Reconfigurable Function Research Articles

A dual-band, beam steering and polarization reconfigurable 2-bit array antenna for satellite navigation/communication applications

A dual-band array antenna for satellite navigation/communication applications with beam steering and reconfigurable polarization functions is proposed in this paper based on four 2-bit antenna units. The 2-bit antenna unit works in the dual frequency range of 1.55–1.65 GHz (GPS L1, GLONASS L1, GSNS L1, Beidou-2 B1) and 2.0–2.2 GHz (Mobile Satellite Service, MSS, downlink), and its phase can be controlled by PIN diodes flexibly. Therefore, the proposed array antenna has dual-band and beam steering characteristics. Besides that, the polarization of the proposed array antenna can be changed by covering a metasurface and rotating it at different angles. The measured results indicate that the proposed array antenna can achieve linear polarization (LP), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). The proposed array antenna can realize LP beam steering within 45° and CP beam steering within 30° at 1.6, 2.0, and 2.2 GHz.

A sliding mode observer approach to oscillatory fault detection in commercial aircraft

The Flight Control System (FCS) is one of the most important systems in all modern aircraft. For such systems it is required to have robust Fault Detection Isolation and Reconfiguration (FDIR) functionalities with high detection performance. In this work we specifically consider the Oscillatory Failure Cases (OFC), which, if not mitigated, can cause additional structural loads for which the aircraft is not designed. A Sliding Mode Observer (SMO) based detection method is proposed for fast and consistent detection of these OFC faults. A benchmark of a generic aircraft FCS equipped with OFC simulation capabilities, as well as the presented solution for detection, have previously been presented within a competition at the 2020 IFAC World Congress.

Wideband low-scattering metasurface with an in-band reconfigurable transparent window

Active metasurfaces with dynamically reconfigurable functionalities are highly demanded in various practical applications. Here, we propose a wideband low-scattering metasurface that can realize an in-band reconfigurable transparent window by altering the operation states of the PIN diodes loaded on the structures. The metasurface is composed of a band-pass frequency selective surface (FSS) sandwiched between two polarization conversion metasurfaces (PCMs). PIN diodes are integrated into the FSS to switch the transparent window, while a checkerboard configuration is applied in PCMs for the diffusive-reflective function. A sample with 20×20 elements is designed, fabricated, and experimentally verified. Both simulated and measured results show that the in-band functions can be dynamically switched between beam-splitting scattering and high transmission by controlling the biasing states of the diodes, while low backscattering can be attained outside the passband. Furthermore, the resonant structures of FSS also play the role of feeding lines, thus significantly eliminating extra interference compared with conventional feeding networks. We envision that the proposed metasurface may provide new possibilities for the development of an intelligent stealth platform and its antenna applications.

Microwave photonic multi-frequency reconfigurable PSK/ASK/FSK formats modulation signals generation

We report a novel photonic approach to generate reconfigurable multi-frequency multiple binary modulation formats microwave signals based on a dual-polarization dual-drive Mach-Zehnder modulator (DPol-DDMZM). Two radio frequency (RF) signals and two electrical coding signals are applied to the modulator. By simply setting the proper formats of the applied coding signals, multi-frequency phase shift keying (PSK), amplitude shift keying (ASK) and frequency shift keying (FSK) microwave signals can be generated successfully. Our proposed scheme has been theoretically analyzed and experimentally demonstrated. The tunability of the bit rates and center frequencies of the system has been also proved. No polarization controller (PC) or polarizer (Pol.) is involved, resulting in the independent polarization of the system. Compared with previous reports of single-frequency PSK/ASK/FSK format microwave signals generation system, our proposed simple and compact system realizes multi-frequency reconfigurable functions without the necessity of changing system structure, which can bring great potential application in the multi-frequency radar and communication systems.

Learning‐Effective Mixed‐Dimensional Halide Perovskite QD Synaptic Array for Self‐Rectifying and Luminous Artificial Neural Networks

