Radio Frequency Switch Research Articles

Investigation and Research of High-Performance RF MEMS Switches for Use in the 5G RF Front-End Modules

In this article, based on the developed methodology, the stages of designing two designs of high-performance radio-frequency single-pole single-throw microelectromechanical switches are investigated. These radio-frequency microelectromechanical switches are designed to operate at a central resonant frequency of 3.6 GHz and 3.4 GHz, respectively, as well as to work both in mobile communication devices and in the design of the architecture of 5G mobile networks, in particular in arrays of integrated antennas and radio-frequency interface modules. The manufacture and study of two designed structures are researched. For the first manufactured experimental sample in the open state the insertion loss is no more than -0.69 dB and the reflection loss is -28.35 dB, and in the closed state the isolation value is at least -54.77 dB at a central resonant frequency of 3.6 GHz. For the second in the open state the value of the insertion loss is no more than -0.67 dB and the reflection loss is -20.7 dB, and in the closed state the isolation value is not less than -52.13 dB at the central resonant frequency of 3.4 GHz. Both manufactured experimental samples are characterized by high linearity, as well as a small value of contact resistance in the closed state.

Highly Scalable, Flexible, and Frequency Reconfigurable Millimeter‐Wave Absorber by Screen Printing VO2 Switch Array onto Large Area Metasurfaces

AbstractFlexible and reconfigurable (FAR) electronics are in high demand for emerging applications, including wearable, bioelectronics, and internet of things. Highly scalable antenna arrays or periodic surfaces are required for high directivity or electromagnetic wave path control, particularly for 5G millimeter‐wave (mm‐wave) due to high path losses. Conventional lumped tuning components have limitations related to scalable FAR electronics and hence highly scalable and flexible vanadium dioxides (VO2) switch array is proposed for mm‐wave applications. A frequency reconfigurable mm‐wave absorber is designed by screen printing the VO2 switch array to demonstrate the proposed approach feasibility for large scale electronics, achieving high scalability, tunability, and flexibility because the 40 µm thick VO2 switch array satisfies radio frequency switch requirement. Flexibility and repeatability are tested up to 2000 bending cycles with 25 mm bending radius, and tunability and scalability are demonstrated with 300 ON/OFF ratio, and 98% product yield for 400 switches printed on 144 × 144 mm2 polyethylene terephthalate substrates. Absorption frequency is switchable from 14 to 28 GHz at 150 mm bend radius while retaining better than 90% absorptivity as a frequency reconfigurable mm‐wave absorber. Therefore, the proposed VO2 switch array would be suitable for scalable 5G and 6G FAR electronics.

High Al-content AlGaN channel high electron mobility transistors on silicon substrate

The rapidly increasing power demand, downsizing of power electronics and material specific limitation of silicon has led to development of AlGaN/GaN heterostructures. Commercial GaN power devices are best available for radio frequency (RF) and high voltage switching applications. Emerging AlxGa1-xN channel based heterostructures are promising to enhance the limits of next generation high voltage GaN power switching devices. In this work, we report on the study of electrical performance of AlGaN channel HEMTs-on-Silicon using various Al content. The fabricated devices exhibited outstanding buffer breakdown electric field above 2.5 MV/cm considering the submicron thin heterostructures grown on silicon substrate. Furthermore, we also experimentally demonstrate high temperature operation of fabricated AlGaN channel HEMTs.

Beamwidth-Reconfigurable Circularly Polarized Slot Antenna Based on Half-Mode Substrate-Integrated Waveguide

Beamwidth-reconfigurable antennas are useful for the intersatellite link of low earth orbit formation flying and constellation, as they prevent unauthorized satellites from eavesdropping. In this article, a circularly polarized slot array antenna based on a half-mode substrate-integrated waveguide (HMSIW) for the K-band beamwidth reconfiguration is proposed using a new radio frequency (RF) switch structure and a pair of modified −45° and +45° linearly polarized HMSIW slot arrays for the dual operation of a single-pole double-throw (SPDT)/a power divider (PD) and easy integration with other components, respectively. The RF switch structure consists of a T-junction PD, λ/4 lines, and beam lead PIN diodes with current control resistors and without a DC block circuit for low DC power consumption and size reduction. The −45°/+45° linearly polarized HMSIW slot arrays providing linear and circular polarizations (LP and CP, respectively) are operated for CP. The use of a short-circuited termination instead of dissipative termination results in easier integration with other components because the 16 radiating slots consume most of the input power. The dimension of the beamwidth-reconfigurable antenna including the bottom metal layer is 157.2 × 23.3 × 0.254 mm3 (12.5λ0 × 1.86λ0 × 0.0202λ0). The RF switch for the SPDT shows the insertion losses of 1.8–2.3 and 16.7–24.2 dB and an isolation of 20.9–33.4 dB for both outputs within the 10-dB bandwidth. The RF switch for the PD has an insertion loss of 3.9–4.8 dB. The one- and two-antenna operation modes of the CP antenna provide the gains of 9.44 and 6.99 dBic, the axial ratios of 2.24 and 3.47 dB, and the horizontal beamwidths of 35.8° and 78.2°, respectively.

