide an advanced solution based on microwave radars for monitoring the sitting time and recognizing a worker's proper physical activities. The adoption of the radar technology is required to provide the unobtrusive wellness sensing while enabling advanced activity and vital signs monitoring. The proposed radar sensor is able to monitor the worker's breathing activity during his worktime and track his position by preserving the individual privacy in a safe and cost-effective way. Moreover, by exploiting the human micro-Doppler signature, it recognizes different activities such as standing up, sitting down and physical exercise. The basic principles of the radar sensing and processing in health care are illustrated whereas the detection of different activities is experimentally demonstrated, highlighting the potential and the advanced features of the proposed solution.

In this paper, a millimeter-wave radar operating at the frequency of 120 GHz is employed as an aid for people with neurodegenerative disorders. In detail, an interferometric approach is exploited for detecting the movement of the head and the eyes blinking. As a matter of fact, these actions are among the very few ways to enable the communication of a person with the surrounding environment in case of heavy neurodegenerative disorder. The theoretical principles and the relevant aspects of the proposed solution are shown by simulating the entire scenario, whereas the effectiveness of the system is experimentally demonstrated.

This article presents a novel technique to remove the radar self-motion effects (RSMs) for an accurate detection of human vital signs. As opposed to the commonly used techniques, the proposed approach does not require any additional sensor, and instead, it extracts the RSM from the signals reflected by stationary clutters. Since the proposed technique requires to accurately identify the clutter range, two procedures for its automatic identification are proposed, aimed to detect both small and large radar motions. Besides allowing precise and reliable vital sign detection, it provides a compact, lightweight, comfortable, and cost-effective solution since potentially intrusive additional sensors are not required. Simulations have been carried out for validating the proposed approach, with an insight on the influence of different clutter radar cross sections on the sensitivity. Moreover, the effectiveness of the RSM cancellation has been experimentally demonstrated, showing its suitability for different applications, e.g., radar on moving platforms, vibrating tools, handheld devices, unmanned aerial vehicles, and cars.

Special Issue:Devices and Circuits for Millimeter Wave and THz Applications ispartof: International Journal Of Numerical Modelling-Electronic Networks Devices And Fields vol:33 issue:3 status: published

This paper deals with an accurate experimental investigation of the optical sensing behavior of a microwave low-noise amplifier (LNA). The tested amplifier, employing a commercial InGaAs pHEMT has been analyzed in terms of the scattering parameters and the noise figure. The analysis has been carried out by observing how the device behavior is influenced by a continuous wave laser illumination for different optical wavelengths, power levels, and bias conditions. It has been assessed that the LNA performance is significantly influenced by the light exposure with optical effects more pronounced at higher wavelengths for a fixed incident power. Upon applying the recommended bias conditions of the sensing amplifier, the main changes consist of a degradation of the noise figure and gain. As opposite to this, an overall performance enhancement is clearly recognizable with the amplifier biased at the transistor pinch-off. The results obtained in the present work fully confirm a theoretical analysis previously carried out by employing different devices and LNA design.

The aim of this study is to disclose how the performance of a gallium nitride (GaN)-based X-band low-noise amplifier is modified by applying a blue-ray (404 nm) laser beam. The tested amplifier employs an aluminium gallium nitride/GaN (AlGaN/GaN) high electron mobility transistor on silicon carbide whose dc and noise behaviour have been first analysed with and without optical illumination. Mild improvement of the gain together with severe degradation of the noise figure has occurred during light exposure with the amplifier operating according to the recommended bias condition. Conversely, pronounced improvement of the performance has taken place when the amplifier has been biased close to the transistor pinch-off point. The results presented in this work follow a previous intense activity carried out on devices and amplifiers based on gallium arsenide technology.

