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Limitations in current fuel cell technology lead to instability in output voltage for hydrogen fuel cells, particularly under the influence of temperature variations and fuel flow fluctuations, thereby affecting the normal operation of hydrogen-powered vehicles. Improving the motor drive control system and optimizing energy management are crucial for enhancing overall vehicle performance. To improve dynamic response speed while suppressing harmonics, this paper proposes a predictive control strategy for high-speed permanent magnet synchronous motors with LCL filter in hydrogen fuel cell electric vehicles. The proposed control strategy suppresses high-frequency current harmonics by sampling only the current on the motor side, enabling fast predictive control of the high-order system motor-side current. Additionally, to mitigate the issue of unstable torque output of the electric motor at low fuel levels, this paper proposes a new composite predictive torque trajectory control strategy based on the previous control strategy. This strategy ensures rapid and accurate tracking of motor output torque, particularly during decreases in fuel cell output voltage. Experimental results validate the feasibility and effectiveness of the proposed control strategies in this paper. • Torque stability control of hydrogen electric vehicle under low fuel state. • Predictive current direct control for LCL-equipped high-speed PMSM drive based on single-sensor. • A composite predictive current trajectory control strategy balancing small steady-state error and fast dynamic response. [ABSTRACT FROM AUTHOR]

The escalating demand and complexity of monitoring services handled by Network Operations Centers (NOCs) have led Mobile Network Operators (MNOs) to prioritize automated solutions for network fault detection and diagnosis. Consequently, various Machine Learning (ML)-based Root Cause Analysis (RCA) systems have been developed, however their lack of explainability poses a challenge due to the predominantly black-box nature of ML models. This paper addresses this issue by presenting a supervised clustering methodology capable of integrating both glass-box and black-box models, the latter complemented by post-hoc explainability techniques. While black-box models excel in predictive capabilities, necessitating post-hoc techniques for explainability, glass-box models prioritize transparent decision-making, fostering a clearer understanding of the model's behavior. This work delineates a methodology for performing RCA of faults in the User Downlink (DL) Average Throughput Key Performance Indicator (KPI), simultaneously comparing the performance of black-box models (Light Gradient-Boosting Machine (LightGBM) and Extreme Gradient Boosting (XGBoost)) with glass-box models (Logistic Regression (LR) and Explainable Boosting Machine (EBM)). Results revealed that the LightGBM black-box algorithm coupled with the SHapley Additive exPlanations (SHAP) method demonstrated superior performance in fault detection and diagnosis, without compromising the overall explainability. Consequently, it was possible to identify faults related to radio conditions, low network usage in specific user groups, low network capacity, and mobility issues. The paper concludes with practical mitigation strategies for each identified fault cluster. • Supervised clustering detects and diagnoses critical mobile network KPI failures. • LightGBM + SHAP outperformed other models in detecting User DL THP faults. • The methodology diagnosed User DL faults as radio, usage, capacity, and mobility. [ABSTRACT FROM AUTHOR]

During the design of a Doherty power amplifier (DPA), the phenomenon of peaking PA turning on in advance is commonly observed. This is mainly due to the feedback of the main PA signal to the gate of the peaking PA through the gate-drain feedback capacitor, which results in an increase in its gate voltage. As a result, the overall efficiency of the back-off region is significantly reduced. This paper first describes the phenomenon of peaking PA turning on in advance. The formula for the voltage (referred to as the feedback gate voltage, FGV) imposed on the gate of the peaking PA by the main PA signal is then deduced. On this basis, the FGV is analysed numerically. For verification, an asymmetric DPA with a 9 dB output back-off (OBO) power level is designed and fabricated in this paper using GaN CGH40010F and CGH40025F transistors. According to the measurement results, the saturated drain efficiency of the DPA is 53.5%–63.3% in the 0.75–1.25 GHz band, the efficiency at the 9 dB OBO level is between 45.5%–54%, and the saturated output power is between 45 dBm–45.7 dBm, with a saturation gain of more than 8 dB. [ABSTRACT FROM AUTHOR]

This paper presents a 39-GHz broadband image-rejection down-conversion mixer for 5G millimeter-wave (mmWave) communication. To achieve a broadband image rejection, this paper proposes an on-chip compact transformer-based image-rejection filter, which exhibits the ability to track the pole and zero frequencies simultaneously. Moreover, the working mechanism and design guideline of the transformer-based image-rejection filter are illustrated with theoretical analysis, simulations and measurements. To enhance the mixer linearity performance, the transconductance stage of the conventional Gilbert mixer is utilized as a current source, and the radio frequency (RF) signal is directly fed into the switching stage. Fabricated in a 65-nm CMOS process, using a single-stage image-rejection filter with a compact area of only 0.013 mm2, the measurement results show that the proposed down-conversion mixer achieves a gain of 0 dB, a 3-dB RF bandwidth from 34 to 42 GHz, an input 1-dB compression point (IP 1dB) of 5.6 dBm, and an image rejection ratio (IRR) of about 25 dBc. [ABSTRACT FROM AUTHOR]

Carbon nanotube FET (CNFET) technology emerges as a promising replacement for MOS technology, offering novel circuit design capabilities with its multi-threshold voltage feature. This paper introduces a novel Schmitt trigger designed based on multi-threshold voltages, allowing direct and precise adjustments of VTL (lower threshold voltage) and VTH (higher threshold voltage) through two external control voltages. The VTL and VTH are nearly equal to these external voltages. These features result in the introduction of two new circuits for nanotechnology in this paper: the hardware implementation of the Hysteresis quantizer and the implementation of the voltage-to-period converter (V2P) circuit. Simulation results using Hspice software and the Stanford 32 nm library show that the proposed circuit exhibits considerable linear control ability, with a 49 % PDP improvement compared to other designs. Additionally, the first hardware implementation of the Hysteresis quantizer in nanoelectronics and the voltage-to-period converter demonstrate proper operation, marking a significant milestone. [ABSTRACT FROM AUTHOR]

Ad-hoc sensor networks (known also as citizen or resident networks) are gaining in popularity. They tend to utilize inexpensive sensors; they are deployed and operated in ad-hoc, opportunistic manner, consequently often delivering results of higher uncertainty. Reputation-based algorithms are used for data reconstruction to contain the input of faulty, or unreliable, nodes on the network. This paper discusses the question whether it is feasible to introduce high quality, expensive reference nodes to the network to significantly decrease its uncertainty, in situations where the reconstruction algorithm run by the network is not altered. This paper uses five leading cases, subsequently analyzed with the help of a simulator that executes the reputation-based EWMA algorithm. It identifies that the simple introduction of reference nodes alone does not help in addressing uncertainty without making alteration to the algorithm or to the design of the network. [ABSTRACT FROM AUTHOR]

This paper proposes a narrowband near-field (NF) source localization algorithm based on two correlation operations. By utilizing the correlation of incident signal in the time and spatial domains, the algorithm achieves direction-of-arrival (DOA) with high-precision and low-complexity and range estimation under the virtual single snapshot. To do so, in the processing of NF source received signals, this paper first utilizes the symmetry of the cross-cross array and obtains a covariance matrix containing only azimuth and elevation information through two correlation operations. Since the covariance matrix has a standard two-level Toeplitz matrix form, the estimated parameters can be directly extracted from the noise-free covariance matrix without pairing using the two-level Vandermonde decomposition technique. Finally, the estimated value of the range is obtained using a one-dimensional (1-D) spectral peak search. Computer simulation results verify the superior performance of the proposed algorithm in terms of complexity and estimation accuracy. [ABSTRACT FROM AUTHOR]