AbstractA mixed‐dimensional heterostructure comprising nanomaterials with varying dimensions provides a promising structure for an artificial synapse for reconfigurable neuromorphic functions. In this study, an 8 × 8 memristor crossbar array based on a mixed‐dimensional heterostructure comprising Cs1−xFAxPbBr3(0.00 ≤ x ≤ 0.15) quantum dots (QDs) and different dimensional interfacial nanomaterial layers between the Al and ITO electrodes is designed and fabricated. This array device exhibits a high yield and reliable self‐rectifying analog switching characteristics with low synaptic‐coupling (SC, up to 5.19 × 10−5) and light emission, facilitating stimuli response visualization and preventing undesired pathways in the network array. Furthermore, because the formamidinium (FA) concentration alters the QD size, thereby engineering interfacial band alignment in the heterostructure, the essential synaptic properties such as dynamic range, SC, and nonlinearity can be improved. Especially, asxincreases from 0 to 0.11, the recognition accuracy for the MNIST patterns increases significantly, from 68.97% to 89.08%, even for single‐layer ANNs. The energy consumption required for a specific accuracy level is reduced by a factor of 25.15. The utilization of mixed‐dimensional perovskite QD‐based heterostructures in neural networks may provide desirable neuromorphic electronic functions with enhanced learning capability and energy efficiency, while preventing unwanted neural signals.

Environment‐Adaptive Meta‐Channel

AbstractThe fundamental transmission channels of smart wearable devices and systems should support function reconfiguration and environment cognition or self‐adaption. Here, a environment‐adaptive meta‐channel (EAMC) is proposed that is adaptive to the near‐field environment. Benefiting from the capability to manipulate environment‐wave interactions, EAMC can cognize the near‐field environment impurities with subwavelength resolution, in which different impurities can be distinguished and located accurately with the aid of machine learning method. Thus, EAMC can adapt itself to varying environment so that its customized function is stabilized. For instance, EAMC is used as a communication modulator to adapt to different dielectric impurities and human body contacts dynamically. The quality of transmitted picture signals with impurities will deteriorate seriously but can be repaired efficiently as the self‐adaptive process of EAMC is used. Hence, the proposed EAMC could be a candidate for fundamental transmission channels for future smart wearable devices and systems.

A highly integrated nonvolatile bidirectional RFET with low leakage current

A highly integrated nonvolatile bidirectional reconfigurable FET controlled by a single gate (SGCN-BRFET) is proposed. The nonvolatile function, the bidirectional function and the reconfigurable function can be achieved at the same time. Instead of the independently powered program gate (PG) of BRFET, the program operation of the proposed SGCN-BRFET can be independently completed by the control gate (CG) itself through storing positive or negative charges in a floating program gate (FPG) formed on both source/drain sides. Thereafter, the interconnection can be simplified. The conduction type of the SGCN-BRFET is reconfigured by programming the FPG with different type of charges into the FPG. By optimizing the quantities of the stored charges, the FPG effective voltage can be changed to achieve higher forward current and lower leakage current. The physical mechanism of the proposed SGCN-RFET has been systematically analyzed. The device performance has been compared with BRFET. The influence of the amount of charge to the device performance has also been discussed in detail.

Programmable Data Plane Applications in 5G and Beyond Architectures: A Systematic Review.

The rapid evolution of 5G and beyond technologies has sparked an unprecedented surge in the need for networking infrastructure that can deliver high speed, minimal latency, and remarkable flexibility. The programmable data plane, which enables the dynamic reconfiguration of network functions and protocols, is becoming increasingly important in meeting these requirements. This paper provides an overview of the current state of the art in programmable data planes implemented in 5G and beyond architectures. It proposes a classification of the reviewed studies based on system architecture and specific use cases. Furthermore, the article surveys the primary applications of programmable devices in emerging telecommunication networks, such as tunneling and forwarding, network slicing, cybersecurity, and in-band telemetry. Finally, this publication summarizes the open research challenges and future directions. In addition to offering a comprehensive review of programmable data plane applications in telecommunication networks, this article aims to guide further research in this promising field for network operators and researchers alike.

RECO-ASCON: Reconfigurable ASCON hash functions for IoT applications

The need for reconfigurable lightweight cryptographic processors with low power consumption for securing the Internet of Things (IoT) with adaptive functionalities is getting attracted due to security properties, such as data fidelity, provenance, and privacy concerns. This paper presents RECO-ASCON, a reconfigurable security processor that supports both cryptographic Hash and Hasha ASCON algorithms. The proposed design is implemented in Chisel hardware construction language, an open-source hardware library. It has been evaluated in various hardware platforms such as FPGAs, embedded systems and ASICs with various technology nodes and design flows. In the PYNQ-Z1 board, RECO-ASCON can be mapped to five processors in total with a Micro-Blaze soft-core processor for streaming data to all of them while running at 200MHz without producing any timing violations. Moreover, mapping the proposed RECO-ASCON processor on the Nexsys4-DDR Xilinx Kit (ARTIX-7 chip) would cost ∼ two times fewer resources and run 1.25 × faster than the existing implementation of just one of the ASCON hash functions on the same family of the chip. We implement the proposed processor in 28 nm industry technology with commercial design flow, it achieves a maximum frequency of 1.12 GHz while achieving highest energy efficiency compared to the state-of-the-art implementations. The total area is only 9170.82um2 in 28 nm. To further evaluate the design, we also implement it with all open-source design tools and process technology libraries in 45 nm, it achieves 1 GHz maximum frequency and consumes only 18225um2 in 45 nm. Overall, the proposed reconfigurable processor is compact and more energy efficient, making it a perfect candidate to be deployed in wide range of IoT systems.

