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In this article, we report a compact and low‐profile GaN‐based broadband power amplifier using silicon interposer‐MMIC (iMMIC) technology. The iMMIC technology enables a GaN HEMT to be embedded in the silicon substrate, and passive circuit elements such as metal‐insulator‐metal (MIM) capacitors, spiral inductors, and thin film resistors to be implemented on the high‐resistivity silicon (HRS) substrate using standard integrated passive device (IPD) process, so that the final power amplifier is almost indistinguishable from a single GaN MMIC power amplifier. The RLC matched all‐pass network and LC ladder type low‐pass network are employed as the input matching network and output matching network, respectively. The proposed power amplifier has a Psat of 39.1 to 39.2 dBm with a power‐added efficiency (PAE) of 40% to 50.5% in the frequency range of 2.1 to 3.5 GHz under continuous wave (CW) input signal. The proposed iMMIC power amplifier occupies only 9.9 mm2. [ABSTRACT FROM AUTHOR]

This paper presents a method for designing a power amplifier for high efficiency Class-E broadband topology using a low- pass filter of a high order is presented. A study of the state of the art regarding the design of a power amplifier Class-E performed operating within the frequency band of 0.8 GHz to 1.5 GHz. In the design accordingly ensures the attenuation of the power of the second and third harmonic, critical to achieving high efficiency amplification criterion. The design equations and simulation were made in AWR Design Environment V13. The efficiency levels achieved were 74%, the efficiency of added power (PAE) 72% power gain was more than 8 dB across the band, a bandwidth of665 MHz, and the band of 60.8% was achieved, with an efficiency drain and PAE above 50%. [ABSTRACT FROM AUTHOR]

In the quasistatic limit, Rayleigh scattering is investigated for a graded spherical metamaterial when the wavelength of light is larger than the particle diameter. As a theoretical model, we have exactly derived the dipole factor of the Rayleigh scattering electric field induced by the graded sphere metamaterial, whose permittivity is given by the graded Drude model. Our results show that the amplitude of scattering field can be controlled and remains very small over a broad frequency band by tuning the gradation profiles of particle permittivity. This implies that a broadband transparency of electric field is achieved by using graded metamaterials. Here, we offer a solvable example of very small Rayleigh scattering in a broad frequency band. [ABSTRACT FROM AUTHOR]

We report results on a dimensionally gradient magnetoelectric (ME) sensor that demonstrates high performance over a wide frequency range and a magnetic dc bias operating in the longitudinal-transversal mode. The design of the sensor is based on a piezoelectric bimorph structure and utilizes a laminate configuration with Pb(Zn1/3Nb2/3)0.2(Zr0.5Ti0.5)0.8O3 and Metglas as material layers. The wide-band behavior was characterized by a flat ME response over a wide range of magnetic dc biases corresponding to 60–215 Oe and frequencies corresponding to 7–22 kHz. By using tip mass, the wide-band frequency response was shifted to a lower frequency range of 5–14 kHz. The results show that the operating frequency range of the sensor can be easily shifted by changing the tip mass at the end of the composite. [ABSTRACT FROM AUTHOR]

• We present a broadband nanosecond superfluorescent fiber source (ns-SFS). • The impact of the active fiber' s length on the output spectrum of SFS is investigated theoretically and experimentally. • All-fiberized ns-SFS amplifier with average power of greater than 440 W, pulse energy of 17.6 mJ is achieved. In this work, we demonstrate a broadband nanosecond superfluorescent fiber source (ns-SFS) with an average power of several hundred watts and an adjustable repetition frequency of 25 kHz–100 kHz. To figure out a suitable active fiber length for ns-SFS seed, the impact of active fiber length on the output spectrum of SFS is investigated theoretically and experimentally. The results indicate an evident redshift in the central wavelength of output spectrum with increasing fiber length. By scaling the power of the ns-SFS seed employing three amplifier stages, the maximum average power and pulse energy are obtained with a value of 463 W, 17.6 mJ, respectively. To the best of our knowledge, this work is the first demonstration of a broadband ns-SFS amplifier with output power exceeding hundred watt and pulse energy exceeding 10 mJ. [ABSTRACT FROM AUTHOR]

