Amplification Stage Research Articles

A 7.2–27.3 GHz CMOS LNA With 3.51 ±0.21 dB Noise Figure Using Multistage Noise Matching Technique

A wideband low-noise amplifier (LNA) with low and flat noise figure (NF) is presented in this article. For conventional wideband noise matching, the noise performance in the high-frequency region of the entire wideband is usually deteriorated due to the frequency-dependent nature of the minimum noise figure (NF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> ) for a MOSFET. To address this issue, a novel wideband noise matching approach aiming at noise matching in high band is proposed. This approach can reduce the NF in high band at the cost of a slight NF increase in low band, eventually achieving a low and flat NF and thus a better overall noise performance for a wideband LNA. In addition, the multistage noise matching technique is employed at high frequencies to further reduce the NF caused by the second amplification stage. To validate the proposed techniques, a two-stage LNA prototype was designed and fabricated using a 65 nm CMOS process. The experimental results indicate a peak gain of 16.6 dB with a −3 dB bandwidth (BW) from 7.2 to 27.3 GHz (a fractional BW of 116%). Within the entire band of interest, the simulated NF is low and almost constant (3.3–3.4 dB), while the measured NF falls within the range of 3.30–3.72 dB. Considering the uncertainty of NF measurement, a 0.21 dB NF flatness is one of the best results among the reported millimeter-wave wideband LNAs. The measured third-order input intercept point (IIP3) is −6 dBm at 20 GHz, while the power consumption is 13.2 mW. In addition, only two passive transformers are used in this design, leading to a compact chip core area (0.14 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ).

13.4 fs, 0.1 Hz OPCPA Front End for the 100 PW-Class Laser Facility

Here, we report the recent progress on the front end developed for the 100 PW-class laser facility. Using 3 stages of optical parametric chirped-pulse amplification (OPCPA) based on lithium triborate (LBO) crystals, we realized a 5.26 J/0.1 Hz amplified output with a bandwidth over 200 nm near the center wavelength of 925 nm. After the compressor, we obtained a pulse duration of 13.4 fs. As the compression efficiency reached 67%, this OPCPA front end could potentially support a peak power of 263 TW at a repetition rate of 0.1 Hz. To the best of our knowledge, among all the 100 TW-level OPCPA systems, it shows the widest spectral width, the shortest pulse duration, and it is also the first OPCPA system working at a repetition-rate mode.

Скрещивались ли неандертальцы массово с кроманьонцами? (С палеодилетантской точки зрения, но с учетом данных полногеномного секвенирования образцов современной и древней ДНК, а также на основе знаний используемых для этого технологий)

Neanderthals lived on the territory of present-day Western Europe for about 300 thousand years before the arrival of people of modern anatomical type, also called Cro-Magnons, about 50 thousand years ago. After that Neanderthal soon disappeared and what happened to them occupies the minds of many generations of paleoanthropologists, and over the years a large number of different versions have been put forward, according to one of which there was assimilation of Neanderthals by Cro-Magnons, which in fact does not correspond to reality. To the question whether interbreeding of these ancient hominins took place, one can confidently say only one thing – Neanderthal women did not contribute to the populations of modern humans, as can be seen from the differences in the nucleotide DNA sequences of inherited matrilineal mitochondrial genomes in Neanderthals and modern humans. The presence of some allelic variants of individual Neanderthal genes in the form of a number of single-nucleotide substitutions in the genomes of modern humans, detected by full-genome sequencing of nuclear DNA is still necessary an additional verification, which requires sequencing a larger number of complete genomes of ancient hominins with a large coverage. At the same time, the samples of modern genomes for such an analysis should be thoroughly increased, since only now about 8 billion very different modern unique "genomes" “live” on the Planet, and at least 100 million Neanderthals lived for all the years, also carrying unique genomes, although their polymorphism was somewhat lower. The article focuses on the fact that only diploid variant of genome, which can be designated as 6.0, should be considered a complete genome for human, whereas all currently sequenced genomes of ancient people are essentially quasi-haploid and can be designated as 3.0, based on the numbers of billions of pairs of nitrogenous bases in both double and single a set of chromosomes, respectively. Accordingly, the coverage during genome sequencing should be recalculated for their diploid status but not only for ancient organisms. It is also noted that the sequencing of ancient DNA urgently requires the development of new monomolecular sequencing methods, albeit characterized by lower productivity (speed), but independent of any stage of amplification and any enzymatic treatments, which will allow to establish the sequence of nucleotides as it is, including the recognition of uracils and other modifications of nitrogenous bases, as well as the absence of these in the DNA chains, which will certainly increase the accuracy of this process.

