Mid Band Research Articles

Impact of interface trap charge and temperature on the performance of epitaxial layer tunnel field effect transistor

A simulation study of the impact of interface traps on the performance of the Epitaxial Layer Tunnel Field Effect Transistor (ETLTFET) having Si(1-x)Gex as source material is investigated in terms of interface Trap distribution, energies, random trap fluctuation (RTF), and temperature in comparison with FinFET. The study revealed a similar trend of Vth shift for ETLTFET and FinFET for a given trap type. For both ETLTFET and FinFET, the donor interface trap with energy above the semiconductor mid band gap can cause a shift in ION as well as IOFF, while the acceptor interface trap has a comparatively wider energy range. Again, trap induced SS degradation is minor in ETLTFET than its counterparts. In the case of RTF in nano-scaled devices, the fluctuations in ION and Vth induced by interface traps are found to vary with the position of the trap, and the variations at ETLTFET are relatively more minor than the FinFET. Furthermore, the presence of interface trap charges alters the device's temperature sensitivity which could be detrimental for the device to be utilized in sensor applications.

Gain and Bandwidth Enhanced Optimized Notch Loaded Microstrip Antenna for 5G Applications

In this paper, a rectangular patch antenna is presented loaded with T-shaped notch as well as having truncated corner for the enhancement of gain and bandwidth which is bring into play for mid band of 5G applications. With design frequency of 3 GHz, this prototyped design antenna having 50 Ω microstrip line feed for impedance matching and simulation has been performed using IE3D Mentor Graphics simulation software. Fractional impedance 51.3% has been observed from 2.39 to 4.04 GHz. An enhanced peak gain of 5.05 dBi and maximum directivity of 6.214 dBi has been observed at 4.22 GHz and 4.34 GHz respectively.

Dual-Band CMOS RF Front-End Employing an Electrical-Balance Duplexer and N-Path LNA for IBFD and FDD Radios

This article proposes a dual-band complementary metal-oxide-semiconductor (CMOS) radio frequency (RF) front end employing a hybrid transformer-based electrical-balance duplexer (EBD) and N-path filter embedded low-noise amplifier (LNA) for both in-band full duplexing (IBFD) and frequency-division duplexing (FDD) radios. To securely obtain sufficient self-interference cancellation (SIC) or transmitter (TX) leakage rejection in IBFD and FDD modes of the EBD at both low-band (LB) (0.7-1 GHz) and mid-band (MB) (1.8-2.2 GHz) frequency ranges, a band-switchable hybrid transformer is designed with a finely adjustable balance network to control the antenna impedance variations. In addition, the four-phase N-path LNA is utilized to further offer TX leakage rejection in the FDD operation. This RF front-end is fabricated using a 65-nm CMOS technology and is mainly characterized by long-term evolution frequency bands. The demonstrated design achieves SIC and TX leakage rejection greater than 55 dB for IBFD and FDD modes of all measured frequency bands, which has a maximum power handling capability of +25 dBm. Furthermore, the design attains voltage gains greater than 8.7 dB for LB and 3.7 dB for MB, noise figures of 10.4 dB for LB and 12.1 dB for MB, out-of-band (OB) P1dBs greater than +21.4 dBm for LB and +21.5 dBm for MB, and OB IIP3s greater than +39.7 dBm for LB and +43.1 dBm for MB. It draws a bias current of 23.8 mA from the LNA and output buffer with a nominal supply of 1.2 V and has an active area of approximately 2 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Design and Analysis of Co-planar Waveguide Fed Circular Monopole Antenna for Ultra Wideband Application

A Printed monopole antenna with coplanar waveguide (CPW)- fed having circular shape patch to met the Ultra Wideband technology whose bandwidth is greater than 500MHz is proposed in this article. To enhance the bandwidth co-planar ground plane plays a great role for a frequency band which belong to mid band for 5G frequency spectrum. A good radiation pattern which is usually in 8shape can be achieved with this proposed antenna.