Spin dynamics, loop formation and cooperative reversal in artificial quasicrystals with tailored exchange coupling

Aperiodicity and un-conventional rotational symmetries allow quasicrystalline structures to exhibit unusual physical and functional properties. In magnetism, artificial ferromagnetic quasicrystals exhibited knee anomalies suggesting reprogrammable magnetic properties via non-stochastic switching. However, the decisive roles of short-range exchange and long-range dipolar interactions have not yet been clarified for optimized reconfigurable functionality. We report broadband spin-wave spectroscopy and X-ray photoemission electron microscopy on different quasicrystal lattices consisting of ferromagnetic Ni81Fe19 nanobars arranged on aperiodic Penrose and Ammann tilings with different exchange and dipolar interactions. We imaged the magnetic states of partially reversed quasicrystals and analyzed their configurations in terms of the charge model, geometrical frustration and the formation of flux-closure loops. Only the exchange-coupled lattices are found to show aperiodicity-specific collective phenomena and non-stochastic switching. Both, exchange and dipolarly coupled quasicrystals show magnonic excitations with narrow linewidths in minor loop measurements. Thereby reconfigurable functionalities in spintronics and magnonics become realistic.

Non-volatile reconfigurable spin logic functions in a two-channel Hall bar by spin–orbit torque-based magnetic domains and directional read current

A long-standing goal of CMOS-based logic devices is to meet the needs of key markets, including ultralow-power operation and high operation speed, along with the continuing miniaturization of the architecture. However, despite significant progress in their development, conventional CMOS-based devices still suffer from drawbacks such as introducing large unintended leakage currents and volatile behavior. Thus, reconfigurable logic gates based on magnetic domain (MD) have emerged as a highly promising option because they offer fast operation speeds, nonvolatility, and diverse logic functions in a single-device configuration. Here, we address multiple reconfigurable MD logic gates in a single two-channel Hall bar device by varying the voltage-driven read-current directions and selecting a non-inverting or inverting comparator in W/CoFeB/MgO/Ta stacks. The non-volatile MD switching behavior induced by spin–orbit torque significantly affects our logic gate functions, which are not necessarily synchronized to a single clock. By adapting MD switching by spin-orbit torque and anomalous Hall effect voltage outputs, we identified eight reconfigurable logic gates, including AND, NAND, NOR, OR, INH, Converse INH, Converse IMP, and IMP, in a single device. These experimental findings represent a significant step forward in a wide range of MD-based logic applications in the near future.

ReAFM: A Reconfigurable Nonlinear Activation Function Module for Neural Networks

Deep neural networks (DNNs) with various nonlinear activation functions (NAFs) have achieved unprecedented successes, sparking interest in efficient DNN hardware implementation. However, most existing NAF implementations focus on one type of functions with dedicated architectures, which is not suited for supporting versatile DNN accelerators. In this brief, based on a proposed reciprocal approximation optimization (RAO) method, an efficient reconfigurable nonlinear activation function module (ReAFM) is devised to implement various NAFs. The computational logic and dataflow of certain NAFs are merged and reused to minimize hardware consumption by leveraging the correlations among different NAFs. In addition, a precision adjustable exponential unit (PAEU) is developed to obtain a good tradeoff between the approximation accuracy and hardware cost. Compared to the prior art, the experimental results demonstrate that the proposed ReAFM can support many more NAF types with comparable or even better performance. Furthermore, evaluation results on some prevalent neural networks show that the proposed approximation method causes negligible accuracy loss (< 0.1%).