Multi-Person Breathing Detection With Switching Antenna Array Based on WiFi Signal

WiFi sensing, an emerging sensing technology, has been widely used in vital sign monitoring. However, most respiration monitoring studies have focused on single-person tasks. In this paper, we propose a multi-person breathing sensing system based on WiFi signals. Specifically, we use radio frequency (RF) switch to extend the antennas to form switching antenna array. A reference channel is introduced in the receiver, which is connected to the transmitter by cable and attenuator. The phase offset introduced by asynchronous transceiver devices can be eliminated by using the ratio of the channel frequency response (CFR) between the antenna array and the reference channel. In order to realize multi-person breathing perception, we use beamforming technology to conduct two-dimensional scanning of the whole scene. After eliminating static clutter, we combine frequency domain and angle of arrival (AOA) domain analysis to construct the AOA and frequency (AOA-FREQ) spectrogram. Finally, the respiratory frequency and position of each target are obtained by clustering. Experimental results show that the proposed system can not only estimate the direction and respiration rate of multi-person, but also monitor abnormal respiration in multi-person scenarios. The proposed low-cost, non-contact, rapid multi-person respiratory detection technology can meet the requirements of long-term home health monitoring.

Array Element Selection Strategies for Interference Suppression in Reconfigurable Tripole Antenna Array Systems

Compared with the scalar array, the polarization-sensitive array (PSA) possesses a more powerful anti-jamming ability in adaptive array processing. However, each antenna of the traditional PSA requires two or more radiofrequency (RF) front-ends, which results in proliferation in computational complexity and even configuration redundancy that has little impact on performance. Besides, the RF front-end is much more expensive than the antenna, making the cost extremely high when considering a large PSA. Therefore, it is essential to search for a PSA reconfiguration approach that utilizes fewer RF front-ends and can generate excellent interference rejection performance. In this work, we devise a new PSA reconfiguration strategy, termed dipole selection, to employ fewer dipoles and RF front-ends to acquire a high signal to interference plus noise ratio (SINR). And the strategy is implemented by controlling the RF switch between the RF front-end and the dipole. The polarization-spatial correlation coefficient (PSCC), characterizing the difference between desired signal and interference in the polarization-spatial domain, is proposed to analyze the effect of PSA reconfiguration on anti-interference performance. Subsequently, the problem of dipole selection is addressed with two proposed methods, named Quadratic-Over-Linear Fraction (QOLF) and Correlation Measurement Elimination (CME), respectively. Numerical and experimental simulation results demonstrate the correctness and effectiveness of the proposed strategy and approaches.

A low insertion loss RF switch using a 130 nm SOI process

To realize a better radio frequency (RF) communication system, the RF switch, as an important module, is used to cooperate with other devices to form an RF front end for optimizing communication performances. This paper designs a single-pole multi-throw (SPMT) RF switch, which exhibits a low insertion loss of 0.57 dB at 1.9 GHz under the voltage of 2.2 to 4.7 V. The RF switch is fabricated using a 130 nm silicon-on-insulator (SOI) complementary metal-oxide-semiconductor (CMOS) process. It can be used in multi-frequency and multi-mode applications such as 4G/5G. The proposed RF switch has competitive performance and can be combined with other modules to achieve better wireless communication and promote the development of ultra-wideband and multi-mode wireless communication systems.

Empirical laser measured with optical coherent quadrate amplitude modulation receiver for upgrading fiber optic systems

Abstract The work clarified the empirical laser measured with optical coherent quadrate amplitude modulation receiver for upgrading fiber optic systems. Peak signal amplitude and output power spectrum are measured after light receivers under the control of extinction modulator ratio, radio frequency switching voltage and switching bias voltage. The better the fiber optic system performance can be achieved with the higher values of extinction ratio, both switching radio frequency and bias voltages based LiNb modulators.