This paper discusses the synthesis of a steerable frequency-invariant radiation pattern for broadband scalable antenna arrays (SAAs). The proposed method allows to achieve constant beamwidth and beam direction over a 3 : 1 bandwidth and is based on an appropriate radiating elements' placement in the SAA and a proper amplitude and phase excitation of the array. Both amplitudes and phases of signals exciting the radiating elements are varied with frequency to ensure the radiation pattern invariance. Additionally, the paper proposes solutions to problems occurring in SAAs i.e., the problem of overlapping radiating elements and the problems of sidelobe and grating lobe reduction. To verify the proposed synthesis method, a set of radiating elements, which operate over a 3 − 9 GHz frequency range, has been manufactured and measured. The overall radiation pattern of the antenna array has been obtained by a summation of the radiation patterns produced by each of the radiating elements. • Synthesis of a steerable frequency-invariant radiation pattern. • Methods for grating lobe and side lobes reduction. • Solution to the overlapping radiating elements problem. [ABSTRACT FROM AUTHOR]

This paper presents the design of a self-image-guided ultrasonic (SIG-US) transceiver for reliable wireless power transmission (WPT) to miniaturized biomedical implants. In the receiver (RX) mode, this paper proposes a method for high precision time interval measurement (TIM) between two signals independent of their amplitudes. In the transmitter (TX) mode, a 15 V Class-DE driver by stacking 3.3 V transistors of 180 nm standard CMOS technology is designed to drive a 32-element linear array. The designed TX efficiency is 90.93%. The post-layout and the Matlab k-Wave toolbox simulation results show that the designed system is capable of transmitting power to the implant with less than 0.9% reduction compared to the ideal SIG-US system over the ± 45 ° steering range. Considering the mismatch effect between transistors, the power reduction is less than 2% in the worst case. The RX with a power consumption of 628.83 μ W from a nominal supply voltage of 1.8 V, is capable of detecting time delays between two signals over the input range of 1 mV to 10 mV, with high accuracy. [ABSTRACT FROM AUTHOR]

Single-phase string inverter has been widely applied to grid-tied photovoltaic (PV) rooftop applications for its renewable energy. However, the inherent attribute of intermittency in solar energy may induce instability and unqualified power. To meet the grid-interconnection standards, high demands of efficiency and harmonic distortion need to be imposed on DC/AC inverters. Conventional soft-switching inverters used to sacrificing auxiliary resonant circuits to exchange for soft switching. This requires additional costs as well as sufficient dead time to discharge junction capacitances of all switches, which exacerbates total harmonics distortion (THD) induced by dead-time effect. To improve, this paper proposes a partial soft-switching silicon carbide (SiC) -based active neutral-point-clamped (ANPC) inverter, which possesses high efficiency, eligible dead time, and no auxiliaries. 650-V SiC MOSFET is adopted for its smaller output capacitance compared with Si device. Hybrid PWM modulation is utilized to achieve partial soft switching. Whereas, the soft switching realization range and power losses highly depend on the dead time. To achieve less power loss and improved dead time effect, this paper proposes a loss model-based dead time algorithm through a Power Loss VS. Dead Time mathematical loss model. Moreover, the mechanism of the dead time affected by soft switching is explored. The transition modes, dead time configurable boundaries, and design procedure are also analyzed in detail. A 1-kW prototype is demonstrated with the input of 800 V and the rated output of 220 V/ 4.5 A. Its efficiency could reach 99.6% with THD=0.95% at full power level. [ABSTRACT FROM AUTHOR]

In a phase-locked loop (PLL), a high reset pulse width in the phase frequency detector (PFD) and current mismatches in the charge pump (CP) are the major contributors to a high reference spur in a clock. This paper presents a novel replica technique based dead zone free PFD to reduce the reset pulse and a self-cascode current-splitting CP to reduce current mismatch. The proposed PFD and CP are designed using the UMC 180 nm CMOS process. The proposed PFD achieves a reset pulse width of 113 ps. The CP is designed for a CP current of 100 μ A. It has an output voltage range of 0.4 V–1.2 V, with a current mismatch of 1.3%. A PLL with the proposed PFD+CP achieves a reference spur that is 39.5% lower than the reference spur of the PLL with conventional PFD+CP. The proposed PFD+CP consumes 0.28 mW power in the locked stated. The layout area consumed by the proposed PFD+CP is 46 × 75 μ m 2 . • The reference spur in a PLL is minimised in this paper. • The reset pulse width of the phase frequency detector (PFD) is reduced. • The current mismatch of the charge pump (CP) is decreased. • A novel replica technique based dead zone free PFD is proposed. • To reduce the reset pulse width of the PFD, replica technique is adopted. • A self-cascode current-splitting CP is proposed. • To reduce current mismatches in the CP, self-cascode current-splitting technique is used. [ABSTRACT FROM AUTHOR]

In this paper, to investigate the problem of radio wave propagation in complex environments, a new algorithm is proposed based on the equivalence principle algorithm and the domain decomposition method to rapidly and accurately predict electromagnetic scattering and radio wave propagation in half-space. First, equivalent surfaces are introduced to decompose the obstacle region and replace the scattering effect of obstacles within the equivalent surfaces with equivalent input and output electromagnetic currents. Then, the operator S, representing the relationship between the input and output equivalent electromagnetic currents on the equivalent surfaces, and the operator T, representing the interactions between the equivalent electromagnetic currents on each equivalent surface, are derived; this allows the calculation process of the overall spatial field in a complex environment to be simplified to the iterative calculation process of operators S and T. To reduce the complexity of calculating S, a neural network embedded with physical information is introduced to replace the calculation process. Finally, the training results are applied to an example and compared with the theoretical numerical results yielded by the method of moments in different cases with obstacles. The results reveal that the new method proposed in this paper is highly accurate and achieves a substantial improvement in calculation speed. Therefore, our proposed algorithm provides a new and reliable method for calculating the spatial field in complex environments. • The EPA is introduced to use equivalent surfaces to replace the scattering inside it. • The operators S and T are introduced into the process of solving the field. • A neural network with physical information embedded is applied to calculate the S. • Random undulating terrains are generated by Karhunen–Loève expansion. • MoM providing a good foundation for training is used to generate dataset. [ABSTRACT FROM AUTHOR]