FSEAD: A Composable FPGA-based Streaming Ensemble Anomaly Detection Library

Machine learning ensembles combine multiple base models to produce a more accurate output. They can be applied to a range of machine learning problems, including anomaly detection. In this article, we investigate how to maximize the composability and scalability of an FPGA-based streaming ensemble anomaly detector (fSEAD). To achieve this, we propose a flexible computing architecture consisting of multiple partially reconfigurable regions, pblocks, which each implement anomaly detectors. Our proof-of-concept design supports three state-of-the-art anomaly detection algorithms: Loda, RS-Hash, and xStream. Each algorithm is scalable, meaning multiple instances can be placed within a pblock to improve performance. Moreover, fSEAD is implemented using High-level synthesis (HLS), meaning further custom anomaly detectors can be supported. Pblocks are interconnected via an AXI-switch, enabling them to be composed in an arbitrary fashion before combining and merging results at runtime to create an ensemble that maximizes the use of FPGA resources and accuracy. Through utilizing reconfigurable Dynamic Function eXchange (DFX), the detector can be modified at runtime to adapt to changing environmental conditions. We compare fSEAD to an equivalent central processing unit (CPU) implementation using four standard datasets, with speedups ranging from 3× to 8×.

Vanadium dioxide based bifunctional metasurface for broadband absorption and cross-polarization conversion in THz range

Achieving switchable and reconfigurable functions based on a single metasurface has become one of the research hotspots among scholars in recent years. Based on the excellent phase transition properties of vanadium dioxide (VO2), a THz bifunctional metasurface device (BMD) is designed that can realize broadband absorption and broadband cross-polarization conversion. When VO2 behaves in the metallic state, the BMD acts as a broadband metamaterial absorber (MA), and its absorbance is larger than 90 % in the range of 1.97–4.63 THz with a relative bandwidth (RB) of 80.61 %. In addition, the MA is insensitive to the polarization angle and can maintain high absorbance over a wide range of incident angles for both y- and x-polarized THz waves. When VO2 behaves in the insulated state, the BMD will act as a broadband linear polarization converter (PC). It has a polarization conversion ratio (PCR) of greater than 90 % with a RB of 92.31 % in the frequency range of 1.54–4.18 THz. The excellent absorption and polarization conversion characteristics of the proposed BMD make it possess potential values in different THz areas with sub-wavelength device scales.

Complementary Doped Source-Based Reconfigurable Schottky Diode as an Equivalence Logic Gate.

A complementary doped source-based reconfigurable Schottky diode (CDS-RSD) is proposed for the first time. Unlike other types of reconfigurable devices that have source and drain (S/D) regions with the same material, this has a complementary doped source region as well as a metal silicide drain region. Compared to three-terminal reconfigurable transistors, which have both the program gate and control gate, the proposed CDS-RSD does not have a control gate but only a program gate for reconfiguration operation. The drain electrode of the CDS-RSD is not only the output terminal of the current signal but also the input terminal of the voltage signal. Therefore, it is a reconfigurable diode based on high Schottky barriers for both the conduction band and valence band of silicon, which formed on the interface between the silicon and drain electrode. Therefore, the CDS-RSD can be regarded as the simplification of the reconfigurable field effect transistor structure on the premise of retaining the reconfigurable function. The simplified CDS-RSD is more suitable for the improvement of logic gate circuit integration. A brief manufacture process is also proposed. The device performance has been verified through device simulation. The performance of the CDS-RSD as a single-device two-input equivalence logic gate has also been investigated.

A reconfigurable dual‐band low noise amplifier for 5G in 65‐nm CMOS

AbstractIn this paper, a reconfigurable low noise amplifier (LNA) is proposed for 5G dual‐bands in a 65‐nm CMOS process. The reconfigurable function of LNA is realized by designing reconfigurable matching networks composed of transformers and MOS transistor switches. The pole characteristics of the resonant network composed of the reconfigurable network and the equivalent circuit of the amplifying device are deduced and analyzed in detail. By establishing the relationship between two reconfigurable frequencies and the ratio of transformer coil inductance under two switching states, the position of the switch and the specific parameters of the reconfigurable matching network are determined. Measurement results show small‐signal gain of 25.5 to 33.9 dB and noise figure of 3.3 to 4.3 dB at 24 to 29.5 GHz bands, and small‐signal gain of 23.5 to 27.8 dB and noise figure of 4.3 to 4.5 dB at 37 to 40 GHz bands, respectively. The chip area occupied 0.34 mm2 including pads.

Reconfigurable Logic-in-Memory Computing Based on a Polarity-Controllable Two-Dimensional Transistor.