Spectral pedestal during the kilowatt-level amplification of a random fiber laser operating near the lasing threshold.

The amplification of random fiber lasers (RFLs) attracts much attention due to their unique characteristics such as wavelength flexibility and low coherence. We present that, in the kilowatt-level amplification of RFL operating near its lasing threshold, a broad and flat spectral pedestal can co-exist with the narrow spectral peak of RFL. This phenomenon is different from the case in the amplification of fixed-cavity laser seeds. Time-domain measurements show that the broad and flat spectral pedestal, which extends to long wavelengths, is composed of temporal pulses, while few temporal pulses exist in the narrow spectral peak. We attribute the spectral pedestal to intensity fluctuations from the random seed laser and modulation instability in the amplification stage. Control experiments reveal that the working status of the random seed laser and the effective length of the amplifier can influence the spectral bandwidth. By taking advantage of this phenomenon, we propose a novel approach to achieve a high-power broadband light source through the amplification of RFLs operating near the lasing threshold.

Multilayer metallic filters for Q/V band IMUX

AbstractCurrent designs of space IMUX filters are based on dual-mode circular waveguide cavities, on dielectric resonators or, at the lower end of the frequency spectrum, on coaxial resonators. This paper presents a new kind of IMUX filter aimed at high operating frequencies (Ka, Q, and V bands) which was developed in the frame of an ESA funded study named KALOS-DEVAQ. The new filter implements a quasi-elliptic frequency response and is characterized by simple geometry. The mechanical structure is composed of stacked metallic plates and it is well suited to be manufactured, at a low cost, with high accuracy. Despite the lower unloaded Q factor, the new configuration allows achieving a comparable flatness of insertion loss and group delay, thanks to the application of the pre-distortion technique. The increased insertion loss does not affect the system performances because it can be compensated by the amplification stages in the RF chain.

OpenOBS: Open‐source, low‐cost optical backscatter sensors for water quality and sediment‐transport research

AbstractOptical backscatter sensors (OBSs) are commonly used to measure the turbidity, or light obscuration, of water in fresh and marine environments and various industrial applications. These turbidity data are commonly calibrated to yield total suspended solids (TSS) or suspended sediment concentration (SSC) measurements for water quality, sediment transport, and diverse other research and environmental management applications. Commercial sensors generally cost &gt; $1000–3000. Here we leveraged simple, low‐cost microprocessors, electronics, and housing components to design and construct open‐source OBSs for &lt; $150 per unit. The circuit relies on a photodiode to sense backscattered light, two stages of signal amplification, and a high‐resolution analog‐to‐digital converter to read the detected signal. The instrument and logger utilize inexpensive, custom‐printed circuit boards with through‐hole soldering mounts; micro‐SD card reader and real‐time clock modules; and PVC housings with commercial end caps and epoxy‐potted diode emitter and receiver. All parts are readily and publicly available, and minimal experience in soldering and coding is required to build and deploy the sensor. In lab and field tests, standard deviations were comparable to those measured by commercial sensors (~ 2–3% of the mean for suspended muds and 20–30% for suspended sands). These open‐source sensors represent a useful advance in inexpensive sensing technology with broad applications across scientific and environmental management disciplines.

The Potential Use of Isothermal Amplification Assays for In-Field Diagnostics of Plant Pathogens.