Clustering of excess oxygen in uranium dioxide: A first-principles study

To explore the behavior of excess oxygen in uranium dioxide (UO 2+x ), we have investigated the energetics of oxygen interstitial clusters using density function theory (DFT+U). The calculations are based on transverse 3k antiferromagnetic UO 2+x with a P a 3 ¯ configuration. The spin-orbit coupling increases the possibility of capturing the ground state of UO 2 without special control. The size of the simulation boxes significantly impacts the formation energies and thus the clustering energies of defects, especially for large oxygen interstitial clusters with charge states. The interactions between two negatively charged oxygen interstitials as a function of distance in UO 2+x demonstrate that the oxygen interstitials prefer a split di-interstitial configuration for distances less than 0.5 nm, but the mono-interstitial is the preferred configuration for distances greater than 0.6 nm. Cube-octahedral clusters are metastable and may relax to split-type clusters. The clustering energies of oxygen interstitial clusters imply that the interstitials are more prone to cluster for Fermi levels close to the valence band, while the clustering becomes energetically unfavorable at Fermi levels beyond the mid band gap. The Bader charge analysis indicates that neighboring uranium ions to the oxygen interstitials can oxidize to a +5 valence state.

A Reconfigurable Wearable Antenna for Mid Band 5G Applications

Soon, everything should be connected by 5G wireless, including wearable devices that are booming fast recently. Wearable antennas are becoming increasingly common in consumer electronics. To achieve 5G, wearable devices should support much wide band width and high rate of data with better consistency. In this paper a reconfigurable wearable antenna is implemented on a fabric substrate. The proposed antenna may fit for reconfiguration of the frequency to work on MID band (3 – 5.5GHz) of 5G. The proposed antenna can be a part of military uniform or any other garment and can be employed in Wi-Fi, WLAN, Satellite,5G mobile and cognitive radio communication. The shape of the antenna has been accomplished by placing each feature of reconfiguration mentioned above in the same antenna and performing the parametric analysis to obtain an optimal prototype that could allow the achievement of good results with fabric such as polyester as substrate.

Synthesis of CaSnN2 via a High-Pressure Metathesis Reaction and the Properties of II-Sn-N2 (II = Ca, Mg, Zn) Semiconductors.

A novel ternary nitride semiconductor, CaSnN2, with a layered rock-salt-type structure (R3̅m) was synthesized via a high-pressure metathesis reaction. The properties and structures of II-Sn-N2 (II = Ca, Mg, Zn) semiconductors were also systematically studied, and the differences among them were revealed by comparison. These semiconductor materials showed a rock-salt- or wurtzite-type structure depending on the combined effect of the synthetic conditions and the characteristics of the group II elements. Additionally, the rock-salt-type structures of CaSnN2 and MgSnN2 (i.e., the ambient-pressure phase) were different from those predicted using first-principles calculations. Further, on the basis of first-principles calculations and consideration of the pressure effect, the recovered CaSnN2 sample showed an R3̅m structure. CaSnN2 and MgSnN2 showed a band gap of 2.3-2.4 eV, which is suitable for overcoming the green-light-gap problem. These semiconductors also showed a strong cathode luminescence peak at room temperature, and generalized gradient approximation (GGA) calculations revealed that CaSnN2 has a direct band gap. These inexpensive and nontoxic semiconductors (II-Sn-N2 semiconductors (II = Ca, Mg, Zn)), with mid band gaps are required as pigments to replace cadmium-based materials. They can also be used in emitting devices and as photovoltaic absorbers, replacing InxGa1-xN semiconductors.

Desynchronization Attacks Resilient Watermarking Method Based on Frequency Singular Value Coefficient Modification

Desynchronization is a very challenging type of attack in audio watermarking. The traditional singular value decomposition (SVD) based audio watermarking methods embed the watermark information by modifying the singular value of individual segment, which have little resistance against desynchronization attacks. In this paper, we propose a novel frequency singular value coefficient (FSVC) feature, which reflects the ratio between the singular values of two consecutive segments and is insensitive to desynchronization attacks, to carry the watermark bits. To our best knowledge, it is the first time that the ratio between singular values is employed for audio watermarking. In the proposed method, the discrete cosine transform (DCT) is performed on two consecutive segments of the host audio signal and SVD is applied to the DCT coefficients of the mid frequency band of each segment to extract the FSVC. Then the watermark bits are embedded by adjusting the values of the FSVC. The watermark embedding procedure is optimized to minimize the perceptual quality degradation and an error buffer is created to enhance the robustness. As a result, the proposed method can achieve a much higher embedding capacity than the existing methods tackling desynchronization attacks. The impact of desynchronization and common signal processing attacks on the proposed watermarking method is mathematically modeled, and the effectiveness of the proposed method against these attacks is theoretically and experimentally validated.