We report accurate tuning of spectral peaks built up upon guiding of broadband light by annealed Si-rich silica layers with varying optical thickness. The optical wedges are characterized with various methods (photoluminescence, Raman spectroscopy, visible absorption, and x-ray photoelectron spectroscopy) showing that their properties change smoothly from point to point along the sample surface. As measured in the conventional transverse detection geometry, the annealed (1100 °C) Si-rich silica material exhibits well-known broad photoluminescence (PL) with maximum at ∼800 nm conventionally connected with Si nanocrystals. In the waveguiding detection geometry, the guiding of PL light by the silica layer containing Si nanocrystals is wavelength-dependent, and the detected spectrum exhibits narrow (down to 100 cm-1) and linearly polarized spectral peaks. As the central observation of the present work, these spectral peaks can be accurately tuned over the whole PL spectral region by moving the optical wedges across the laser beam. For our samples, the tuning coefficient is ∼150 cm-1/mm. It is shown that tuning of the transmission peaks is caused by change of both refractive index (from 1.6 to 1.9) and thickness (from 1.4 to 2.0 μm) of the prepared optical wedges. The propagation loss for the guided light is found to increase for shorter wavelengths and for materials with larger Si concentration. The propagation losses reliably below 0.5 cm-1 are observed in the broad spectral interval in sample areas with smaller Si concentrations. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A novel pole-tuning technique with T-type network for interstage bandwidth extension is proposed in this paper. By exploiting the proposed technique in interstage of amplifiers, the transfer function of each stage exhibits two dominant poles, achieving a flat gain-frequency response over an ultrawide bandwidth. For verification, a four-stage amplifier based on the pole-tuning technique with T-type network has been designed and implemented in a 65-nm bulk CMOS technology. The fabricated prototype achieves a peak gain of 9.5 dB at 122 GHz with a 3-dB bandwidth of more than 26 GHz and a fractional bandwidth of larger than 21.3%, while consuming a dc power of 62 mW. At the operating frequency of 125 GHz, the saturation output power and the output P1 dB are 8.6 and 4.6 dBm, respectively. The chip occupies a small silicon area of 0.27 mm2 including all testing pads with a core size of only 0.105 mm2. The proposed amplifier is suitable for short-distance data center communication as one of the key building blocks.

A novel dual-transformation simplified real frequency technique is proposed in this paper to synthesize a broadband Doherty power amplifier (DPA). The proposed method can realize the co-design of the carrier and peaking output matching networks to achieve dual-impedance transformation at back-off (BO) and saturation simultaneously. To realize this method, a generalized driving point function with different loads of the matching network is proposed, and weight factors are adopted to combine the separate target functions to form a united one. Compared with conventional designs, no initial guess is required and additional compensating lines are eliminated to improve the performance of the DPA. Based on the proposed technique, a broadband DPA is designed and fabricated across 2.2-3.7 GHz (51% fractional bandwidth). The measurement results show that the designed DPA has a 6-dB BO efficiency of 45%-53% and a saturated output power of 43-44.6 dBm over 1.5 GHz bandwidth. Various modulated signals including 80-MHz long-term evolution-advanced signal and concurrent dual-band signal are employed to validate the DPA. In this way, the DPA can achieve an average efficiency of 45.3%-55.9% at 6.5-dB BO with the adjacent channel leakage ratio levels better than -48.6 dBc by utilizing digital predistortion.

In this article, we present a novel technique to build digital predistorters that can linearize broadband power amplifiers (PAs) using reduced sampling rates. In contrast to conventional digital predistortion (DPD) where oversampling is necessary to avoid aliasing effect, the proposed method cancels the aliasing distortion using a sliced multistage cancellation scheme. A large reduction of sampling rate can be achieved in digital implementation of DPD, significantly reducing power consumption and implementation cost. Experimental results show that a DPD with a sampling rate of merely $1.5\times $ , instead of $5 \times $ , signal bandwidth, can still produce satisfactory performance within the linearization bandwidth but consume only one-third of power, compared with that using the conventional approaches. The proposed technique provides a promising solution for the next-generation 5G systems, where large signal bandwidths are required. [ABSTRACT FROM AUTHOR]

In this work, two copper-based biometamaterials were engineered using leaves of water cabbage (Pistia stratiotes) and purple bauhinia (Phanera purpurea) as templates. The copper sputtering was implemented to produce a thin copper film on the surface of leaves. The scanning electron microscopy (SEM) images exhibited the root hair-like nanostructure of water cabbage leaf and single comb-like nanostructure of purple bauhinia leaf. In spite of copper coating, the leaf surfaces of water cabbage and purple bauhinia were black and exhibited excellent light absorption at visible and near infrarrred wavelengths. It was estimated that these two types of leaves could absorb roughly 90% of light. Finite-difference time-domain (FDTD) calculations predicted the low reflectance stemming from the leaf nanostructures and copper coating layer. Because of the low cost of copper as a coating metal and simple procedure, this can be a promising method for quick fabrication of a thin copper film on the leaf nanostructure for application in blackbody or as the light absorbers. [ABSTRACT FROM AUTHOR]