Logic-in-memory architecture holds great promise to meet the high-performance and energy-efficient requirements of data-intensive scenarios. Two-dimensional compacted transistors embedded with logic functions are expected to extend Moore's law toward advanced nodes. Here we demonstrate that a WSe2/h-BN/graphene based middle-floating-gate field-effect transistor can perform under diverse current levels due to the controllable polarity by the control gate, floating gate, and drain voltages. Such electrical tunable characteristics are employed for logic-in-memory architectures and can behave as reconfigurable logic functions of AND/XNOR within a single device. Compared to the conventional devices like floating-gate field-effect transistors, our design can greatly decrease the consumption of transistors. For AND/NAND, it can save 75% transistors by reducing the transistor number from 4 to 1; for XNOR/XOR, it is even up to 87.5% with the number being reduced from 8 to 1.

A nonvolatile bidirectional reconfigurable FET based on S/D self programmable floating gates.

A nanoscale nonvolatile bidirectional reconfigurable field effect transistor (NBRFET) based on source /drain (S/D) self programmable floating gates is proposed. Comparing to the conventional reconfigurable field effect transistor (RFET) which requires two independently powered gates, the proposed NBRFET requires only one control gate. Beside, S/D floating gates are introduced. Reconfigurable function is realized by programming different types of charges into the S/D floating gates through biasing the gate at a positive or negative high voltage. The effective voltages of the S/D floating gates are determined jointly by the quantity of the charge stored in the S/D floating gates and the gate voltage. In addition, the charge stored in the floating gate has an effect of reducing the energy band bending near the source/drain regions when the gate is reversely biased, thereafter, the band to band tunneling (BTBT) leakage current can be largely decreased. The scale of the proposed NBRFET can be reduced to nanometer level. The device performances such as the transfer and output characteristics are verified by device simulation, which proves that the proposed NBRFET has very good performance in the nanometer scale.

A flexible pressure sensor with interference immunity capability

PurposeFlexible pressure sensor arrays have promising applications in analog haptics, reconfiguration of sensory functions, artificial intelligence, wearable devices and human-computer interaction. The force disturbance generated by the connecting material between the sensor array units will reduce the detection accuracy of the unit. The purpose of this paper is to propose a flexible pressure sensor with interference immunity capability. A C-type bridge flexible piezoelectric structure is used to improve the pressure perturbation. The interference immunity capability of the sensor has been improved.Design/methodology/approachIn this paper, a C-type pressure sensor array structure by rapid injection moulding is manufactured through the positive piezoelectric effect of a piezoelectric material. The feasibility of C-type interference immunity structure in a flexible sensor array is verified by further analysis and experiment. A flexible pressure sensor array with C-type interference immunity structure has been proposed.FindingsIn this paper, we present the results of the perturbation experiment results of the C-type pressure sensor array, showing that the perturbation error is less than 8%. The test of the flexible sensor array show that the sensor can identify the curved angle of up to 120 °, and the output sensitivity of the sensor in the horizontal state reaches 0.12 V/N, and the sensor can withstand the pressure of 80 N. The flexible sensor can work stably in the stretch rate range of 0–8.6% and the stretch length range of 0–6 mm.Originality/valueIn this paper, C-type pressure sensor array structure is fabricated by rapid injection moulding for the first time. The research in this paper can effectively reduce the disturbance of input pressure on the sensor’s internal array and improve the output accuracy. The sensor can intuitively reflect the number of fingers sliding on the sensor by the order in which the maximum voltage appears. Due to the strong interference immunity capability and flexibility of the flexible sensor array mechanism, it has a broad application prospect in the practical fields of haptic simulation, perceptual function reconstruction, artificial intelligence, wearable devices and human–computer interaction.

Modular Design for Versatile Broadband Polarizing Metasurfaces with Freely Switching Functions

AbstractPolarization is a fundamental property of electromagnetic waves that plays a key role in many physical phenomena and applications. Schemes to manipulate it are revisited with the emergence of metasurfaces, which have brought multi‐functionalities straightforwardly. However, this has come at the expense of design complexity that relies strongly on field theory. Here, an ingenious strategy of modular design is proposed to construct subwavelength multifunctional polarization control devices. Chiral metasurfaces with different handedness are first proposed and regarded as modules. The versatile polarization controller can thus be obtained with the combination of different modules. These experiments demonstrate that the well‐designed polarization controller possesses reconfigurable functionality, and various broadband polarization and amplitude regulation functions with high efficiency including arbitrary linear polarization rotation, asymmetric transmission effect, neutral‐density‐like filter, polarization beam splitter, etc., can be readily realized just by changing the cascaded modules. The physical mechanisms of the versatile polarization controller and chiral metasurface modules are both guaranteed by the Fabry–Pérot‐like resonances, which are theoretically verified via the transfer matrix method. It is envisioned that the modular concept will be of great benefit to designing compact multifunctional polarization controllers.