Efficient Amplifier Research Articles

USP15 promotes cGAS activation through deubiquitylation and liquid condensation.

Double-stranded DNA (dsDNA) is recognized as a danger signal by cyclic GMP-AMP synthase (cGAS), which triggers innate immune responses. cGAS activity must be properly regulated to maintain immune homeostasis. However, the mechanism by which cGAS activation is controlled remains to be better understood. In this study, we identified USP15 as a cGAS-interacting partner. USP15 promoted DNA-induced cGAS activation and downstream innate immune responses through a positive feedback mechanism. Specifically, USP15 deubiquitylated cGAS and promoted its activation. In the absence of DNA, USP15 drove cGAS dimerization and liquid condensation through the USP15 intrinsic disordered region (IDR), which prepared cGAS for a rapid response to DNA. Upon DNA stimulation, USP15 was induced to express and boost cGAS activation, functioning as an efficient amplifier in innate immune signal transduction. In summary, the positive role played by USP15-mediated cGAS activation may be a novel regulatory mechanism in the fine-tuning of innate immunity.

PAPR Analysis of OFDM using Partial Transmit Sequence Method

Orthogonal Frequency Division Multiplexing (OFDM) is one of the most widely used multicarrier transmission and effective technologies in today's communication networks. OFDM has many benefits and drawbacks. High Peak to Average Power Ratio (PAPR) is one of its main drawbacks. The spectral efficiency of the high-power amplifiers decreases with increasing PAPR. Therefore, maintaining a wireless system's efficiency is required to lower the PAPR. A possible method for lowering the high PAPR in OFDM systems is Partial Transmit Sequence (PTS). PTS generates a number of candidate signals, and the best signal with the lowest PAPR is chosen for transmission. The results shows that the PTS technique achieves greater PAPR minimization with less complexity. MATLAB simulation has been used to examine the OFDM system's PSD, spectral efficiency, BER performance, and PAPR analysis.

On the Fast DHT Precoding of OFDM Signals over Frequency-Selective Fading Channels for Wireless Applications

Due to high power consumption and other problems, it is unlikely that orthogonal frequency-division multiplexing (OFDM) would be included in the uplink of the future 6G standard. High power consumption in OFDM systems is motivated by the high peak-to-average power ratio (PAPR) introduced by the inverse Fourier transform (IFFT) processing kernel in the time domain. Linear precoding of the symbols in the frequency domain using discrete Hartley transform (DHT) could be used to minimise the PAPR problem, however, at the cost of increased complexity and power consumption. In this study, we minimise the computation complexity of the DHT precoding on OFDM transceiver schemes and the consequent power consumption. We exploit the involutory properties of the processing kernels to process the DHT and IFFT as a single-processing block, thus reducing the system complexity and power consumption. These also enable a novel power-saving receiver design. We compare the results to three other precoding schemes and the standard OFDM scheme as the baseline; while improving the power consumption efficiency of a Class-A power amplifier from 4.16% to 16.56%, the bit error ratio is also enhanced by up to 5 dB when using a 12—rate error-correction coding and 7 dB with interleaving.

Investigation of terahertz pulse generation in semiconductors pumped at long infrared wavelengths

We present designs of semiconductor contact grating high energy terahertz pulse sources pumped by femtosecond pulses in the 1 to 5 µm wavelength range. Nearly wavelength-independent diffraction efficiencies as high as 69% and 75% in the ± 1 st diffraction orders in the transverse electric field polarization state were predicted in GaAs and GaP, respectively, based on a rectangular grating. Numerical simulations—including, for the first time, to our knowledge, the effects of both a nonlinear refractive index and free carrier absorption—were performed to investigate the possible advantage of using longer pumping wavelengths to suppress the two- to seven-photon absorption. Conversion efficiency larger than 1.0% is predicted for both crystals. We also recognized that the nonlinear refractive index and the wavelength-dependent optical parametric amplifier efficiency can significantly reduce the overall terahertz generation efficiency; thus, optimum pump wavelengths exist for the highest conversion efficiency, which are 2 and 3 µ m for GaP and GaAs, respectively.