Full-band Monte Carlo simulation of two-dimensional electron gas in (AlxGa1−x)2O3/Ga2O3 heterostructures

β -Gallium oxide (Ga2O3) is an extensively investigated ultrawide-bandgap semiconductor for potential applications in power electronics and radio frequency switching. The room temperature bulk electron mobility (∼200cm2V−1s−1) is comparatively low and is limited by the 30 phonon modes originating from its 10-atom primitive cell. The theoretically calculated saturation velocity in bulk is 1–2×107cms−1 (comparable to GaN) and is limited by the low field mobility. This work explores the high field electron transport (and hence the velocity saturation) in the 2DEG based on the first principles calculated parameters. A self-consistent calculation on a given heterostructure design gives the confined eigenfunctions and eigenenergies. The intrasubband and the intersubband scattering rates are calculated based on the Fermi’s golden rule considering longitudinal optical (LO) phonon–plasmon screening. The high field characteristics are extracted from the full-band Monte Carlo simulation of heterostructures at 300 K. The overall system is divided into a 2D and a 3D region mimicking the electrons in the 2DEG and the bulk, respectively. The electron transport is treated through an integrated Monte Carlo program which outputs the steady state zone population, transient dynamics, and the velocity–field curves for a few heterostructure designs. The critical field for saturation does not change significantly from bulk values, however, an improved peak velocity is calculated at a higher 2DEG density. The velocity at low 2DEG densities is impacted by the antiscreening of LO phonons which plays an important role in shaping the zone population. A comparison with the experimental measurements is also carried out and possible origins of the discrepancies with experiments is discussed.

Reconfigurable adaptive polarisation‐sensitive array optimisation for multiple interferences elimination in satellite communication

Polarisation-sensitive array (PSA) has earned extensive attention in satellite communication owing to excellent anti-interference performance. Nevertheless, the configuration of traditional PSA where each polarised antenna requires multiple radio frequency (RF) front-ends makes it much more costly in terms of hardware and software for system design. In this paper, resorting to RF switches, a novel reconfigurable PSA optimisation technique is developed that utilises fewer RF front-ends, which can considerably decrease computational expenditure and achieve high anti-jamming performance. An RF switch switching (RFSS) scheme is devised to guide the implementation of PSA reconfiguration. To accurately demonstrate the effect of the array configuration on interference rejection performance, the polarisation-spatial subspace correlation coefficient (PSC) is presented. Then the relationship between the optimal signal to interference plus noise ratio (SINR) and the PSC based on adaptive processing is formulated. Aiming to acquire the optimal reconstructed PSA outputting the maximum SINR, the mathematical model of the PSA reconfiguration problem is established. Subsequently, two optimisation methods are provided to address the problem efficiently, thereby gaining the optimal configuration of the reconstructed PSA and implementing the reconfiguration by RF switches. Numerical and experimental simulations verify the correctness and reliability of the developed scheme and approaches.

Tunable and reconfigurable bandstop filters enabled by optically controlled switching elements

The authors report a novel approach for designing tunable and reconfigurable bandstop filters by employing bias-free optically-controlled photoconductive radio frequency (RF) switching elements. To verify the effectiveness of the approach, a bandstop filter with two stopbands centred at 4.05 and 4.75 GHz was designed using a split-ring-coupled microstrip transmission line on RO3010 substrates. To enable reconfigurability, a micromachined Si chip with a thickness of ∼73 μm was embedded in the gap of each resonator. The tuning and reconfiguring of the filter are accomplished by selectively illuminating the Si chips using fibre-coupled laser diodes with a wavelength of 808 nm. By turning on and off each laser diode, the filter stop bands can be dynamically reconfigured. In addition, the suppression of each stop band can be continuously and independently tuned by changing the light intensity from 0 to 20 W/cm2. With geometric scaling, this approach is promising for realizing a novel class of compact and high-performance tunable and/or reconfigurable circuits from the microwave to mmW-THz region.

Flexible radio-frequency micro electro-mechanical switch towards the applications of satellite communications

This paper presents a flexible radio-frequency microelectromechanical system (RF MEMS) switch integrated on cyclo-olefin polymer (COP) substrate using a modified surface MEMS processing technology, which could be used in the 17–19 GHz frequency band of satellite communication. Through systematic simulation analysis, it is found that flexible RF MEMS switch can achieve certain bending radius by miniaturizing the electronic dimension, without degrading the RF performance. It is demonstrated that the RF characteristics of flexible RF MEMS switch with special anchor structural design, fabricated by modified surface MEMS processing, are not sensitive to bending deformation under the curvature of 0 mm−1, 0.05 mm−1, 0.10 mm−1. Furthermore, the range of bending curvature which will affect the RF characteristics is given through systematic simulation. The flexible RF MEMS switch with high process compatibility and stable RF performance is believed to be promising candidates for future microwave communications and other consumer electronics.