Performance of defected ground structure with miniaturized microstrip patch antenna using RMPA substrate material

Abstract A parallel structural antenna with the acts slot configuration is indicated for process of 5G wireless technology. The direct slot configuration defined within the patch antenna drives the 5G mid band and twin band frequency reaction in the frequency location without the conditions. Next, a 2-D Double Periodic Electronic Band (EBG) shape is carried out below the metal ground aircraft to request an extended impedance bandwidth for RMPA Materials. The slot duration and feature changed into designed for an impedance bandwidth of 12.49% and 4.49% at three pass band frequencies of 532 GHz and, 835 GHz respectively. Simulated with measured gain and reflection coefficient of correct settlement for bending bandwidths. The antenna array length is 33.5 mm × 33.5 mm. The antenna modified structure and the experimental effects were compared with all the other existing systems. The proposed antenna, which makes use of the EBG structure, suggests pics and excessive sensitivity steady with a massive impedance bandwidth, meeting the necessities of the IoT software program supplied with the resource of 5G technology.

Study of a neutron-resistant p+-Si/n-ZnO photodetector with avalanching gain

The photo detection properties under large reverse bias voltage and neutron irradiation effects of the p+-Si/n-ZnO photodetector were investigated. Intrinsic defects, VO, VZn, and Oi, were observed in the non-irradiated ZnO film from the photoluminescence spectroscopy. The neutron induced defects in the neutron irradiated ZnO film reacted with the VZn, Oi and grain boundary defects resulting in the degradation of mid band emissions. The p+-Si/n-ZnO heterojunction shows a rectifying factor of >1000 at 300 K under ±1.5 V and an avalanche breakdown voltage of ∼13 V. The impact ionization process is taken place in the p+-Si region revealed from the numerical calculation of the breakdown voltage of the p+-Si/n-ZnO heterojunction. The device can well perform as a linear and fast response photodetector with good repeatability. When operating under large reverse bias voltage, the p+-Si/n-ZnO can also act as an avalanching photodiode with the avalanche gain of ∼ 30. The p+-Si/n-ZnO detector continues to be operative as an avalanche photodiode as well after neutron irradiation with the fluence of 1015 n/cm2 unless the gain degenerating to ∼10, indicating the good neutron tolerance of the p+-Si/n-ZnO photodetector.

Design and Investigation of a Miniaturized Single-Layer ACS-Fed Dual Band Antenna for LTE and 5G Applications

Presently, a single compact antenna is expected to operate in multiple frequency bands, so that it may be used for multiple applications. In this regard, a compact asymmetric coplanar strip (ACS) fed monopole antenna was designed to operate in LTE band-40 and 5G mid band frequencies. To achieve the desired dual band frequency, meander line radiating structure was used. The uniplanar design with the ACS feed considerably reduced the antenna size to 19.25 × 10.5 × 1.6 mm3. This miniaturized dual band antenna can be easily integrated into circuit boards. The measured and simulated results provided a reflection coefficient (S&lt;sub&gt;11&lt;/sub&gt;) &lt; –15 dB, which made the antenna suitable for LTE band-40 and 5G mid-band communication applications.

Global climate model occultation lightcurves tested by August 2018 ground-based stellar occultation

Pluto's atmospheric profiles (temperature and pressure) have been studied for decades from stellar occultation lightcurves. In this paper, we look at recent Pluto Global Climate Model (GCM) results (3D temperature, pressure, and density fields) from Bertrand et al. (2020) and use the results to generate model observer's plane intensity fields (OPIF) and lightcurves by using a Fourier optics scheme to model light passing through Pluto's atmosphere (Young, 2012). This approach can accommodate arbitrary atmospheric structures and 3D distributions of haze. We compared the GCM model lightcurves with the lightcurves observed during the 15-AUG-2018 Pluto stellar occultation. We find that the climate scenario which best reproduces the observed data includes a N2 ice mid latitude band in the southern hemisphere. We have also studied different haze and P/T ratio profiles: the haze effectively reduces the central flash strength, and a lower P/T ratio both reduces the central flash strength and incurs anomalies in the shoulders of the central flash.