Guest Editorial Low-Cost Wide-Angle Beam-Scanning Antennas

One of the key antenna requirements in many modern wireless systems for communications and sensing is wide-angle beam-scanning <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . The traditional method to achieve wide-angle beam-scanning is to employ mechanically controlled reflectors or lenses, which are bulky, heavy, and suffer from slow beam scanning speed. Other important limitations of mechanical scanning antennas include the lack of multi-beam scanning capability and the ability to conform with non-planar structures (conformal geometries), which are essential in a number of emerging systems requiring very low-profile antennas. An alternative technique is to employ electronically beam-scanning antennas using passive or active phased arrays <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . Main disadvantages of phased arrays are high complexity, high power consumption, and high cost due to a large number of radio frequency (RF) or microwave phase shifters and T/R modules required. The problems worsen for phased arrays at millimeter-wave, sub-THz, and THz frequencies, due to significant losses in phase shifters and feed networks at higher frequencies combined with lower efficiency of power amplifiers <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> . The digital beamforming approach is even more costly and energy hungry due to the employment of large number of RF modules and digital devices <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> , <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[4]</xref> .

Comparative criteria for objective evaluation of the efficiency of RF power amplifiers

Objective comparison of radio frequency amplifiers, which are infinitely diverse in their parameters and purpose is a difficult engineering task. For its successful solution it is necessary to define objective criteria that allow to quantify qualitatively and quantitatively the scheme and mode of operation of the amplifier, without this assessment depending on the absolute values of current, voltage, power and parameters of active and passive elements in the electronic circuit.

Demonstration of Yb-Doped Fiber Amplifier Operating near 980 nm with the Slope Efficiency Close to the Theoretical Limit

In this paper, the scalability of slope efficiency of a Yb-doped fiber amplifier operating near 980 nm is studied with the core-pumping scheme. By means of numerical prediction, it is found that the theoretical limit of slope efficiency should be about 92.2%. Then, the experiment study is carried out. An 85.3% slope efficiency of emission around 980 nm is achieved with the seed light around 976.5 nm, and the strong in-band amplified spontaneous emission (ASE) is supposed to be a factor limiting the upscaling of slope efficiency. In order to suppress the in-band ASE, the double-wavelength fiber oscillator near 980 nm is fabricated and used as the seed source, with which the slope efficiency is elevated to 90.7%. Such slope efficiency is very close to the theoretical limit and sets a new record of slope efficiency for the Yb-doped fiber amplifier operating near 980 nm, to the best of our knowledge. It is also revealed that the suppression of in-band ASE should be of great importance to elevate the slope efficiency of a Yb-doped fiber amplifier operating near 980 nm.

A C-Band Broadband Asymmetric Doherty Power Amplifier Using Phase Compensation and Low Q Technology

In this paper, we present a monolithic microwave-integrated circuit (MMIC) asymmetric Doherty power amplifier (ADPA) using 0.25[Formula: see text][Formula: see text]m gallium-nitride (GaN) process with a compact chip size of 2.9 mm × 1.9 mm in wireless transmitters. Two different power amplifiers are adopted to solve the contradiction between the output power and efficiency of the conventional Doherty power amplifier (CDPA). In addition, phase compensation and low Q impedance inverting network (IIN) technology are used in the input and output matching networks, respectively, to expand the bandwidth of the entire ADPA. The post-layout simulation results show that the designed ADPA has a saturation output power 42.5 dBm with 800 MHz bandwidth from 6.6 to 7.4 GHz. The ADPA demonstrates 36.8–41.8% power-added efficiency (PAE), whereas 44–54% drain efficiency (DE) is achieved at saturation power.

Reducing PAPR with Low Complexity Filtered NOMA Using Novel Algorithm

Filtered Non-Orthogonal Multiple Access (F-NOMA) is a multi-carrier wave form and is considered a suitable contender for 5G radio. Peak to average power ratio (PAPR) is regarded as a major hurdle in the NOMA wave form because it hampers the efficiency of the power amplifier of the NOMA transmitter. In this study, a novel selective mapping (SLM) algorithm is used to minimize the PAPR of the NOMA. The conventional SLM increases the intricacy of the structure, and the projected SLM algorithm is applied to the transmitter part of the F-NOMA. Furthermore, we evaluate the performance of SLM on F-NOMA for 16, 64, and 256-Quadrature Amplitude Modulation (QAM) transmission methods. The parameters such as Bit Error Rate (BER), PAPR, power spectral density (PSD), and complexity are estimated and compared with different transmission patterns. The simulation outcomes of the work reveal that the optimal PAPR can be achieved by selecting the sub-block (S) and phase rotation elements (Ps). PAPR in F-NOMA achieves 1 dB gain in different QAM transmissions and its saving performance is 70.07%; however, complexity increases with an increase in modulation order.