As transistors shrink in size, the integration density of memory circuits like Static Random Access Memory (SRAM) cells rises, making them increasingly susceptible to Single Event Effects (SEE). In the space environment, memory circuits face stability and reliability challenges due to the presence of various charged particles such as α-particles, neutrons, electrons, heavy ions, and photons. These high-energy particles create ion tracks when they strike the memory device, leading to upsets in the storage bits. Conventional 6 T SRAM cells are susceptible to these upsets. As a solution this paper proposes a new Radiation Tolerable (RT 13 T) SRAM cell that is better suited for deep-space applications compared to other memory cell. RT13T has been validated to withstand radiation hazards through Critical Charge (Q Crit) analysis, which shows that it exhibits 1.17×, 1.1×, 1.94× and 1.06× highest Q Crit than QUCCE 10 T/12 T,traditional 6 T and LIOR 13 T memory cells, respectively. As the comparison made, our Proposed RT 13 T saved by5.1 %,9.9 %, 20.1 % and 7 % of the power consumption compared to QUCCE10T/12 T/LIOR 13 T/SERSC-16 T SRAM cells at a nominal supply voltage of 0.7 V. It also exhibits shorter read delay (T RA) 10.6 %, 1.34 %, 9.6 %, 22.16 %compared to QUCCE 10 T/12 T,6T, SERSC-16Tmemory cells, respectively. In terms of stability,our proposed RT13T SRAM cell exhibits 2.32×/2.05×/2.9×/1.05×/1.01 × higher read stability as compared with QUCCE10T/12 T/6T/LIOR 13 T/SERSC-16 T memory cells during the read operation. The our proposed RT13T shows improvements in design metrics are at the expense of a longer write delay. To characterize the performances of the proposed RT13T, 16-nm CMOS predictive technology model and validated through extensive simulation with licensed PrimeSim HSPICE of Synopsys. The results of our proposed RT13T cell are compared with some other previously proposed memory cells such as 6 T, QUCCE 10 T, QUCCE 12 T, LIOR 13 T and SERSC-16 T memory cells. The obtained results are tabulated and plotted for graphical analysis. In terms of area consumption our proposed 13 T consumes 0.9×/0.6 × lesser area than QUCCE 12 T/SERSC-16 T memory cells but our proposed circuit consumes 3.1×/1.08×/1.05 × more area than QUCCE10T/conventional 6 T/LIOR 13 T because QUCCE10T and 6 T consist of less number of transistors in memory cells.The cell proposed in this paper demonstrates strong radiation-hardened capabilities and excellent overall performance, making it well-suited for aerospace electronic devices and ensuring stable operation in space radiation environments. [ABSTRACT FROM AUTHOR]

This paper presents and compares the implementation of a digital predistortion (DPD) linearizer for radiofrequency power amplifiers (PAs) considering two different hardware acceleration platforms. Both graphics processing unit (GPU)-based and field programmable gate arrays (FPGA)-based implementations of the DPD are capable to meet the high throughput requirements for linearizing the PA with current 5G new radio (NR) wideband signals. A comparison in terms of hardware resources usage, precision, throughput and linearization performance is provided for both GPU and FPGA implementations of a DPD based on the generalized memory polynomial (GMP) behavioral model. [Display omitted] • This paper focuses on the implementation of the GMP DPD model in both FPGA and GPU. • A trade-off among precision, resources usage and throughput performance is given. • The DPD performance is validated with a SLMBA with a hardware-in-loop test setup. [ABSTRACT FROM AUTHOR]

The problem addressed in this work is the enhancement of energy efficiency in buildings, primarily focused on heating control. The paper highlights the importance of addressing this challenge, given that HVAC systems are responsible for over 60% of total energy consumption in buildings, making them the largest energy consumers in both the residential and nonresidential sectors. This paper presents a methodology for developing a model predictive control (MPC) system based on artificial neural network (ANN) models, with the aim of improving the energy efficiency of buildings. This approach involves the creation of a training dataset using dynamic thermal simulation tools, enabling the learning of the ANN model that is responsible for predicting future states within an MPC optimization loop. Additionally, the implementation leverages advanced technologies such as Field-Programmable Gate Arrays (FPGAs), specifically the PYNQ board, Wi-Fi modules, and MQTT communication to enhance scalability, deployment, and adaptability. The study evaluates the proposed Neural Network Model Predictive Control (NNMPC) strategy implemented on the PYNQ, reporting a substantial reduction of 38.53% in heating energy consumption in buildings compared to a basic On/Off control approach for 24-hour simulation. This outcome underscores the solutions significant potential for energy savings in building heating systems. [ABSTRACT FROM AUTHOR]

This paper describes the optimal design and analysis of compact multiband Hybrid Fractal Antenna using Invasive Weed Optimization (HFAIWO). The configured structure involves the fusion of Minkowski, Sierpinski carpet and Giuseppe Peano in a coherent manner. The two-iterative conglomerated fractal antenna is realized physically by considering FR4 epoxy material (dielectric constant, ε r = 4.4 and mass density = 1,900 kg/m3). The volumetric dimensions of the fabricated prototype are 36 x 36 x 1.6 mm3. In the designing process, the geometrical descriptors, namely, feedline width 'W F ' and ground plane dimension 'L G ' are optimized specifically using Invasive Weed Optimization (IWO) and Harmony Search Algorithm (HSA) strategies. The optimal solution is searched by changing the descriptor values under a set of practical constraints. The examined values of 'W F ' and 'L G ' using IWO and HSA are 3 and 31 mm, and 2.6 and 28.7 mm, respectively. Comparative results reveal that IWO offers superior solution quality and convergence than HSA. Afterwards, experimentation of the Projected HFAIWO is done to justify the recommended fractal hybridization approach. Measurements reveal that for VSWR ≤ 2, the fabricated structure produces nine resonance points (1.84, 3.99, 5.15, 5.55, 6.30, 6.58, 8.00, 9.29, and 12.01 GHz) with appreciable gain values. At the respective resonance points, the −10 dB impedance bandwidth is 3.9 %, 3.1 %, 2.1 %, 2.2 %, 1.4 %, 1.2 %, 6.9 %, 1.2 %, and 12.23 %. The provided radiation patterns are arbitrary bidirectional/omnidirectional. By applying the above-said approaches, the radiator size is reduced by 54 %. Importantly, the constructed structure covers two important bands i.e. 1.84 GHz (GSM 1800 band, downlink) and 5.55 GHz (WLAN (Lower) 5.150–5.725 GHz) associated with energy harvesting applications. The practical outcomes suggest that the introduced prototype is a proficient candidate for energy harvesting systems, Satellite communication for downlink, Long range tracking, Battlefield surveillance, Digital broadcast satellite service, Weather Radar, and Maritime navigation radar. [ABSTRACT FROM AUTHOR]

This paper presents an LDO design tailored to the various power domains of CPUs. In contemporary CPU designs, different functional modules typically necessitate distinct voltage levels, thus requiring a flexible and adjustable power management approach. An LDO with an internally compensated super source follower (SSF) and a multi-zero-pole compensated loop stability is proposed. The SSF is used to reduce the output impedance of the LDO, enhancing its carry-under-load capability. The loop is then transformed into a multi-zero-pole system through Miller compensation, feed-forward compensation, and zero-pole tracking compensation techniques, enabling the LDO to achieve stability and reliability under different loads. The LDO proposed in this study was designed using a 110 nm CMOS process. The LDO can operate within a temperature range of −40–150 °C, with a low quiescent current of 57 μA. The power supply rejection ratio of the circuit is −22 dB at 1 MHz. When the load current jumps from 5 mA to 300 mA within 40 μs, the output voltage experiences an undershoot of 271 mV, an overshoot of 174 mV, and a maximum adjustment time of 100 μs. The load regulation is 0.00267 mV/mA, and the line regulation is 1 mV/V. [ABSTRACT FROM AUTHOR]