Rapid, sensitive, and timely diagnostics are essential for protecting plants from pathogens. Commonly, PCR techniques are used in laboratories for highly sensitive detection of DNA/RNA from viral, viroid, bacterial, and fungal pathogens of plants. However, using PCR-based methods for in-field diagnostics is a challenge and sometimes nearly impossible. With the advent of isothermal amplification methods, which provide amplification of nucleic acids at a certain temperature and do not require thermocyclic equipment, going beyond the laboratory has become a reality for molecular diagnostics. The amplification stage ceases to be limited by time and instruments. Challenges to solve involve finding suitable approaches for rapid and user-friendly plant preparation and detection of amplicons after amplification. Here, we summarize approaches for in-field diagnostics of phytopathogens based on different types of isothermal amplification and discuss their advantages and disadvantages. In this review, we consider a combination of isothermal amplification methods with extraction and detection methods compatible with in-field phytodiagnostics. Molecular diagnostics in out-of-lab conditions are of particular importance for protecting against viral, bacterial, and fungal phytopathogens in order to quickly prevent and control the spread of disease. We believe that the development of rapid, sensitive, and equipment-free nucleic acid detection methods is the future of phytodiagnostics, and its benefits are already visible.

120 mJ, 1 kHz, picosecond laser at 515 nm.

We report on a 1 kHz, 515 nm laser system, based on a commercially available 230 W average power Yb:YAG thin-disk regenerative amplifier, developed for pumping one of the last optical parametric chirped pulse amplification (OPCPA) stages of the Allegra laser system at ELI Beamlines. To avoid problems with self-focusing of picosecond pulses, the 1030 nm output pulses are compressed and frequency doubled with an LBO crystal in vacuum. Additionally, development of a thermal management system was needed to ensure stable phase matching conditions at high average power. The resulting 515 nm pulses have an energy of more than 120 mJ with SHG efficiency of 60% and an average RMS stability of 1.1% for more than 8 h.

Mode-Field Matched Pump-Signal Combiner for High Power Fiber Laser in Advanced Manufacturing

Stable output and beam profile at high power laser operation is a prime requirement for precision high-end manufacturing. The stability of laser charateristics during power scaling in a single-oscillator is limited by several unavoidable non-linear effects. Hence, kW-level power scaling through multiple amplification stages or using signal combination are feasible solutions. In a master oscillator power amplifier (MOPA) architecture, pump-signal combiner with high pump coupling efficiency and low loss signal transmission maintaining seed beam quality during coupling from a single mode fiber into a large mode area fiber, is an important component. In this respect, an effective method of fabricating mode-field matched pump-signal combiner has been presented employing a section of intermediate fiber, having adiabatically tapered core and uniform cladding, along with a conventional signal fiber (termed hybrid signal fiber) inside the input fiber bundle to obtain effective mode-field matching of signal light in between the input fiber bundle and the output fiber. Additionally a taper-less signal combiner design has been proposed for scaling laser power through incoherent combination. The reduced-clad signal fiber with low loss core guidance supports bundling of the input fibers inside an economic low-OH silica tube to obtain good transmission efficiency and beam profile.

L-band cryogenic radio astronomy receiver front-end of the Square Kilometre Array

This paper describes the design and measured performance of the band 2 (L-band, 950 MHz–1760 MHz) cryogenic receiver front-end of the Square Kilometre Array (SKA) radio telescope dish array. The system comprises a wide flare-angle axially corrugated conical horn, a dual linearly polarized orthogonal mode transduce, a noise injection directional coupler, and two amplification stages. Its compact design and cryogenic cooling allow for a very low receiver noise temperature, and it presents another step in the continuous improvement of the noise temperature performance. A Gifford–McMahon cooler physically cools the OMT with its integrated directional coupler to around 70 K, and the first stage low-noise amplifier to about 15 K. A bespoke measurement setup was designed to measure the system’s performance. The measured receiver noise is about 6 K across the frequency band.

Molecular Beacon Assay Development for Severe Acute Respiratory Syndrome Coronavirus 2 Detection.