Study on Er3+-Yb3+ co-doped La2O3–Al2O3 glasses for C-band optical waveguide amplifier with high luminous efficiency and low pump threshold

Efficient planar optical waveguide amplifiers at C-band are critical to the development of silicon photonics. In order to overcome the problem of low utilization efficiency of 980 nm pump for erbium-based planar optical waveguide amplifiers, an Er3+-Yb3+ co-doped La2O3–Al2O3 glass material for optical waveguide amplifiers was developed in this paper. While maintaining a high Er3+ doping concentration (∼1021 cm−3), the utilization efficiency of the material for 980 nm pumping is improved, so that the pump threshold of the waveguide amplifier fabricated with this material is lowered. Moreover, up-conversion and down-conversion luminescence are also suppressed in the material, resulting in a significant increase in the luminescence intensity of the C-band. A simple ridge waveguide simulation suggests that waveguide amplifiers fabricated by this material are expected to surpass the highest net gain reported so far for erbium-based planar waveguide amplifiers.

Synthesis, crystal structure, NMR and near infra-red luminescence studies of nine-coordinate Nd and Yb complexes based on fluorinated β‑diketone and a tridentate antenna chromophore, 2, 4, 6-Tris-(2-pyridyl)-s-triazine

Three nine-coordinate ternary complexes of La(III), Nd(III) and Yb(III) of general composition, [Ln(hfaa)3(tptz)] {hfaa = hexafluoroacetylacetone and tptz = 2, 4, 6-tris-(2-pyridyl)-s-triazine} are synthesised and comprehensively characterised. The X-ray single crystal structure and NMR studies show that the coordination structure of the complexes is nine-coordinate monocapped square antiprismitic in both solid and solution states with LnO6N3 (six oxygen atoms from three hfaa and three nitrogen atoms from one tptz) polyhedra. The complexes are stable in non-coordinating (chloroform) and coordinating (methanol) solvents as indicated by NMR spectrum where no dissociation of any ligand/s is observed. The longitudinal relaxation rate (ρ = 1/T1) is very fast in the cases of paramagnetic Nd(III) and Yb(III) complexes as compared to their diamagnetic La(III) analogue, suggesting their possible use as a relaxation probe in the magnetic resonance imaging. The complexes, on UV light excitation, show characteristic near infra-red emission transitions; 4F3/2→4Ij=9/2, 11/2, 15/2 of Nd(III) and 2F5/2→2F7/2 of Yb(III) ions. The tptz ligand has proved very efficient antenna as it increased the photoluminescence quantum yield of Nd(III) complex. The complexes showed considerable improved photophysical properties in NIR region, which could lead them as significant candidates in developing new materials for more efficient laser and optical amplifier systems, and windows transparent to the biological tissues

Long-distance distribution of qubit-qubit entanglement using Gaussian-correlated photonic beams

We investigate the deterministic generation and distribution of entanglement in large quantum networks by driving distant qubits with the output fields of a nondegenerate parametric amplifier. In this setting, the amplifier produces a continuous Gaussian two-mode squeezed state, which acts as a quantum-correlated reservoir for the qubits and relaxes them into a highly entangled steady state. Here we are interested in the maximal amount of entanglement and the optimal entanglement generation rates that can be achieved with this scheme under realistic conditions taking, in particular, the finite amplifier bandwidth, waveguide losses, and propagation delays into account. By combining exact numerical simulations of the full network with approximate analytic results, we predict the optimal working point for the amplifier and the corresponding qubit-qubit entanglement under various conditions. Our findings show that this passive conversion of Gaussian into discrete-variable entanglement offers a robust and experimentally very attractive approach for operating large optical, microwave, or hybrid quantum networks, for which efficient parametric amplifiers are currently developed.

Recent Advances in Aptasensors For Rapid and Sensitive Detection of Staphylococcus Aureus.