Design and Manufacturing of Super-Shaped Dielectric Resonator Antennas for 5G Applications Using Stereolithography

In this work, the inverted micro-Stereolithography (SLA) is used to show the potential of such additive manufacturing (AM) technology at prototyping super-shaped dielectric resonator antennas (S-DRAs) rapidly and accurately. The S-DRAs, which exhibit 3D complex geometries, were designed to operate at 3.5 GHz, suitable for the assessment of 5G communications in the mid band. Initially, a cross-starred-shaped S-DRA was designed and manufactured via the inverted micro-SLA by means of a photopolymer resin as material. As no information about the used material was available from literature and supplier, the dielectric properties of the photopolymer resin were characterized. Moreover, in the view of challenging further the SLA capability, several prototypes, based on the cross star shaped geometry but exhibiting a twist of variable angles along the longitudinal axis, were fabricated and tested. In order to compare the antennas performance in relation to the material volume and sizes, rectangular and cylindrical DRAs were also realized using same material and technology. Scattering parameter S11, gain, bandwidth (BW), efficiency and co- and cross-polarization of all antennas were measured. The experimental results showed that twisted S-DRAs exhibit same performance of the basic cross-starred-shaped antenna, due to the invariance to symmetry of the basic Gielis geometry. The measured gain is about 2.5 dB over a range of 1 GHz in the frequency range of interest; the BW measured for all S-DRAs is about 10%, whereas the efficiency is about 80% at 3.5 GHz. Finally, better performance in terms of bandwidth is shown by the S-DRAs, considering their dramatic volume reduction (~85%) compared to classic rectangular and cylindrical DRAs and other DRA examples already reported in the state of the art.

Bandwidth improvement of substrate integrated waveguide cavity-backed slot antenna with dielectric resonators

In the paper, a low profile substrate integrated waveguide based circular-shaped cavity-backed antenna is delineated to work at WLAN U-NII mid band and a slender rectangular slot is then placed at its center on the ground plane for radiation. The parent antenna radiates at 5.33 GHz with a gain of 4.9 dBi; depicting a narrow impedance bandwidth of 50 MHz. The antenna is modified by placing dielectric resonators of different shapes over the slot to enhance the bandwidth. The new antennas thus produced have an impedance bandwidth of 750 MHz with cylindrical-shaped and rectangular-shaped dielectric resonators which reflect bandwidth enhancement of 700 MHz for both the cases and an impedance bandwidth of 710 MHz with hemispherical-shaped dielectric resonator reflecting bandwidth enhancement of 660 MHz. The gain of the modified antennas is of the order of 4.7 dBi which basically indicates not much degradation in gain as compared to the parent antenna. All the antennas are delineated using Arlon AD270 substrate material with the results obtained after simulation juxtaposed with the ones obtained through measurement.

Split-ground Compact Ultra-wide Band Patch Antenna for Wireless LTE/UMTS Operations

The lower band and mid band ‘5G’ are known to use the frequencies in the range of 600 MHz – 6 GHz worldwide, especially 3.5GHz to 4.2GHz. A new modified multi slot compact planar ultra-wideband Microstrip patch antenna with a split ground plane has been proposed in this paper. The size of the antenna occupies volume of 34x30x1.7 (1734 mm^3) which has been designed on a FR4 epoxy substrate with dielectric constant of 4.4. In order to provide dual wideband characteristics, a ‘T and G ’shaped slots with split ground plane using line feeding structure has been used. The effects on the return losses v/s frequency for the antenna using different substrates with varying dielectric constants for the same dimensions has been studied in this paper. The proposed antenna operates in dual band with first band being a narrow band ranging from 1.92GHz to 2.06GHz and the second band is an ultra-wide band which ranges from 3.40 GHz to 9.6 GHz. The split ground plane and slot size variations in the T and G slot geometry helps in retrieving the dual bands. The proposed antenna is covering applications from LTE band No 40, UMTS IMT-2000, Wimax (3.5/5.55GHz), ISM WLAN 5.2/5.8GHz and RFID etc. The direct line feeding method which uses a 50Ω line with width of W=3mm has been used for the micro-strip line. With split ground plane, coupling between the slots plays role for achieving the good bandwidth. The analysis of return loss (dB), bandwidth, VSWR (Voltage Standing Wave Ratio) of patch antenna with different substrates and variation of the sizes of slots in shapes has been performed using HFSS tool [12] and results has been studied in this paper.