The fast spread of SARS-CoV-2 has led to a global pandemic, calling for fast and accurate assays to allow infection diagnosis and prevention of transmission. We aimed to develop a molecular beacon (MB)-based detection assay for SARS-CoV-2, designed to detect the ORF1ab and S genes, proposing a two-stage COVID-19 testing strategy. The novelty of this work lies in the design and optimization of two MBs for detection of SARS-CoV-2, namely, concentration, fluorescence plateaus of hybridization, reaction temperature and real-time results. We also identify putative G-quadruplex (G4) regions in the genome of SARS-CoV-2. A total of 458 nasopharyngeal and throat swab samples (426 positive and 32 negative) were tested with the MB assay and the fluorescence levels compared with the cycle threshold (Ct) values obtained from a commercial RT-PCR test in terms of test duration, sensitivity, and specificity. Our results show that the samples with higher fluorescence levels correspond to those with low Ct values, suggesting a correlation between viral load and increased MB fluorescence. The proposed assay represents a fast (total duration of 2 h 20 min including amplification and fluorescence reading stages) and simple way of detecting SARS-CoV-2 in clinical samples from the upper respiratory tract.

An isothermal, non-enzymatic, and dual-amplified fluorescent sensor for highly sensitive DNA detection

Abstract Sensitive DNA assays are of importance in life science and biomedical engineering, but they are heavily dependent on thermal cycling programs or enzyme-assisted schemes, which require the utilization of bulky devices and costly reagents. To circumvent such requirements, we developed an isothermal enzyme-free DNA sensing method with dual-stage signal amplification ability based on the coupling use of catalytic hairpin assembly (CHA) and Mg2+-dependent deoxyribozyme (DNAzyme). In this study, the sensing system involves a set of hairpin DNA probes for CHA (ensuring the first stage of signal amplification) as well as ribonucleobase-modified molecular beacons that serve as activatable substrates for DNAzymes (warranting the second stage of signal amplification). An experimentally determined detection limit of about 0.5 pM is achieved with a good linear range from 0.5 to 10 pM. The results from spiked fetal bovine serum samples further confirm the reliability for practical applications. The non-thermal cycling, enzyme-free, and dual-amplified features make it a powerful sensing tool for effective nucleic acid assay in a variety of biomedical applications.

Impact of the hole orientation of asymmetric GEM foils on the performance of single and triple GEM detectors

The Gas Electron Multiplier (GEM) foil is an amplification stage that has been introduced to overcome the problem of discharges observed in gaseous detectors. There are two major production techniques of GEM foils: double-mask and single-mask etching. Despite being an effective method, an asymmetry is observed between the top and bottom diameters of GEM holes in single mask technique compared to double mask one. In this paper we describe extensive simulations and measurements to study this hole asymmetry and its effect on the performance of GEM based detectors. The experimental data is collected using GEM foils of various hole geometries and orientations. In simulations, the same dimensions are used to study the properties of the detector. Simulations are performed with the Garfield++ simulation package along with ANSYS for creating the geometry of the GEM foils as well as the triple-GEM detector and the meshing needed for the field calculations. The simulation results match the observations from experimental studies. The gains measured with single and triple-GEM detectors are lower if asymmetric foils are oriented with the smaller diameters towards the readout plane. Detailed simulation of the amplification and collection steps indicates that the lower gain is attributed to a loss of electrons at the GEM3 foil for the first time.

Tm:YAG single-crystal fiber laser

In this Letter, to the best of our knowledge, we present the first thulium (Tm) single-crystal fiber (SCF) laser with free-space propagation of the laser beam only. The SCF is equipped with diffusion-bonded end caps of undoped YAG for better thermal management and enhancement of pump guiding. By utilizing mode matching and pump guiding in different SCF parts, an output power of 9.1 W is achieved at ∼2.02µm with a slope efficiency of 49.4%. This straightforward approach, which is also simple to realize and is based on combining the advantages of fiber-geometry structure and crystalline properties of Tm:YAG, is expected to be useful for 2 µm amplification stages in different time formats as well.