This paper presents a novel multibeam filtering antenna array based on a compact 3 × 3 Nolen matrix integrated with HRR filters for solar observations. The design facilitates the simultaneous recording of solar radio flux density and sky background flux density, streamlining calibration processes. The use of stub-loaded transmission line (SLTL) couplers achieves a significant 43.4% reduction in the size of the Nolen matrix, enhancing compactness. The hairpin ring resonator (HRR) filter with two transmission zeros (TZs) is employed to ensure electromagnetic compatibility (EMC). Given the limitations of conventional manual design methods, the intelligent grey wolf algorithm (GWA) is adopted to optimize the physical parameters of the Nolen matrix layout, realizing rapid and accurate achievement of the desired performance. The − 6. 2 ± 0. 15 dB transmission coefficient and 0°, −120°and + 120 °of output phase differences within 2° phase error are accomplished at 2.8 GHz. Finally, the proposed multibeam filtering antenna array is fabricated and measured to confirm its ability to generate the required three beams with filtering characteristics. The measured results have a good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

In this paper, a miniaturized dual-band frequency selective surface (FSS) for electromagnetic shielding applications is presented. The FSS unit cell provides band-stop response at the resonant frequencies of 0.95 GHz and 2.52 GHz. The FSS element is constructed by employing convoluted metal stripes that are positioned on both sides of the substrate. The proposed configuration enhances the electrical length of the resonator while maintaining its physical dimensions. Moreover, the unit cell of the FSS exhibits rotational symmetry, which enables polarization independent operation. The designed FSS structure demonstrates excellent miniaturization characteristics, with a cell size and thickness of 0.019 λ 0 × 0.019 λ 0 , and 0.00048 λ 0 , respectively. The cell size and thickness are calculated at the lower resonating frequency of 0.95 GHz. In addition, the stability of the proposed FSS structure is observed for both the TE and TM polarizations across an incident angle range of 0° to 80°. The resonating behavior of the structure is elucidated with the help of electric field and surface current distribution. Experimental verification of the dual-band FSS is conducted through the fabrication of a prototype on a FR4 substrate. The measured transmission coefficients are in good agreement with the simulated response for both TE and TM modes. Compared with the dual-band FSSs previously reported, the proposed FSS has the significant advantages of low profile and miniaturization. [ABSTRACT FROM AUTHOR]

Maximal ratio combining (MRC) and selection combining (SC) diversity techniques enhance wireless communication networks' reliability by mitigating fading effects and improving the signal-to-noise ratio (SNR) at the receiver. Hence, these techniques have a crucial impact on reducing the bit error rate (BER) and increasing the capacity of wireless communication systems. This paper introduces new exact mathematical formulas for the distribution of instantaneous SNR, BER and channel capacity per unit bandwidth (CpUB) for L-branch MRC and SC diversity receivers in offset quadrature amplitude modulation-based filter bank multi-carrier (OQAM/FBMC) systems for 5G wireless communication. Additionally, new formulations for BER and CpUB using the semi-analytical method have been derived. These formulas consider the combined effects of non-linear distortion from a high-power amplifier (NLD-HPA), the Rayleigh fading channel, and impulsive noise (IN). Monte-Carlo computer simulations verify the validity and accuracy of the derived theoretical instantaneous SNR, BER and CpUB across OQAM/FBMC-MRC and OQAM/FBMC-SC diversity system parameters, such as the number of branches (L), the input back-off (IBO) of NLD-HPA, and IN. According to the results of simulation modeling and a comparative analysis of performance, the OQAM/FBMC-MRC diversity system tends to have better BER performance and CpUB compared to the OQAM/FBMA-SC system in all scenarios. [ABSTRACT FROM AUTHOR]

The Intelligent reflecting surfaces (IRSs) have been established to show the capability to enhance spectral and energy efficiency by using the passive beamforming at the IRS point and joint optimization of the active beamforming at the base station (BS). However, in the smart wireless environments in which mostly passive RISs are deplored the estimation of the channel state estimation is challenging. This paper, therefore, aims to propose a channel estimation scheme with an improved performance in comparison with some other recently proposed estimation schemes. The proposed channel estimation scheme employs the hybrid strategy to combine the improved versions of traditional Orthogonal Matching Pursuit (OMP) and Subspace Pursuit (SP) compressive sensing algorithms as a basis for the proposed estimator. The proposed estimator, through computer simulations, shows improved performance when compared with the other four channel estimators that were recently documented in literature though with a slightly high computational complexity cost. [ABSTRACT FROM AUTHOR]

This paper examines a short-range Millimeter-wave antenna characterized by its compact design, coplanar waveguide feeding, and folded dipole shape, that operates across multiple frequency spectrums. The radiator is designed on a Rogers TMM4 material having the dimensions of 1.05 λ L × 1.05 λ L × 0.057 λ L (λ L : wavelength associated with the bottommost cut-off frequency). Adoption of a folded shape serves to augment the electrical dimension of the antenna by expanding the current-carrying path, thereby facilitating the attainment of the necessary frequency spectrums. The proposed antenna operates at 22.44–23.77 GHz (5.75 %), 26.68–30.35 GHz (12.87 %), 38.1–43.46 GHz (13.14 %), 49.13–54.48 GHz (10.33 %) and 57.63–67.85 GHz (16.29 %) spectrums with maximum gain and radiation efficiency of 8dBi and 94.5 % respectively. The work further delves into an in-depth analysis of antenna characteristics, encompassing aspects such as radiation pattern, surface current, group delay, and transfer function. All examined characteristics affirm that the proposed antenna exhibits versatility for diverse frequency bands, including but not limited to n257, n259, n260, n261, and various other 5G/beyond 5G wireless technologies. [ABSTRACT FROM AUTHOR]

This paper presents an automatic tuning method based on a stepping search algorithm for bandpass cavity filters. This method imitates human tuning manipulation without recourse to a theoretical model of filter. To a certain extent, this implementation can replace and optimize the tuning work rely on engineers' experience. The return loss and insert loss are the key indexes to measure whether the tuning terminated, and the hierarchical optimization objectives used as evaluation function of the method. To verify this approach, two screw- tuned cavity filters tuning instance are given with five screws and eleven screws respectively. [ABSTRACT FROM AUTHOR]

In this paper, a circularly polarized rectenna is proposed for microwave energy transmission, which is composed of a broadband Substrate Integrated Waveguide (SIW) antenna and a rectifier circuit. A dielectric resonator is loaded on the SIW antenna, enhancing the impedance bandwidth. Circular polarization is achieved by chamfering the diagonal of the rectangular patch. Two sections of microstrip branches are employed for good impedance matching over the broadband operation. Measured results show that the proposed rectenna has a good impedance performance (|S 11 | < −10 dB) and high RF-DC conversion efficiency (>50 %) over a relative bandwidth of 22.9 % (29–36.5 GHz). The maximum conversion efficiency of 67.5 % is realized at the input power of 18 dBm. [ABSTRACT FROM AUTHOR]