A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.

A Dual-Band CMOS Tunable Duplexer Employing a Switchable Autotransformer for Highly Integrated RF Front Ends

A dual-band CMOS duplexer employing a switchable autotransformer is proposed for highly integrated RF front ends in mobile phones. Because on-chip switches are used to change the length of the autotransformer, the inductance is sized for two different frequency ranges. It is designed to support both low-band (LB) mode from 0.7 to 0.9 GHz and mid-band (MB) mode from 1.7 to 2.0 GHz for cellular applications. With different inductances for LB and MB modes, transmitter (TX)-to-receiver (RX) isolation is achieved by using two separate balance networks for LB and MB. The duplexer is implemented in a 65 nm CMOS process. In LB mode, TX and RX insertion losses (ILs) are less than 4.3 dB, while TX-to-RX isolation is more than 50 dB. In MB mode, TX IL and RX IL are less than 4.5 dB, while TX-to-RX isolation is more than 50 dB. The proposed duplexer proves feasible structure to cover both LB and MB frequency ranges in cellular 3G/4G applications.

Quantitative Ultrasound Imaging for the Differentiation between Fresh and Decellularized Mouse Kidneys.

Decellularization is a technique that permits the removal of cells from intact organs while preserving the extracellular matrix (ECM). It has many applications in various fields such as regenerative medicine and tissue engineering. This study aims to differentiate between fresh and decellularized kidneys using quantitative ultrasound (QUS) parameters. Spectral parameters were extracted from the linear fit of the power spectrum of raw radio frequency data and parametric maps were generated corresponding to the regions of interest, from which four textural parameters were estimated. The results of this study indicated that decellularization affects both spectral and textural parameters. The Mid Band Fit mean and contrast were found to be the best spectral and textural predictors of kidney decellularization, respectively.

Investigation on tones due to self-excited oscillation within leading-edge slat cove at different angles of attack: Frequency and intensity

In an effort to understand the tonal noise characteristics of high-lift configurations, aero-acoustic experiments are conducted on a two-dimensional, three-element high-lift configuration model, with a stowed flap. As a less expensive aid to experimentation, the numerical simulation method is used to obtain flow parameters possibly related to tones. Experimental results show that the low-mid-frequency band tonal noise generated by the self-excited oscillation in the slat cove is the main far-field noise source. Based on the local flow field information obtained by numerical simulations, an improved empirical formula, as proposed by Terrocal, is adopted to predict the characteristic frequencies of self-excited oscillation within the slat cove, which agrees well with the tonal frequencies observed by wind tunnel testing at varying angles of attack. The intensity of these low to mid frequency band tones is also found to be dependent on the angle of attack, i.e., the primary tone of the self-excited oscillation switches from the second mode to the third mode, with increasing angles of attack. By investigating the local flow around the slat cove, the ratio of the shear layer length over the shear layer momentum thickness is determined, i.e., Lv/θ plays an important role in this transition of tonal intensity. As the angle of attack increases, both Lv and θ monotonous decrease, whereas Lv/θ increases and gives rise to a switch in the main characteristic frequency of the self-excited oscillation and a clear reduction in the overall sound pressure level.

Measurement of mid-frequency wavefront error for large optical components with ptychography.

In a high power laser system, the wavefront quality of large optical components in the mid spatial frequency band plays a critical role in system performance and safe operation. A simple and efficient method based on ptychography is used to measure mid-frequency wavefront error, which has the advantages of simple structure, strong anti-interference ability, flexible frequency-range selection, and low cost. It has excellent frequency response in the entire mid-frequency region. The transfer function is demonstrated to be greater than 0.7 at 1/2 Nyquist frequencies (8.33 mm-1) for 60mm field-of-view experimentally. The method has been successfully applied to the wedged focused lens (WFL) to achieve high-fidelity measurement. Without any auxiliary lens, the power spectrum of the WFL at the frequency of interest is obtained through large-aperture measurement. This technique is especially suitable for optical components difficult to be measured using interferometers and opens up a new perspective for measuring mid-frequency wavefronts.