For the first time, the experimental values of the noise parameters of a set of GaAs pHEMT obtained through the standard source tuner-based Lane technique and a new size-based, tuner-less technique, are compared. The noise parameters have been obtained independently by 2 renowned microwave laboratories after sharing the same set of devices. The laboratories are located at the University of Messina, Italy, and at the US Naval Research Laboratory in Washington, DC. This paper demonstrates 2 new accomplishments: that the noise parameters obtained through the new tuner-less technique are equivalent to the noise parameters obtained through the standard tuner-based technique; and that the new tuner-less extraction has been extended successfully up to 26 GHz. The new size-based technique supports the implementation of an automatic noise parameters extraction in a similar fashion to the automatic determination of scattering parameters.

In this paper, a millimeter-wave radar cane for enhancing the mobility of visually impaired and blind people is presented. The system exploits a compact 122 GHz radar system that can be easily integrated on the stick. The millimeter-wave radar cane is able to detect obstacles in the area scanned by the user, providing a feedback about their distance. Moreover, it is capable of discerning between human and non-human obstacles by detecting their breathing vital sign. This is not a straightforward task due to the concurrent little chest displacement to be measured and the movements of both the user and the human target. The operating principle and the feasibility of the proposed solution are shown by simulating the entire scenario, whereas the effectiveness of the system is demonstrated by employing a 122 GHz radar board.

This paper reports a thorough overview on the last developments concerning the vital sign detection and the human localization employing the multiple-input-multiple-output (MIMO) technology. The wireless motion and vital sign detection represents an outstanding research area aimed at monitoring the health conditions of human subjects and at detecting their presence in different environments with minimal concern. MIMO radars exhibit several interesting advantages over conventional single-input-single-output architectures mainly related to their angle detection capabilities and enhanced signal-to-noise ratio. This paper describes the main features and details the operating principles of MIMO technology. Thereafter, it summarizes the state-of-the-art of the available solutions with the purpose of fueling the research activities on this hot topic.

This letter is aimed at discovering and analyzing anomalous phenomena affecting millimeter-wave FETs, focusing on a GaN HEMT as a case study. For the first time, we show that the real parts of the impedance parameters can increase and then decrease with frequency, due to the resonance of the extrinsic reactive elements. This resonance may be detected as a peak in the magnitude of the short-circuit current-gain. Such a peak is found to be substantially bias and temperature insensitive and to manifest at frequencies higher than the other current-gain peak (CGP), due to the resonance between intrinsic capacitances and extrinsic inductances, giving origin to the double CGP.

This contribution deals with the microwave linear characterization and noise figure measurement of four on-wafer GaAs pseudomorphic high-electron mobility transistors having scaled gate widths. The proposed measurement campaign has been fulfilled in two different laboratories: The University of Messina, Italy and US Naval Research Laboratory, Washington, DC, USA. Two equivalent approaches have been straightforwardly employed: a standard tuner-based technique and a novel tuner-less technique. The effectiveness of the novel technique has been confirmed as carried out independently by the two laboratories, evidencing the benefits of both techniques. The proposed experimental activity highlights the applicability of the tunerless technique for the noise characterization of advanced on-wafer devices without the constraint imposed by the addition of a source tuner to the standard measurement setup.

This invited contribution is aimed at presenting a thorough knowledge, a critical understanding, and new insights into the kink effect in the output reflection coefficient (S 22 ) of field-effect transistors (FETs). To accomplish this challenging goal, we report a measurement-based investigation, using the high-electron-mobility transistor (HEMT) technology as a case study. The kink effect is investigated over a wide range of operating conditions, by changing bias point, ambient temperature, device size, and semiconductor technology. The origin of the kink phenomenon and its dependency on the operating condition are analyzed by using a lumped-element equivalent-circuit model. The achieved findings represent a powerful know-how to entitle microwave engineers to take properly the kink effect into account in fabrication, modeling, and design phases.

This paper presents the effects of optical radiation on the behavior of two scaled-gate aluminum gallium nitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs). The tested devices, having a gate width of 100 and 200 &micro, m and a gate length of 0.25 &micro, m, were exposed to a laser beam with a wavelength of 404 nm (blue-ray) in order to investigate the main optical effects on the DC characteristics. Owing to the threshold shift and the charge generation, a marked increase of the gate and drain current was noticed. The occurrence of the kink effect in the absence of light exposure was identified, and a hypothesis about its origin is provided. The obtained results agree with the analysis previously carried out on gallium arsenide (GaAs)-based devices.