A Neuro-Space Mapping Method for Harmonic Interference Prediction of SOIFET Radio Frequency Switches

With the rapid development of wireless communication, the requirements of high-integration and low-cost radio frequency (RF) front-end modules in mobile phones result in more usage of silicon-on-insulator field effect transistors (SOIFETs) for the manufacturing of RF switches. However, the nonlinear behavior of SOIFET switches in <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> -state always produces unwanted harmonics distortion interference when they are excited by a large signal. In this article, we simplify the well-known physics-based surface potential model to an interelectrode nonlinear capacitance (INC) model since it adequately describes the harmonic effects produced by the transistor. The INC model, referred to as the coarse model, cannot match the behavior of the real switch, since many parameters of the switch cannot be accurately determined. This article proposes a novel dynamic neuro-space mapping network model, referred to as the fine model, to optimize the INC model. The proposed model takes advantage of the high accuracy of the fine model and the fast speed of the coarse model. Ultimately, the proposed method can accurately predict the harmonics interference for SOIFET switches in the complex RF front-end environment and provides an intuitive guideline under the design stage to prevent EMI problems.

Substrate-Induced Dissipative and Non-Linear Effects in RF Switches: Probing Ultimate Performance Based on Laser-Machined Membrane Suspension

With the evolution of radio frequency (RF)/microwave technology, there is a demand for circuits that are able to meet highly challenging RF front end specifications. Silicon-on-insulator (SOI) technology is one of the leading platforms for upcoming wireless generation. The degradation of performance due to substrate coupling is a key problem to address for telecommunication circuits, especially for the high throw count switches in RF front ends. In this context, a fast, flexible and local laser ablation technique of the silicon handler allows for the membrane suspension of large millimeter-scale circuits. This approach enables the evaluation of the ultimate performance in the absence of the substrate, i.e., without dissipative losses and substrate-induced non-linear effects, on capacitive comb coupling structures and RF switches. Compared to high-resistivity SOI substrates, the high frequency characterization of RF membrane switches reveals a superior linearity performance with a reduction in second and third harmonics by 17.7 dB and 7.8 dB, respectively. S-parameter analysis also reveals that membrane suspension entails insertion losses that are improved by 0.38 dB and signal reflection lowered by 4 dB due to a reduced off-state capacitance. With reference to a trap-rich substrate, the membrane suspension also achieves an additional 7.8 dB reduction in the second harmonic, indicating that there is still scope for improvement in this figure of merit. The obtained results demonstrate a new way to evaluate optimized circuit performance using post-fabrication substrate engineering.

Memristive technologies for data storage, computation, encryption, and radio-frequency communication

Memristive devices, which combine a resistor with memory functions such that voltage pulses can change their resistance (and hence their memory state) in a nonvolatile manner, are beginning to be implemented in integrated circuits for memory applications. However, memristive devices could have applications in many other technologies, such as non–von Neumann in-memory computing in crossbar arrays, random number generation for data security, and radio-frequency switches for mobile communications. Progress toward the integration of memristive devices in commercial solid-state electronic circuits and other potential applications will depend on performance and reliability challenges that still need to be addressed, as described here.

Nanowatt Integrated Circuits and Systems [Guest Editorial

Power consumption has become a critical concern in the design of integrated circuits (ICs) and systems, such as broadband circuits, single-chip radio-frequency (RF)/millimeter-wave (mm-wave) transceivers, phase shifters, multiplexers, RF switches, frequency dividers, equalizers, tunable filters, switched attenuators, and tunable delay lines. Long neglected, the topic of low-power digital design has vaulted to the forefront in recent years, due to a wide range of new applications, from 5G/6G communications, mobile computing, artificial intelligence, and the Internet of Things (IoT) to big data, the cloud, and edge computing.