In this paper, the design of a Broadband Power Amplifier for UHF applications is presented. The proposed BPA is based on ATF13876 Agilent active device. The biasing and matching networks both are implemented by using microstrip transmission lines. The input and output matching circuits are designed by combining two broadband matching techniques: a binomial multi-section quarter wave impedance transformer and an approximate transformation of previously designed lumped elements. The proposed BPA shows excellent performances in terms of impedance matching, power gain and unconditionally stability over the operating bandwidth ranging from 1.2 GHz to 3.3 GHz. At 2.2 GHz, the large signal simulation shows a saturated output power of 18.875 dBm with an output 1-dB compression point of 6.5 dBm of input level and a maximum PAE of 36.26%. [ABSTRACT FROM AUTHOR]

Ho3+/Yb3+ co-doped tellurite–germanate glasses with lower phonon energy (771 cm−1) were prepared by conventional melt-quenching method. The prepared samples were characterized by emission spectra, differential scanning calorimeter (DSC) curve, X-ray diffraction (XRD) pattern, and Raman spectra. The DSC curve shows that the sample has a good thermal stability, in which the ΔT is 202 °C. Compared to the recently reported tellurite glasses, the ΔT was increased by approximately 24%. Under the 980 nm laser excitation, it was found that the full width at half maximum (FWHM) of the sample at 2.0 µm was 190 nm. Compared with the reported glasses for this type, the value was effectively improved. Meanwhile, the FWHM of the sample at 4.1 µm was 285 nm, which has not been reported yet. This indicates that Ho3+/Yb3+ co-doped tellurite–germanate glass has a great application prospect in mid-infrared broadband fiber amplifiers. [ABSTRACT FROM AUTHOR]

In this article, a 1.7–2.6-GHz broadband power amplifier (PA) was proposed using the generalized quasi-Chebyshev lowpass matching approach, which was directly composed of step-impedance transmission lines (SITLs). First, the complete design theory for the introduced step-impedance matching network was provided with the detailed design equations. The impedance of the SITLs can be calculated directly based on the specified bandwidth, maximum allowable return loss, and impedance-transforming ratio. The electrical length of SITLs was utilized to adjust the harmonic impedances to perform a PA high-efficiency region. For demonstration, a PA using the 10-W gallium nitride high electron mobility transistor (GaN HEMT) with the measured drain efficiency (DE) of 65%–78% from 1.7 to 2.6 GHz was achieved. A good agreement between the simulated and measured results can be observed. [ABSTRACT FROM AUTHOR]

A bismuth‐doped compound glass‐based microsphere laser is reported. The fluorescence luminescence of the bismuth‐doped compound glass is measured over an ultra‐broad wavelength range of 1100 to 1700 nm excited using an 808 nm pumping source. The glass microsphere was fabricated using a CO2 laser heating the fiber near its melting temperature, and when coupled with the tapered silica fiber, yielded the 1310 nm laser emission pumped using an 808 nm laser diode. The 245 μW––low absorbed pumping threshold of the microsphere, 3.57 μW laser output and the tunable multiple wavelength emissions demonstrate great potential applications for use in near infrared broadband fiber amplifiers and tunable lasers. [ABSTRACT FROM AUTHOR]

In this article, a novel nested-mode power amplifier (NMPA) is proposed for highly efficient multi-octave applications. By introducing a group of nested guaranteed regions (GRs) at the fundamental and harmonic frequencies as the target design space, the difficulties caused by frequency overlapping in harmonically tuned multi-octave power amplifiers (PAs) can be overcome, leading to a self-consistent theory of multi-octave PAs. Furthermore, the methodology of constructing the proposed nested GRs is demonstrated based on a simplified numerical model. According to the methodology, the desired nested GRs can be constructed by following several well-defined closed-form steps. In addition, a feasible design methodology of the NMPA is established based on a simplified deembedding technique of packaged devices. Based on the proposed theory and design method, a 1–3100-MHz NMPA is designed and measured. According to the measured results, the designed PA exhibits 57.5–73.9% drain efficiency and 39–42.6-dBm output power across the band. Moreover, the linearity and linearizability of the designed NMPA are verified using up to 20-MHz-bandwidth-modulated signals across the designed band accompanied with a digital predistortion (DPD) procedure. To the best of our knowledge, this is the state-of-the-art performance of multi-octave broadband PAs. [ABSTRACT FROM AUTHOR]