This paper comprehensively reviews the state of the art of Heating, Ventilation, and Air-Conditioning (HVAC) control sensing. The topic has broad impacts on society, by affecting energy consumption, Earth's climate, and the environmental health. Great effort was taken by researchers to study and test new technologies and methodologies for improving HVAC energy efficiency, but this large amount of works is often fragmentary, and a complete and recent review paper does not yet exist. This paper aims at filling this gap by clarifying the key points of HVAC sensing, the main technologies, and their pros and cons. The advancement in this sector is fueled by the premium performance of the embedded systems exploited as sensors and their beneficial features. The state of the art of the available solutions has been summarized with the purpose of fueling and better organizing the research effort on this hot topic. Particular attention has been paid to investigate not only the performance and reliability of the current systems but also the advanced features that can be provided by the newly evolved and complex technologies, e.g., the radar technology that has been identified as the emerging one in this field.

This paper deals with a flexible CAD methodology for the design of a microwave extra wideband filter introducing a notch at a desired frequency. The structure, designed in a cost-effective planar microstrip technology to operate in the 5–20 GHz frequency band, is capable of covering up to 120% of fractional bandwidth. It shows good performance in terms of in-band and out-of-band insertion loss and group delay. Furthermore, a simple relationship between the notch frequency and a single geometrical parameter of the structure has been extracted, thus making the component highly flexible to design. The procedure steps and the relevant design results are reported, including the electromagnetic analysis of the port connectors. Finally, different samples of the filter have been realized and measured to test the procedure. The experimental results have shown a good agreement with the expected performance thus confirming the effectiveness of the proposed methodology.

The small-signal equivalent circuit modeling of microwave field-effect transistors (FETs) is an evergreen and ever flourishing research field that has to be up-to-date with technological developments. Hence, modeling techniques must be continuously adapted and extended to suit best evolving technologies. The extraction of a FET high-frequency small-signal equivalent circuit is a very active and broad research area of significant interest, owing to its use as a prerequisite for noise and large-signal modeling. The aim of this invited article is to provide in-depth knowledge, critical understanding, and new insights into how to extract a FET small-signal equivalent circuit from both theoretical and practical perspectives. To illustrate potential solutions to the key challenges faced by researchers, experimental results for different semiconductor technologies are reported and discussed. The study is focused on the hot research topic of the cold approach that has been, and still is, the most widely used technique for extracting FET small-signal models and on the active role of the transconductance for successful modeling. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2016.

The objective of this work is to study the electrical characteristics of a nanoscale SOI Tri-Gate n-channel fin field-effect transistor (FinFET) structure with 8 nm gate length using Semiconductor TCAD tools. ATLASTM tools are computer programs which allow for the creation, fabrication, and simulation of semiconductor devices in three dimensions with different models under consideration. The drain current, transconductance, threshold voltage, subthreshold slope, leakage current, drain induced barrier lowering, and IOn/IOff current ratio are analyzed in the various biasing configuration. In addition, FinFET device with a high value of gate dielectric constant exhibits much better performance compared to the Si3N4 dielectric material, which is desirable for high performance low-power/low-voltage applications. It is found that increasing the high-k value was beneficial in reducing the subthreshold slope, DIBL, and leakage current. General Terms Integrated Circuit, VLSI, FinFET Device Modeling.

This paper presents an innovative methodology for detecting the presence of a child in the car seat or on the back seat of the vehicle. The goal of this project is to avoid the incidents where children being left inside a car die of heatstroke.The core of the system is represented by a radar whose transmitted signal has been modulated by a saw-tooth waveform from the 79 to 81 GHz. The capability of the system to detect a child or an infant has been demonstrated by means of a properly tailored simulation scenario. Moreover, the transmitting/receiving antenna array has been designed in planar technology and the relevant parameters have been reported.