Chalcogenide Phase-Change Material Germanium Telluride for Radio-Frequency Applications: An overview

Chalcogenide phase-change materials (PCMs) have been widely used in optical storage media and nonvolatile memory devices applications. Over the past several years, there has been interest in exploiting PCM technology, especially germanium telluride (GeTe) and its alloys, for radio-frequency (RF) applications. The principle of operation of PCM-based RF devices is based on the ability of the material to transform from a high-resistivity (amorphous phase) to low-resistivity state (crystalline phase) and vice versa, with the application of a short, thermal pulse. Actuation pulses are applied to microheaters embedded with the PCM junction to switch between the two states. The PCM switch can exhibit more than five orders of resistance change between the two states. PCM-based RF switches are expected to bridge the gap between semiconductor switches and microelectromechanical systems (MEMS) switches as they combine the low insertion loss performance of MEMS technology and the small size and reliability performance of semiconductor technology. In addition to miniaturization, GeTe-based switches offer unique latching functionality and ease of monolithic integration with other RF circuits. This article presents an overview of PCM technology and its applications to RF circuits. A brief history of the technology is presented first, followed by a discussion of the basic characteristics of PCMs. The steps of a fabrication process of PCM RF devices are illustrated. A description of RF-PCM switch is presented in detail along with a comparison between RF performance of PCM switches and other existing commercial switches. As examples of application of the PCM technology to other RF circuits, the article concludes by presenting a crossbar switch matrix, phase shifter, and variable attenuator, realized using the PCM technology.

Electrically Induced Liquid Metal Droplet Bouncing.

Liquid metals, including eutectic gallium–indium (EGaIn), have been explored for various planar droplet operations, including droplet splitting and merging, promoting their use in emerging areas such as flexible electronics and soft robotics. However, three-dimensional (3D) droplet operations, including droplet bouncing, have mostly been limited to nonmetallic liquids or aqueous solutions. This is the first study of liquid metal droplet bouncing using continuous AC electrowetting through an analytical model, computational fluid dynamics simulation, and empirical validation to the best of our knowledge. We achieved liquid metal droplet bouncing with a height greater than 5 mm with an actuation voltage of less than 10 V and a frequency of less than 5 Hz. We compared the bouncing trajectories of the liquid metal droplet for different actuation parameters. We found that the jumping height of the droplet increases as the frequency of the applied AC voltage decreases and its amplitude increases until the onset of instability. Furthermore, we model the attenuation dynamics of consecutive bouncing cycles of the underdamped droplet bouncing system. This study embarks on controlling liquid metal droplet bouncing electrically, thereby opening a plethora of new opportunities utilizing 3D liquid metal droplet operations for numerous applications such as energy harvesting, heat transfer, and radio frequency (RF) switching.

Electron irradiation-induced defects for reliability improvement in monolayer MoS2-based conductive-point memory devices

Monolayer molybdenum disulfide has been previously discovered to exhibit non-volatile resistive switching behavior in a vertical metal-insulator-metal structure, featuring ultra-thin sub-nanometer active layer thickness. However, the reliability of these nascent 2D-based memory devices was not previously investigated for practical applications. Here, we employ an electron irradiation treatment on monolayer MoS2 film to modify the defect properties. Raman, photoluminescence, and X-ray photoelectron spectroscopy measurements have been performed to confirm the increasing amount of sulfur vacancies introduced by the e-beam irradiation process. The statistical electrical studies reveal the reliability can be improved by up to 1.5× for yield and 11× for average DC cycling endurance in the devices with a moderate radiation dose compared to unirradiated devices. Based on our previously proposed virtual conductive-point model with the metal ion substitution into sulfur vacancy, Monte Carlo simulations have been performed to illustrate the irradiation effect on device reliability, elucidating a clustering failure mechanism. This work provides an approach by electron irradiation to enhance the reliability of 2D memory devices and inspires further research in defect engineering to precisely control the switching properties for a wide range of applications from memory computing to radio-frequency switches.

A Fractal-Based Time-Modulated Multiband Linear Array for Interband Communication

A novel method of utilizing the repetitive self-similar propertyof the cantor set fractal (CSF) pattern in synthesizing a time-modulated linear array (TMLA) with multiband characteristics, applicable for interband communication, is proposed. The fractal pattern of different growth stages is used to constitute subarrays (SAs) and each group of the subarrayed elements is periodically modulated via a single radio frequency (RF) switch. A closed-form array factor (AF) expression of the proposed CSF&#x2013;TMLA is derived, and through representative results, it is shown that a <i>P</i>th stage CSF-TMLA is eligible to be functional at &#x201C;<i>P</i>&#x201D; intercommunication bands with power patterns of the same sidelobe level. It is further investigated that the number of RF switches and, hence, the unknown optimization variables essentially entailed to synthesize the array are drastically reduced.