The infection of Staphylococcus aureus (S.aureus) and the spread of drug-resistant bacteria pose a serious threat to global public health. Therefore, timely, rapid and accurate detection of S. aureus is of great significance for food safety, environmental monitoring, clinical diagnosis and treatment, and prevention of drug-resistant bacteria dissemination. Traditional S. aureus detection methods such as culture identification, ELISA, PCR, MALDI-TOF-MS and sequencing, etc., have good sensitivity and specificity, but they are complex to operate, requiring professionals and expensive and complex machines. Therefore, it is still challenging to develop a fast, simple, low-cost, specific and sensitive S. aureus detection method. Recent studies have demonstrated that fast, specific, low-cost, low sample volume, automated, and portable aptasensors have been widely used for S. aureus detection and have been proposed as the most attractive alternatives to their traditional detection methods. In this review, recent advances of aptasensors based on different transducer (optical and electrochemical) for S. aureus detection have been discussed in details. Furthermore, the applications of aptasensors in point-of-care testing (POCT) have also been discussed. More and more aptasensors are combined with nanomaterials as efficient transducers and amplifiers, which appears to be the development trend in aptasensors. Finally, some significant challenges for the development and application of aptasensors are outlined.

A nanoreactor boosts chemodynamic therapy and ferroptosis for synergistic cancer therapy using molecular amplifier dihydroartemisinin

BackgroundChemodynamic therapy (CDT) relying on intracellular iron ions and H2O2 is a promising therapeutic strategy due to its tumor selectivity, which is limited by the not enough metal ions or H2O2 supply of tumor microenvironment. Herein, we presented an efficient CDT strategy based on Chinese herbal monomer-dihydroartemisinin (DHA) as a substitute for the H2O2 and recruiter of iron ions to amplify greatly the reactive oxygen species (ROS) generation for synergetic CDT-ferroptosis therapy.ResultsThe DHA@MIL-101 nanoreactor was prepared and characterized firstly. This nanoreactor degraded under the acid tumor microenvironment, thereby releasing DHA and iron ions. Subsequent experiments demonstrated DHA@MIL-101 significantly increased intracellular iron ions through collapsed nanoreactor and recruitment effect of DHA, further generating ROS thereupon. Meanwhile, ROS production introduced ferroptosis by depleting glutathione (GSH), inactivating glutathione peroxidase 4 (GPX4), leading to lipid peroxide (LPO) accumulation. Furthermore, DHA also acted as an efficient ferroptosis molecular amplifier by direct inhibiting GPX4. The resulting ROS and LPO caused DNA and mitochondria damage to induce apoptosis of malignant cells. Finally, in vivo outcomes evidenced that DHA@MIL-101 nanoreactor exhibited prominent anti-cancer efficacy with minimal systemic toxicity.ConclusionIn summary, DHA@MIL-101 nanoreactor boosts CDT and ferroptosis for synergistic cancer therapy by molecular amplifier DHA. This work provides a novel and effective approach for synergistic CDT-ferroptosis with Chinese herbal monomer-DHA and Nanomedicine.Graphical

Translational Detection of Indole by Complementary Cell-free Protein Synthesis Assay.

The information encoded in a single copy of DNA is processed into a plethora of protein molecules via the cascade of transcription and translation. Thus, the molecular process of gene expression can be considered an efficient biological amplifier from the viewpoint of synthetic biology. Cell-free protein synthesis (CFPS) enables the implementation of this amplification module for in vitro analysis of important biomolecules and avoids many of the problems associated with whole cell-based approaches. Here, we developed a method to analyze indole by using a combination of enzymatic conversion of indole and amino acid-dependent CFPS. In this method, indole molecules in the assay sample are used to generate tryptophan, which is incorporated into signal-generating proteins in the subsequent cell-free synthesis reaction. The activity of cell-free synthesized proteins was successfully used to estimate the indole concentration in the assay sample. In principle, the developed method could be extended to analyses of other important bioactive compounds.