This paper presents a new proximity-coupling mechanism between a rectangular patch and a microstrip line with an open circuit terminal. The patch is located to cover both adjacent maximum-voltage (capacitive coupling) and maximum-current (inductive coupling) points of the standing wave on the feedline, and consequently, two orthogonal resonant modes with 90° phase difference are excited on the patch for generating a circularly polarized (CP) radiation. Based on this feeding mechanism, a dual-band dual-sense CP antenna is designed, which is composed of two linear rectangular patch arrays coupled to an open-ending microstrip line. It is realized on a single-layer substrate and its CP rotating sense in each band is opposite to each other. For verification, the antenna operating at 5.0 and 8.0 GHz are designed, fabricated, and tested. Noting that the design concept can be easily implemented to other frequency bands. The measurements result in an impedance-matching bandwidth of 4.72 – 5.10 GHz and 7.50 – 8.20 GHz. The antenna is left-hand CP for the lower band and right-hand CP for the upper band. In addition, the prototype shows a 3-dB axial ratio bandwidth of 4.93 – 5.02 GHz and 7.40 – 8.10 GHz and peak gains of 11.4 and 12.7 dBic at the lower and upper bands, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a reconfigurable bandstop frequency selective surface (R-FSS) design capable of switching across C, X and Ku-bands. The electronic switching mechanism is achieved in real-time through PIN diodes. The combination of rectangular loops is selected as unit-cell and PIN diodes are strategically placed to dynamically adjust the bandstop region. The device operates in three distinct modes corresponding to the activation status of the PIN-diodes. For TE polarization, Mode 1 encompasses the Ku-bandstop (12.64–14.75 GHz), Mode 2 corresponds to the C/X-bandstop (6.62–11.28 GHz), and Mode 3 involves the X-bandstop (9.82–11.63 GHz), whereas X-bandstop characteristic is observed for TM polarization (9.054–––11.29 GHz). In TE polarization, each configuration is defined by specific equivalent circuit models, featuring an inductance in parallel with series L-C resonant circuit, an L-C resonant circuit in parallel with the inductance, and two L-C resonant circuits in parallel, respectively. Additionally, for TM polarization, the configuration incorporates two parallel L-C resonant circuits. A prototype of the proposed R-FSS is fabricated and measured. The results demonstrated effective switching operation across the C, X and Ku-band stopbands, depending on the biasing of the PIN diodes. The experimental outcomes are consistent with the simulation results, affirming the compatibility and functionality of the proposed R-FSS design. [ABSTRACT FROM AUTHOR]

This paper presents a W-band stable high gain 2 × 2 cavity-backed slot antenna array fed by compact high-order mode substrate-integrated cavity (SIC) with substrate-integrated waveguide (SIW) technology. The antenna element incorporates a 2 × 2 subarray of cross-shaped slots, excited by a high-order mode (TE 220) SIC, ensuring uniform amplitude and balanced phase to achieve stable high-gain and high efficiency. Moreover, an additional SIW cavity is stacked above the 2 × 2 cross-shaped slots, incorporating a rectangular slot etched on the surface of the SIW cavity for radiation to further enhance the gain. This novel architecture yields a gain enhancement of 2.6 dBi compared to the traditional unstacked SIW cavity antenna. A prototype antenna array, consisting of 2 × 2 radiation elements and a low-loss 1-to-4 SIW power divider integrated with waveguide (WG) to SIW transition, is designed and fabricated in standard PCB technology. The measured results exhibit a −10 dB impedance bandwidth range from 91 to 97 GHz, a peak gain of 18.5 dBi, and a peak aperture efficiency of up to 78 %. [ABSTRACT FROM AUTHOR]

This paper presents a wideband and high-fundamental rejection self-mixing frequency tripler in a 40-nm CMOS. The proposed tripler consists of an input half-shielded transformer balun, an even-harmonics generator, a single-balanced mixer, a slow-wave coupling-line filter and an output half-shielded Marchand balun. The half-shielded coupling structure improves the coupling coefficient of the coupling-line components and also features high design freedom. Consequently, the half-shielded transformer balun achieves a broadband performance. The half-shielded Marchand balun achieves a 1-dB bandwidth of 109 GHz (49.7 %) and a minimum insertion loss of 1 dB. The slow-wave coupling-line filter enhances the fundamental rejection of the proposed tripler with low insertion loss of 1.5 dB, wide 1-dB bandwidth of 162 GHz (62.8 %) and compact footprint (0.01 mm2, 0.00535 λ2). The slow-wave coupling-line filter achieves a broadband low-frequency rejection over 18.6 dB from 65 to 88 GHz. Due to the above-mentioned technology, the tripler achieves a 3-dB bandwidth of 49 GHz from 195 to 244 GHz and a fundamental rejection larger than 23 dBc. Compared with the state-of-the-arts, the proposed self-mixing tripler features wide bandwidth, high fundamental rejection and compact core area among silicon-based triplers. [ABSTRACT FROM AUTHOR]

The energy of Wireless Sensor Network (WSN) in edge network is limited. In order to save energy, data bundling is proposed to reduce the energy consumed in setting up connection links by joining several packets into a single unit. However, although current data bundling schemes can reduce energy consumption, they will increase the delay of data routing, so it makes the multi-hop end to end delay a lot in WSN. Also, there is no appropriate solution to tackle the delayed growing problem caused by data bundling. And the energy consumption of the Acknowledgment (ACK) transmission is not comprehensively considered either. Regarding to those issues of previous researches, in this paper, a Data and ACK Bundling Scheme (DAB) is proposed to aggregate several data or ACK packets into a single unit to reduce the energy consumption as well as the end to end delay of the WSN. In the proposed DAB scheme, not only multiple packets but also ACK bundling into a single unit can reduce energy consumption. More importantly, the parameters of bundling technology are optimized from a global perspective in DAB scheme, so that WSN can not only improve the network lifetime, but also reduce the end to end delay which is impossible in previous studies. The theoretical analysis and experimental results illustrate that, while ensuring the reliability of data collection, our DAB scheme improves the energy efficiency by 29.03 % and reduces the delay by 22.29 % when compared with our traditional data collection scheme. [ABSTRACT FROM AUTHOR]

This paper introduces a compact dielectrically loaded antenna with an isoflux beam. Fabricated from a lattice of alternating dielectric and air layers, this antenna is excited via a waveguide feed. By varying the thickness ratio of the dielectric layer to the overall unit cell, the effective permittivity of the antenna can be dynamically adjusted. Experimental results reveal that the antenna achieves an isoflux beam pattern in the E plane while projecting a pencil beam in the H plane. The maximum gain, about 12.2 dBi, manifests at a 30-degree offset from the boresight within the 22 GHz to 35 GHz frequency range. The height of the dielectric component measures roughly twice the wavelength at the central operational frequency. Design methodology has been validated through both fabrication and measurement, confirming performance of this proposed antenna, which boasts a simple structure and cost-effective production. [ABSTRACT FROM AUTHOR]

This paper theoretically analyzes the network phase solution space under Doherty, Outphasing, and hybrid modes. A dual-input wideband Doherty-Outphasing power amplifier (DOPA) design method is proposed. This method can ensure that the output back-off (OBO) amount is further increased based on the OBO amount of Doherty power amplifier. To prove the reliability of the proposed method, a hybrid DOPA power amplifier in the band of 1.7–2.4 GHz with an OBO amount of 12 dB is designed. The experimental results also show that the output power of the hybrid DOPA is 48.6–49.5 dBm in the band of 1.7–2.3 GHz, and the saturation efficiency is 57%–63%. The efficiency at 12 dB, 9 dB and 6 dB OBO is 42%–50%, 46%–59% and 50%–63% respectively. The digital pre-distortion correction is carried out at 1.8, 2.1 and 2.3 GHz frequency points, and the adjacent channel power ratio is lower than -47.7 dBc. Simulation and experiment results can verify the effectiveness and correctness of the proposed method. To the best of our knowledge, it is the first time to achieve such a wide bandwidth to the hybrid DOPA with the proposed design method. [ABSTRACT FROM AUTHOR]