Enhancement of the X-Arapuca photon detection device for the DUNE experiment

In the Deep Underground Neutrino Experiment (DUNE), the VUV LAr luminescence is collected by light trap devices named X-Arapuca, sizing ∼ (480 × 93) mm2.Six thousand of these units will be deployed in the first DUNE ten kiloton far detector module. In this work we present the first characterisation of the photon detection efficiency of an X-Arapuca device sizing ∼(200 × 75) mm2 via a complete and accurate set of measurements along the cell longitudinal axis with a movable 241Am source. The MPPCs photosensors are readout by a cryogenic trans-impedance amplifier to enhance the single photoelectron sensitivity and improve the signal-to-noise while ganging 8 MPPC for a total surface of 288 mm2. Moreover, we developed a new photon downshifting polymeric material, by which the X-Arapuca photon detection efficiency was enhanced of about +50% with respect to the baseline off-shell product deployed in the standard device configuration. The achieved results are compared to previous measurements on a half size X-Arapuca device, with a fixed source facing the center, with no cold amplification stage, and discussed in view of the DUNE full size optical cell construction for both the horizontal and the vertical drift configurations of the DUNE TPC design and in view of liquid Argon doping by ppms of Xe. Other particle physics projects adopting Liquid Argon as target or active veto, such as Dark Side and LEGEND or the DUNE Near Detector, may take advantage of this novel wavelength shifting material.

Development of a High-Resolution Digital Beam Position Processor for the Hefei Advanced Light Facility Preresearch Project

A digital beam position processor (DBPP) with high resolution is required and developed for the Hefei Advanced Light Facility Preresearch Project to measure the orbit information and control the beam orbit jitter within one-tenth of the beam size. In this article, the design of the developed processor is presented in detail. Special attention is given to the analog part of the processor for a small noise figure and the calibration method for acceptable long-term stability. Different from the traditional calibration method using only the quasi-crossbar switch, our method combines temperature compensation attenuators, static digital attenuators, and the quasi-crossbar switch to a compound dynamic calibration method. In addition, a design of a switchable amplification stage is adopted to reduce the noise figure. A test stand, specially designed for the calibration and tests of the processor, is described. The initial laboratory tests show that the DBPP has a resolution of ~500 nm for turn-by-turn position, ~90 nm for fast acquisition at 5.03 kS/s rate, and ~30 nm for slow acquisition at 9.83-S/s rate, at a simulated beam current of about 500 mA. The alternative tests of the processor at Hefei light source-II verify the performance.

3'-Terminal Repair-Powered Dendritic Nanoassembly of Polyadenine Molecular Beacons for One-Step Quantification of Alkaline Phosphatase in Human Serum.

Alkaline phosphatase (ALP) is an important hydrolase with crucial roles in biological processes, and the dysregulation of ALP may cause various human diseases. The conventional ALP assays usually involve cumbersome procedures with poor sensitivity. Herein, taking advantage of intrinsic superiorities of molecular beacons (MBs) and unique features of terminal deoxynucleotidyl transferase (TdT), we demonstrate for the first time the 3'-terminal repair-powered dendritic nanoassembly of polyadenine (A) MBs for one-step quantification of ALP in human serum. When ALP is present, it catalyzes 3'-terminal dephosphorylation of poly-A MBs to induce TdT-mediated template-free polymerization, generating long chains of polythymidine (T) sequences. The long poly-T chains can function as the anchoring templates to hybridize with many poly-A MBs, leading to the unfolding of loop structures and the dissociation of FAM/BHQ1 pairs (the 1st amplification stage). Subsequently, all 3'-hydroxylated poly-A MBs can be extended with the assistance of TdT to generate the branched long poly-T chains, leading to the hybridization of more poly-A MBs and the dissociation of more FAM/BHQ1 pairs (the 2nd amplification stage). Through multiple rounds of extension, assembly, and activation of poly-A MBs, dendritic DNA nanostructures are automatically formed, resulting in the dissociation of abundant fluorophores from the FAM/BHQ1 pairs to generate an exponentially amplified fluorescence signal (the nth amplification stage). This strategy possesses high sensitivity and excellent specificity, and the detection limit can reach 1 cell. Moreover, it can evaluate kinetic parameters, screen inhibitors, estimate cellular inhibition effects, and measure ALP in human serums.