Erbium-Doped Lithium Niobate Thin Film Waveguide Amplifier With 16 dB Internal Net Gain

Erbium-doped lithium niobate on insulator (Er:LNOI) has attracted enormous interest as it provides gain and enables integrated amplifiers and lasers on the lithium niobate on insulator (LNOI) platform. We demonstrate a highly efficient waveguide amplifier on Er:LNOI. The 2.58-cm long amplifier can achieve 27.94 dB signal enhancement, 16.0 dB internal net gain (6.20 dB/cm), −8.84 dBm saturation power, 4.59 dB/mW power conversion efficiency, and 4.49 dB noise figure at 1531.6 nm. Besides, thorough investigation on the pumping wavelength, pumping scheme, output power and noise figure have been performed to provide a comprehensive understanding on this novel waveguide amplifier. This work will benefit the development of a powerful gain platform and can pave the way for a fully integrated photonic system on LNOI platform.

Nd:YAG end-pumped zigzag multi-pass slab amplifier optimization: numerical and experimental study regarding the saturation effects.

A numerical modeling of Nd:YAG end-pumped zigzag multi-pass slab amplifier is developed. Spatial dependent rate equations have been solved taking into consideration the pump and laser beam saturation effects with regard to overlap correction of the signal path through gain medium. Based on our results, efficient amplifier structure with optimized output power could be designed with respect to the change in the number of signal beam-pass, doping concentration and slab length. In order to verify our modeling an experimental setup is designed.

Thulium-doped fluorotellurite glass fibers for broadband S-band amplifiers.

We demonstrated broadband S-band (1460-1530 nm) amplification in Tm3+-doped fluorotellurite glass fibers (TDFTFs) by using a 1400/1570 nm dual-wavelength pump technique. TDFTFs based on TeO2-BaF2-Y2O3 (TBY) glass were fabricated by using a rod-in-tube method. For an input signal power of 0 dBm (or 1 mW), a broadband positive net gain ranging from <1440 nm to 1546 nm was achieved in a 1.55-m-long TDFTF with a Tm3+ doping concentration of ∼4000 ppm, as the pump powers of the 1400 nm and 1570 nm lasers were 1.7 W and 0.14 W, respectively. The corresponding bandwidth for a net gain of >20 dB was ∼66 nm (1458-1524 nm), and the measured saturated output power was ∼24.84 dBm at 1490 nm. In addition, numerical simulation was performed by using the parameters of the TDFTFs and the pump lasers, and the noise figure was calculated to be <5.6 dB in the S band. Our results showed that the TDFTFs were promising gain media for constructing efficient broadband S-band fiber amplifiers.

Miller’s Compensation Techniques for a High Gain, High BW OP-AMP at 65 nm Technology

OP-AMPs find applications in different domains of electronics engineering including communications. There have been several OP-AMP configurations realized in the last decades for different target applications. But with the evolution of communication standards, to meet the demand for high data rate over the years, the requirement for a high frequency and high BW OP-AMP is gaining attention. This makes the design challenge much higher. This paper presents a two-stage CMOS amplifier that uses a frequency compensation method to facilitate higher BW. Different parameters like Gain, Gain bandwidth product (GBWP), Phase Margin, and Total Power dissipation are considered in this design. A step-by-step procedure for an efficient amplifier design is followed using frequency compensation. We have achieved a gain-bandwidth product (GBWP) of 110 MHz that is capable of driving large capacitive loads. It also achieves 77.7 dB gain and phase margin of 60° with the minimal noise of 2.27 μ^V/√ Hz and the slew rate of 20.12 V/ms

Analysis and design of class-E power amplifier considering MOSFET nonlinear capacitance

Class-E power amplifiers are integrated into many applications because their simple design and high performance. The efficiency of the power amplifier is significantly impacted by the nonlinear characteristic of the switching device, which is not analyzed clearly in theory. The nonlinear drain-to-source parasitic capacitance of the power transistor and the linear external capacitance are both contributed to the optimum conditions for obtaining the exact shunt capacitance. In this paper, a high-efficiency class-E power amplifier with shunt capacitance is designed with the consideration of both linear and nonlinear capacitance. Furthermore, a mathematical analysis is derived to calculate the component values in order to design the class-E power amplifier. Consequently, high power-added efficiency of 94.6% is obtained using MRF9030 MOSFET transistor with parameter of 4W output power and 13.56 MHz operating frequency. Finally, the measurement result of a linear class-E power amplifier circuit is obtained to compare and realize the efficiency of the proposed work.