To reduce the complexity of direction-of-arrival (DOA) algorithms in polarization-sensitive arrays and maintain high estimation accuracy while decreasing runtime, this paper proposes a channel compression model based on orthogonal dipole arrays. In addition, a DOA estimation algorithm using atomic norm minimization (ANM) is introduced for this model. This algorithm performs eigenvalue decomposition on the covariance matrix of the data received from the polarization-sensitive channel compressed array. A new observation vector is constructed for the ANM problem under the channel compression model using the obtained eigenvalues and eigenvectors. Subsequently, a Toeplitz matrix is constructed from the optimal solution of the semi-positive definite programming (SDP) problem. The Vandermonde decomposition of the Toeplitz matrix provides estimates of the signal DOA parameters. By combining the vectorization result of the covariance matrix and the least-squares calculation, the polarization auxiliary angle and polarization phase angle information of the incident source are also obtained. Simulation experiments compare the root-mean-squared error (RMSE) of each algorithm at different angular intervals and signal-to-noise ratios (SNR) to confirm the validity of estimating DOA and polarization parameters. [ABSTRACT FROM AUTHOR]

In this paper, a dual-band bandpass filter (D-BPF) and a diplexer are proposed. Their core structures are both a lumped element single-band bandpass filter (S-BPF) with dual transmission poles (TPs) and dual transmission zeros (TZs). For the D-BPF, based on this S-BPF, single-band impedance matching networks (S-IMNs) are used to form the second/third passbands. Two S-BPFs with different first reactance elements are used for the diplexer to achieve good isolation without T-junction. Finally, the D-BPF and the diplexer with center frequencies of 2.26/4.75 GHz and 2.3/5.75 GHz are fabricated by thin-film integrated passive device (IPD) technology. The physical size of the D-BPF chip is only 1.5 × 1.1 mm2, and the diplexer chip is 2.3 × 1.5 mm2. Measured results show they both have the advantages of good insertion loss, excellent impedance matching, high roll-off, and broad stopband rejection. The isolation of the diplexer is greater than 23 dB from 0 to 10 GHz. [ABSTRACT FROM AUTHOR]

This paper proposes a method for introducing transmission zeros (TZs) in filters using dual-mode resonators. By loading a dual-mode resonator as a second-order extracted-pole unit (EPU) at the input or output of the filter, a pair of finite TZs can be introduced without cross-coupling. This approach reduces the size of the filter while generating two finite transmission zeros compared to conventional methods. Since the dual-mode resonator is characterized by its separable odd and even modes, and by adjusting the resonant frequency of the EPU, it can achieve an arbitrary distribution of TZs. It is worth noting that the EPU does not affect the insertion loss of the filter because it operates mainly outside the passband. Furthermore, this work delves into the EPU's mechanism for generating TZs and the method of adjusting TZ position by designing filters of second, fourth, sixth, and eighth orders, providing a solid foundation for the creation of higher-order filter circuits. [ABSTRACT FROM AUTHOR]

A simple decoupling technique by using conformal metal strips is investigated for isolation enhancement of terahertz (THz) multi-input–multi-output (MIMO) dielectric resonator (DR) antennas (DRAs) in this paper. Metal strips with proper dimensions are symmetrically printed on both sides of the upper surface of DRs. The introduction of metal strips can cause disturbance to the electromagnetic (EM) fields inside the DRs by introducing the induced fields, thereby suppressing the diffusion of EM fields and rearranging the EM fields, ultimately reducing the level of coupling and enhancing the isolation between ports. Two kinds of MIMO antennas, i.e., using two DRs and sharing one DR, are used as implementation examples to verify the effectiveness of the proposed technique. Corresponding results show that by optimizing the dimensions of the metal strips reasonably, the isolation for antenna containing two DRs increased from 14.7 to 59.2 dB at 2.98 THz, while the isolation for another sharing one DR increased from 7.1 to 40 dB at 3.64 THz. Excellent improvement of isolation has been achieved through the proposed technique and the proposed MIMO antennas are expected to be applied in future THz communication. [ABSTRACT FROM AUTHOR]

By utilizing transversal signal interference concepts, a tri-band bandpass filter with a triple transmission path is proposed in this paper. Triple transversal transmission paths are respectively constructed with the employ of parallel coupled stub loaded resonator, microstrip gap coupled line and parallel coupled shorted stub loaded resonator. Based on the triple transversal transmission path, nine transmission poles (TPs) are excited; therefore, triple independently controllable wideband passbands are realized. Due to the transversal cancellation between transmission paths with the virtual short mechanism of each transmission path, seven transmission zeros (TZs) can be excited and managed. Therefore tri-wideband characteristics with high selectivity and high band-to-band isolation can be obtained by properly adjusting the TPs and TZs. To further demonstrate the proposed design methodology, a prototype tri-wideband bandpass filter operating at 1.93/3.52/5.11 GHz with fractional bandwidth of 11.8 %, 19.8 % and 22.8 % for LTE, WiMAX, Wi-Fi and 5G applications is synthesised. The presented tri-wideband bandpass filter is designed, manufactured and measured. The measured results agree well with theoretical predictions, which exhibit superior performance such as sharp shirts, high band-to-band isolation compact size and ideal out-of-band suppression. [ABSTRACT FROM AUTHOR]

The semiconductor industry has long benefited from CMOS transistors in realizing advanced VLSI circuits. However, achieving area-energy optimization in CMOS-based VLSI circuits has become increasingly challenging due to short-channel effects. Another obstacle in manufacturing these transistors is the adoption of body-biasing techniques to adjust the threshold voltage (V th) for developing ternary logic-based circuits. Researchers are now exploring emerging devices like graphene nanoribbon field-effect transistors (GNRFET) as potential candidates for future electronics. GNRFET devices not only leverage graphene's remarkable properties but also benefit from the ability to achieve distinct V th through tuning the width of graphene nanoribbons. This paper focuses on using tri-state 32-nm GNRFET devices to implement a novel area-energy optimized ternary multiplier circuit. To attain a logic '1′ in the proposed circuit, a power-efficient voltage division technique is employed. Additionally, efficient design approaches are used to reduce the critical path length and decrease the number of necessary transistors. Simulation results using HSPICE demonstrate that the proposed design reduces energy consumption by a minimum of 6.75% and up to 37.50% compared to other state-of-the-art 32-nm GNRFET-based TMUL circuits. Furthermore, the proposed design decreases both the area and complexity by utilizing a single-V DD and incorporating 24 transistors. [ABSTRACT FROM AUTHOR]