A novel electrochemical biosensor for lung cancer-related gene detection based on copper ferrite-enhanced photoinitiated chain-growth amplification

We reported an electrochemical biosensor via CuFe2O4-enhanced photoinitiated chain-growth polymerization for ultrasensitive detection of lung cancer-related gene. In this work, photoinitiated atom transfer radical polymerization (ATRP) was applied to amplify the electrochemical signal corresponding to lung cancer-related gene, and polymerization was triggered off under the illumination of blue light which was involved in copper-mediated reductive quenching cycle. At the same time, CuFe2O4–H2O2 system was also activated to enhance polymerization based on the photocatalysis of CuFe2O4, which was based on the reaction between •OH and methacrylic monomers to generate carbon-based radicals. Numerous ferrocene-based polymer was graft onto electrode surface through this amplification stages. The limit of detection was low to 1.98 aM (in 10 μL, ∼11.9 molecules) (R2 = 0.998) with a wide linear range from 0.1 fM to 10 pM. This strategy made a good trade-off between cost-effectiveness and sensitivity, and it also presented a high selectivity and anti-interference. In addition, the operation was greatly simplified and detection time was also shortened, which endowed this electrochemical DNA biosensor great application potential.

Coding Efficiency Enhancement Using Time Interleaved Level Splitting and Optimized Multi-Level Delta Sigma Modulation in Digital Transmitter

This paper proposes a novel scheme for energy-efficient transmitter design using optimized multi-level DSM (OML-DSM) along with time-interleaved level splitting technique. This scheme significantly improves the overall transmitter efficiency by providing high coding efficiency (CE) at the DSM stage and high drain efficiency (DE) at the amplification stage. The position of quantization level and quantization level selection window range is optimized in OML-DSM to achieve better CE compared to conventional multi-level DSM. These optimized multi-level signals are further split into bi-level signal streams using time-interleaved level splitting technique to improve the DE at the amplification stage. A 10 MHz LTE signal with 12 dB PAPR is used for simulation and measurement purposes. For hardware validation, 6-level OML-DSM is applied, which converts the 10 MHz LTE signal into six quantization levels and level splitter split these multi-levels into three bi-level signal streams with different magnitude and power levels. These bi-level signal streams are amplified using class-E SMPAs. The output of SMPAs is combined with Gysel unequal power combiner. Hardware results show that the CE and channel efficiency is improved by 18.7%, and 11.4%, respectively, compared to conventional 6-level DSM. The measured EVM is 2.2%, which shows good in-band performance.

A Three-Stage Comparator and Its Modified Version With Fast Speed and Low Kickback

This brief presents a three-stage comparator and its modified version to improve the speed and reduce the kickback noise. Compared to the traditional two-stage comparators, the three-stage comparator in this work has an extra amplification stage, which enlarges the voltage gain and increases the speed. Unlike the traditional two-stage structure that uses pMOS input pair in the regeneration stage, the three-stage comparator makes it possible to use nMOS input pairs in both the regeneration stage and the amplification stage, further increasing the speed. Furthermore, in the proposed modified version of three-stage comparator, a CMOS input pair is adopted at the amplification stage. This greatly reduces the kickback noise by canceling out the nMOS kickback through the pMOS kickback. It also adds an extra signal path in the regeneration stage, which helps increase the speed further. For easy comparison, both the conventional two-stage and the proposed three-stage comparators are implemented in the same 130-nm CMOS process. Measured results show that the modified version of three-stage comparator improves the speed by 32%, and decreases the kickback noise by ten times. This improvement is not at the cost of increased input referred offset or noise.