This study presents a systematic experimental analysis of the noise figure and the gain of an optical sensing low-noise amplifier (LNA) in the X-band region (8.5–10.5 GHz). The study has been carried out with the purpose of analysing the effects of a 635 nm optical radiation on the gain and noise figure of the LNA, by modifying the bias operating points. Upon varying the bias conditions from those suggested into the component datasheet towards the device pinch-off, the role of the light exposure changes from causing degradation of the gain and noise figure into a clear performance enhancement. In the middle, a bias condition is found where the above LNA parameters become unresponsive to light exposure. Whilst the detrimental role played by the strong gate current increase under light exposure on the noise figure degradation is already clear, the experimental results show that close to pinch-off this effect is completely overcome by the drain current and transconductance increases.

This paper analyzes the thermal dependence of high-periphery GaN-on-SiC HEMT performance. The proposed approach is based on artificial neural networks (ANNs) that are used to model the scattering parameters versus temperature and frequency under a high dissipated power condition for a GaN HEMT with a gate width of 1.5 mm. The modeling results agree very well with measurements up to 65 GHz in the whole considered temperature range going from 35°C to 200°C, confirming the high accuracy and the good generalization capability of the proposed ANN approach.

This review deals with a comprehensive description of the available electromagnetic travel aids for visually impaired and blind people. This challenging task is considered as an outstanding research area due to the rapid growth in the number of people with visual impairments. For decades, different technologies have been employed for solving the crucial challenge of improving the mobility of visually impaired people, but a suitable solution has not yet been developed. Focusing this contribution on the electromagnetic technology, the state-of-the-art of available solutions is demonstrated. Electronic travel aids based on electromagnetic technology have been identified as an emerging technology due to their high level of achievable performance in terms of accuracy, flexibility, lightness, and cost-effectiveness.

In this paper, the challenging task of the 50 Ω noise figure measurement of mismatched devices has been addressed by tailoring a microwave virtual test-bench in a computer-aided design environment. The effects of the real measurement chain on the device noise figure as well as that of the noise figure meter and noise source have been taken into account by characterizing and modeling every component. The effectiveness of the simulation has been proven by comparing the virtual test-bench noise figure with that calculated from the measured scattering and noise parameters of a 0.15 µm pHEMT in the 2–26 GHz frequency range. Hereby, all the processes involved in the 50 Ω noise figure measurements of mismatched devices have been presented by a visual and user-friendly interface. By this original approach, a fast evaluation of each component role in the measurement chain can be accomplished. A performance estimation of the system can be performed and updated in a simple way whenever a component is replaced. Finally, since every step of the procedure has been disclosed and extensively clarified, it might be used as a training tool for microwave engineers.

In this paper a small-signal and noise modeling approach is developed and applied to GaN HEMTs. The main advantage of the proposed method is its simplicity and dependency on only pinch-off S-parameter measurements. The achieved model shows good fitting with microwave experiments performed on nonlinear solid-state devices with different sizes. The model reliability is further confirmed by the observed scaling of the extracted parameters.

In this paper, a virtual test-bench for extracting the 50 Ω noise factor of mismatched devices has been tailored in a CAD environment. Every component of the measurement chain has been experimentally characterized and it has been employed as a sub-circuit. Moreover, the relevant electrical models have been extracted for taking into account the influence of each subcircuit in the chain. Evidence of the simulation effectiveness is provided by comparing the test-bench data with the noise factor calculated from measured scattering and noise parameters in the 6–18 GHz frequency range. The proposed virtual test-bench is not only a valid tool for the challenging task of accurate 50 Ω noise factor measurements of mismatched devices, but also for the sensitivity analysis of each component in the chain, thus evaluating how they affect the accuracy of the final result. Moreover, it can be used for building an automated and customizable measurement chain. Finally, it might be employed as a training tool since every step of the measurement is precisely analyzed and all the steps involved within the 50 Ω noise factor extraction are extensively clarified.