Co-site full-duplex communication system is facing self-interference (SI) issues caused by tremendous gap between Tx power and Rx sensitivity. SI suppression in the propagation domain is addressed by a co-polarized diplexer antenna with high port isolation in this paper. It shares a dual-band microstrip antenna with a small frequency ratio, at 1.5 and 2.0 GHz as an example. A shorting pin directly connects the antenna and diplexer, avoiding 50-Ω interface and impedance matching circuit. The diplexer is composed of open-loop resonators (OLRs) and step-impedance resonators (SIRs). Compact channel filters are constituted by OLRs, and SIRs are adopted to improve the filtering response of the diplexer. General guidelines of the diplexer are given through rigorous analysis. The fractional bandwidths of the lower and higher channels of the diplexer are 4% and 3%, and the fractional bandwidths of the diplexer antenna are 1.5% and 1%, respectively. The port isolation is greater than 53 dB for both channels. Size of the diplexer antenna is 0.65 λ ×0.60 λ ×0.016 λ , where λ is the free-space wavelength at the lowest operation frequency. Potential advantages of the proposed antenna in suppressing SI are validated using Software-Defined Radio, which is potentially useful in full-duplex communications. [ABSTRACT FROM AUTHOR]

This article proposes two new wideband common-mode noise suppression filters based on a defected ground structure. The first design uses the Butterworth equivalent circuit achieving a fractional bandwidth of 117 %. At first, the resonators are arranged next to each other and the equivalent circuit is extracted. Also, samples with different dimensions of resonators are prepared by electromagnetic simulation analysis, and the fuzzy interpolation method is used for estimating the circuit behavior. The ADS software is used to optimize the values of the variables to achieve the desired bandwidth in the schematic environment. This paper utilizes the Taguchi method to strike a balance between various parameters in the filter design, aiming to minimize errors during the fabrication process. Then, the new values estimated with the fuzzy interpolation method are verified by electromagnetic simulation. The fractional bandwidth of the filter increases to 124 %, and noise can be suppressed by more than 10 dB at the center frequency of 21.45 GHz in the range from 8.1 to 34.8 GHz, with a loss of less than 3 dB in the differential lines. A new equivalent circuit is proposed using the first-order Chebyshev model. It is observed that the electromagnetic simulations and circuit modeling have good agreement with the measurements. Moreover, the eye pattern with a speed rate of 21.45 Gb/s is proposed for USB 3.2 and HDMI 2.0 applications. [ABSTRACT FROM AUTHOR]

A 0.5–15 GHz ultra-wideband (UWB) RF reconfigurable receiver in UMC 28 nm CMOS used for IR-UWB (impulse radio UWB) radar system is proposed in this paper. This receiver employs a 0.5–8 GHz path and an 8–15 GHz path to achieve the wide frequency band, and we proposed an RF channel select voltage-to-time converter (VTC) circuit. Two different low noise amplifiers (LNAs) are adopted in the two paths to obtain the high performance of noise figure (NF) and gain. The common drain stage and resistance negative feedback technology as well as the source degeneration inductive technology are introduced to achieve a high flat gain and fine input matching. The R-2R variable load network of a programable gain amplifier (PGA) gives it a nearly 24 dB dynamic range and approximately linear gain control. A 500MS/s time domain analog to digital converter (TD-ADC) with an equivalent sampling rate of 16GS/s is shared for the two paths which can realize the direct RF sampling. The input RF signal path selection is implemented by configuring the Band_sel signal. The receiver has reconfigurability of the RF front end and better power consumption and area. In the frequency of 0.5–8 GHz, the S11 is below −7.9 dB and the NF is smaller than 6 dB. In the frequency of 8–15 GHz, the S11 is below −8dB and the NF is smaller than 11 dB. The receiver dissipates 242.72mW with an area of 1.01 mm2 [ABSTRACT FROM AUTHOR]

This paper introduces a fusion design method of a six-port waveguide (WG) coupler integrating tight and loose coupling together. The couplers exhibit a compact size due to the stacked configuration of three WGs. A methodology for designing the integrating tight and loose coupler is presented. The tight and loose coupling is achieved by setting a rectangular slot in the common narrow wall along with one or two cross slots in the common broad wall. Inspired by the superposition of TE 10 and TE 20 modes used to design the short-slot −3-dB coupler. The loose-coupling part of the fusion design is analyzed theoretically utilizing modes superposition. Based on the theoretical analysis, the loose coupling can be precisely designed, meanwhile, low coupling-level fluctuation can be obtained in the operating band. For demonstration, two design examples are designed and a prototype centered at about 3.73 GHz is fabricated. The fractional bandwidth (FBW) (| S 11 | < −15 dB) is about 28.4 %. Within it, the tight coupling (−3 dB) coupler achieves ± 0.5 dB amplitude imbalance. Meanwhile, the loose coupling (−20 dB) coupler achieves little fluctuation of < 0.56 dB and its isolation is better than 25 dB. [ABSTRACT FROM AUTHOR]

This paper presents a novel planar filtering antenna (filtenna) with simple layout based on tightly-coupled different-length monopoles. Its design methodology is based on an even-mode/odd-mode decomposition of the monopole currents, and the combination of both modes in a multimodal circuit model that facilitates the design and tuning of the antenna and the accompanying feeding network, since most of the process is performed using fast circuit simulations. The circuit model casts light into the interaction between conducting and radiating modes in the bulk of the antenna, and on how this interaction can be used to propose feedback loops that increase and define the radiation band. Using these modal tools, a filtenna was designed and fabricated to fully cover the new 5G frequency bands (n77, n78 and n79) from 3 to 5 GHz that are currently being adopted by many countries for high-capacity data transmission. It features a 62.9% FWB, dipole-like radiation patterns, good out-of-band rejection up to 10 GHz, and a very good trade-off between design/structural-simplicity and bandwidth. [ABSTRACT FROM AUTHOR]

Approximate circuits are extensively considered in error-resilient applications to reduce the design complexity. A multiplier is known as a key arithmetic unit of computational block, and thus improving the performance of the multiplier is significantly important to achieve an effective processor. In this paper, we develop two new inaccurate multipliers using approximate 4:2 compressor. Applying error correction block in the structure of these 8-bit multipliers remarkably increases the accuracy of design. The design performance and error metrics of the multipliers are analyzed. Furthermore, as an image processing application, we consider several benchmark images, and compare the quality metrics of image multiplication of our proposed multipliers to those obtained from different under-test multipliers of the previous studies. The design of multipliers is performed using HSPICE with 14 nm FinFET technology. The results demonstrate that the proposed multipliers provide suitable efficiency in the error analysis when compared to the exact multiplier in image processing application. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel approach for designing single-/multiple-band bandpass filters (BPFs) using a hybrid metamaterials approach, incorporating substrate integrated waveguide (SIW), spoof surface plasmon polariton (SSPP), and defected surface structures (DSSs) technologies. The substrate-integrated plasmonic waveguide (SIPW) is constructed by embedding a hybrid dual SSPP into a three-layer SIW. The SIPW demonstrates a reduced phase velocity and a lowered lower cutoff frequency, extracted from the slow-wave dispersion relationship. Initially, the SIPW-based single-band metamaterial BPF demonstrates miniaturized size and broadened bandwidth. Furthermore, by loading a pair of complementary electric-inductive capacitive (ELC) resonators consisting of DSSs and adjusting their symmetry properties and geometric parameters, multiple BPFs from 1 to 3 are realized. To validate the proposed designs, three prototypes are fabricated and measured. The results demonstrate good filtering performances of proposed metamaterial BPFs, featuring high reflection loss (S 11 < −10.5 dB) and a high level of out-of-band rejection exceeding 25 dB between multiple passbands. [ABSTRACT FROM AUTHOR]