Thulium-doped fiber amplifier is a very proficient broadband fiber amplifier in S-band. Silica-based TDFA is a popular choice due to some of its evident features such as non-toxic nature, easy splicing and simple assembling. In this work, we have simulated and optimized various TDFA's physical and operational parameters in order to obtain required gain spectra at different channel spacings. Further, a comparative study has been carried out between single and dual-pumped TDFAs. By using dual pumping scheme (1040 nm and 1000 nm) as fundamental source of excitation, maximum gain of 23.31 dB has been achieved at 1468.8 nm in region spanning 1400 nm to 1470 nm wavelengths with noise figure of 3.72 dB. [ABSTRACT FROM AUTHOR]

The research of a single stage broadband solid-state power amplifier based on ATF13876 transistor, which operates in the frequency ranging from 1.25 GHz ~3.3 GHz is presented in this paper. To achieve the broadband performance of the operating bandwidth, a multi-section quarter wave impedance transformer and an approximate transformation of previously synthesized lumped elements into transmission lines are adopted. With neatly design of broadband matching networks and biasing circuit, excellent matching performances and unconditionally stability are achieved over the whole operating bandwidth with a maximum gain of 17.2 dB. the large signal simulation shows that the proposed circuit reaches a saturated output power of 18.12 dBm with a maximum PAE of 27.55% and a 1-dB compression point at 5 dBm input power level. Considering the wide frequency coverage, the features of the proposed design compares favorably with the contemporary state-of-the-art. [ABSTRACT FROM AUTHOR]

A microfabricated planar 0.22 THz TWT is being investigated as a high power, broadband amplifier for ultra-broadband wireless communication, imaging and remote sensing. Planar staggered double-vane-loaded rectangular waveguide slow wave structure (SDV-SWS) is selected for the 0.22 THz TWT because of its wide bandwidth, high impedance and low loss, easy fabrication using MEMS technologies with high precision and surface finish, and inherent compatibility for operation with sheet electron beam. A simplified approach is presented for determining initial design parameters of the SDV-SWS of wide bandwidth and high impedance. The initial design parameters of the SDV-SWS are used for analytically determining the dispersion and the impedance characteristics of the structure which are found comparable with the simulated characteristics by the 3D e.m. field simulator CST code. The SDV-SWS is designed for a planar 0.22 THz TWT with a sheet beam of beam voltage 20 kV and beam current 100 mA. In-house developed large signal analysis code (SUNRAY-p) is used to analyse RF performance of the planar TWT over the band. The RF performance of the 0.22 THz TWT as determined using SUNRAY-p code is found comparable with the simulated results by the CST code over the frequency band. [ABSTRACT FROM AUTHOR]

In this paper, an innovative approach to achieve broadband linear power amplifier (PA) with a continuous broadband is presented. The proposed method mainly depends on the theory of control of intermodulation products and harmonics. This method results in a continuous sweet spots over a wide bandwidth. Based on the continuous sweet spots, a suboptimal solution is derived for improving the efficiency and linearity of broadband PAs. To verify the effectiveness of this method, one broadband PA operating over 4.5–5.5 GHz is developed and measured, it indicates that the peak output power of the PA is 35–57 dBm for a small signal input with a gain of 12 dB, and the peak drain efficiency (DE) of the PA is larger than 57% over the whole working band. However, when the PA is stimulated by a 5 MHz two-tone signal input, we observe that the DE keeps above 38% under the condition of the measured third-order intermodulation distortion (IMD3) is not larger than − 3 0 dBc. [ABSTRACT FROM AUTHOR]

Octahedral CeO 2 :Er3+ nanocrystals were successfully prepared using a simple hydrothermal method, and the structural and excitation dependent emission properties were investigated in detail. Green (2H 11/2 , 4S 3/2 → 4I 15/2), red (4F 9/2 → 4I 15/2) and NIR (4I 11/2 → 4I 15/2 and 4I 13/2 → 4I 15/2) emission were observed under 980 nm laser diode excitation. The optimal Er3+ doping concentration was 3 mol%, and the effect of Li+ co-dopants with concentration up to 10 mol% on microstructure and emission was investigated. However, for the samples excited under 352 nm down-conversion excitation, the Vis-NIR spectral distribution induced distinct changes related to the excitation mode. Remarkably high enhancement of 1532 nm NIR emission about 12 times was achieved by codoping with Li+ ions, which make CeO 2 :Er3+,Li+ nanocrystal a promising candidate for optical amplifier using broadband UV pumping. The possible mechanism of above up-and down-conversion emission and energy transfer process has also been discussed. [ABSTRACT FROM AUTHOR]