In this paper, a compound reconfigurable electronically switched parasitic monopole antenna is reported for sub-6 GHz (n77/n78 bands) wireless standards and vehicular communication. The antenna comprises a half-hexagonal-shaped radiating element and two inverted L-shaped parasitic stubs. These stubs are connected through two PIN diodes, allowing for control over frequency. An additional pair of PIN diodes incorporates analogous parasitic stubs into the ground plane to facilitate pattern tilting and polarization. By switching these PIN diodes across seven operating states (OS), the antenna structure could resonate in a single band, spanning 4.5–5.8 GHz (sub-6 GHz higher band), with an omnidirectional pattern specific to OS1. In OS2 and OS3, the antenna resonates in a single band within the range of 4.1–5.7 GHz, featuring beam tilting with linear polarization. In OS4 and OS5, the structure has two bands: one covers 3.3–4.2 GHz (5G-n77 band) with linear polarization, and the other covers 5.1–6.1 GHz (5G WLAN band) with right-hand circular polarization (RHCP) in OS5 and left-hand circular polarization (LHCP) in OS4 with an axial ratio bandwidth of 14.5 %, including pattern tilting within the range of ± 340. Finally, in the OS6 and OS7 structure introduce dual bands of 3.3–3.8 GHz (5G–n78 band) and 4.8–5.8 GHz (sub-6 GHz higher band). Both bands feature LHCP/RHCP with an axial ratio bandwidth of 8.57 % for the lower resonant band and 7.4 % for the higher resonant band. Additionally, it incorporates radiation pattern reconfiguration capabilities. The structure is printed on an FR-4 substrate and measures various associated parameters. The experimental results closely match the simulated results. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to design broadband Doherty power amplifiers (DPAs) with extended fractional bandwidth (FBW). A parameterized load modulation network (LMN) and complex combining loads are proposed that can extend the FBW while providing more accurate back-off impedance. To examine the influence of parameter variations in the LMN on the broadband performance of the DPA, we utilize the parameter scanning method and subsequently select the optimal parameters in the LMN. Additionally, three-dimensional computer visualization techniques is invoked to visually examine the impedance solution space of the complex combining loads. A DPA prototype with a bandwidth of 0.85–1.8 GHz is then designed and implemented using commercial GaN transistors to validate the proposed architecture. The fabricated DPA attains a measured gain of 14.2–15.7 dB and a saturated power of 43.0–44.9 dBm. Across the designed operation band, the measured drain efficiency reached 51.6%–73.6% at saturation and 43.7%–56.7% at 6 dB output power back-off. When driven by a 20 MHz modulated signal with a peak-to-average power ratio (PAPR) of 8 dB, the average efficiency of the fabricated DPA is higher than 46.7%. [ABSTRACT FROM AUTHOR]

This paper presents designs of ternary and quaternary up/down counters of single and multiple digits using CNTFET. The proposed counters have a special feature of counting in dual mode; up counting and down counting which makes these designs distinct from other existing designs. The proposed counters are designed using ternary/quaternary D flip-flops and a dynamic successor-predecessor circuit. The D flip-flops are built using standard ternary/quaternary inverters (STI/SQI) with an additional reset feature. The proposed dynamic successor-predecessor circuit has the capability of acting either as a successor or as a predecessor circuit based on a control signal. Counter circuits of multiple digits have been achieved with the help of a few additional transistors along with the single-digit counter circuits. All the proposed designs have been simulated in HSPICE using Stanford University's 32 nm CNTFET model and simulation results have been noted. When compared with existing designs, the proposed designs show improvements in power and energy efficiency. [ABSTRACT FROM AUTHOR]

In this paper, an active frequency-selective rasorber (AFSR) with a wide tunable range of passband windows is proposed. The proposed AFSR includes an absorption layer, a frequency selective layer, and an air spacer between them. The absorption layer is embedded with resistors to aid in the absorption of out-of-band unprofitable signals, and the frequency selective layer is designed to provide tunable transmission passbands through in-band beneficial signals. A design method for the AFSR embedded with varactors based on equivalent circuit model is proposed. Driven by an applied voltage, the transmission passband of the proposed AFSR can be shifted from 3.4 to 6.9 GHz. The absorption bandwidth covers from 6.4 to 14.1 GHz. In addition, the proposed AFSR exhibits stable performances up to 45° angle of incidence wave. The measurement results of the fabricated prototype are in good agreement with the simulation results. This work provides a feasible solution for flexible simultaneous regulation of radiation and scattering. [ABSTRACT FROM AUTHOR]

In this paper, a Substrate Integrated Waveguide (SIW) based self-triplexing antenna-sensor is introduced. The proposed structure can act as a sensor for concurrent detection of three chemical materials. Further, it can be used as a self-triplexing antenna for simultaneous operation at three different frequencies. To that end, initially, a half mode circular SIW cavity is designed. Then, it is divided into three parts. In each part, the position of maximum electric field is determined and subsequently, three holes are located in the positions for material insertion. Finally, considering the vacuum as the inserted material for each hole, each cavity is adjusted to operate at its operation frequency (4.8, 5.8, and 6.6 GHz). Altering the permittivity of the objects inserted in the holes, the resonant frequencies are changed and consequently the type of material is determined. The simulated and measured results validated the performance of proposed antenna-sensor as well. In all the frequency bands, the reflection coefficients as well as mutual coupling among ports are below −20 dB. It should also be expressed that such an SIW structure with the capability of sensing and propagation is provided for the first time. [ABSTRACT FROM AUTHOR]

This paper presents a low-power 18/12-bit 1 MS/s reconfigurable pipelined-successive approximation register analog-to-digital converter (pipelined-SAR ADC). The proposed pipelined-SAR ADC employs a two-stage SAR structure coupled through a residual amplifier, with the forestage performing 12-bit coarse quantization and the poststage handling 7-bit fine quantization, one bit of redundancy is contained in the rear stage. The input signal is sampled by the first stage, SAR ADC, using the upper plate of a capacitor array and is quantized by charge redistribution. This eliminates the need of additional DACs and subtractors, allowing direct acquisition of the residuals. In addition, the residuals can be amplified by reusing the capacitor array as a switching capacitor. To minimize static power consumption, dynamic logic is adopted in each module of the pipelined-SAR ADC. The calibration of comparator offset and capacitor mismatch is carried out using analog front-end calibration techniques. Implemented in a 180 nm CMOS process, the simulation results show an extra-low power consumption of 1.76 mW with 3.3 V supply voltage and 1 MS/s sampling rate, indicating an exceptional Schreier figure of merit (FOMs) at 181.64 dB. By shutting down the modules of the second-stage SAR ADC, the 18-bit ADC can be dynamically configured as a 12-bit ADC with a sampling rate of up to 5 MS/s. [Display omitted] • The proposed pipelined-SAR ADC eliminates the need for additional DACs and subtractors. • The proposed ADC can be reconfigured from 18-bit to 12-bit. • Capacitance in residual amplifier reuses capacitance of the first stage SAR ADC. [ABSTRACT FROM AUTHOR]