Radiation-level 1D 2 adaptive fluorophosphate glasses (NBFP) have been exhibited and relevant transition emissions of Pr3+ have been quantitatively characterized. Intense visible fluorescence is proved to generate from 1D 2 level principally and the quantum yield (QY) of emissions originating from this level is as high as 7.94% in 500–900 nm, indicating the decisive significance of the 1D 2 level in reddish-orange fluorescence of NBFP glasses. Effective broadband 1.47 μm near-infrared (NIR) emission ascribed to 1D 2 →1G 4 transition has been observed, meanwhile, the full-width at half-maximum is obtained to be 141 nm and the maximum stimulated emission cross-section is derived to be 5.75 × 10−21cm2, suggesting the effectiveness of the NIR emission from the initial level 1D 2 in the specific NBFP glasses. In view of absolute radiation parameters and fluorescence branch ratios, net emission photon number of the attractive NIR emission is expected to be 4.5 × 1014cps under 453 nm laser pumping with 82.05 mW power, and corresponding QY is anticipated to be 2.0%. High shortwave transparency and moderate phonon energy are confirmed to be two important indicators for exploring suitable host materials in achieving effective radiations from 1D 2 level of Pr3+, revealing the forward-looking applications of fluorophosphate glasses as broadband NIR amplifiers and irradiative luminescence sources. Image 1 [ABSTRACT FROM AUTHOR]

This paper presents the design of a broadband and high-power amplifier with bounded performance technique (BPT). Like the real frequency technique (RFT) or the simplified RFT (SRFT), BPT achieves broadband performance via matching at some in-band discrete real frequencies. It solves some design issues that are not addressed in the RFT and the SRFT. Among them are the inclusion of the design specifications in the device selection and design process and the possible degradation of operation metrics that are not optimized. BPT also avoids complicated analytic mathematics by using circuit prototypes. In this paper, we show the design of an amplifier with BPT. It has a 3-dB compression power of at least 100 W and a drain efficiency of at least 50% over the band 1–2.8 GHz or 94.7% fractional bandwidth. We also show the design of the same amplifier with the traditional SRFT and compare its expected performance with that designed with BPT. [ABSTRACT FROM AUTHOR]

A 6–18 GHz high-power amplifier (HPA) design in GaN on SiC technology is presented. This power amplifier consists of a two-stage corporate amplifier with two and four transistors, respectively. It has been fabricated on UMS using their 0.25 µm gate length process, GH25. A study of the suitable attachment method and measurement on wafer and on jig are detailed. This HPA exhibits an averaged output power of 39.2 dBm with a mean gain of 11 dB in saturation and a 24.5% maximum power added efficiency in pulse mode operation with a duty cycle of 10% with a 25 µs pulse width. [ABSTRACT FROM AUTHOR]

In this brief, a 0.1 to 23 GHz low-noise amplifier (LNA) employing a frequency-dependent feedback loop (FDFL) is presented. As predicted theoretically, the optimized FDFL enhances the bandwidth and the gain flatness in desired frequency band through purposely designing the feedback characteristics from negative to positive corresponding to the frequency. Based on the theoretical analysis of bandwidth enhancement, noise characteristic, and linearity of FDFL, an ultra-broadband LNA, utilizing the proposed technique, is designed and verified experimentally by a three-stage LNA chip implemented using a 0.15- $ {\mu }\text{m}$ GaAs pseudomorphic high electron-mobility transistor process. Measurement results show that the LNA obtains an average gain of 27.4 dB and noise figure of 2.7 to 4 dB in a frequency band from 0.1 to 23 GHz, with a compact chip area of only 1.36 mm2, including input/output testing pads. [ABSTRACT FROM AUTHOR]

The energy resolution of a single photon counting microwave kinetic inductance detector can be degraded by noise coming from the primary low temperature amplifier in the detector's readout system. Until recently, quantum limited amplifiers have been incompatible with these detectors due to the dynamic range, power, and bandwidth constraints. However, we show that a kinetic inductance based traveling-wave parametric amplifier can be used for this application and reaches the quantum limit. The total system noise for this readout scheme was equal to ∼2.1 in units of quanta. For incident photons in the 800–1300 nm range, the amplifier increased the average resolving power of the detector from ∼6.7 to 9.3 at which point the resolution becomes limited by noise on the pulse height of the signal. Noise measurements suggest that a resolving power of up to 25 is possible if the redesigned detectors can remove this additional noise source. [ABSTRACT FROM AUTHOR]

A broadband low-noise amplifier (LNA) using 0.13 μ m GaAs HEMT technology for Ku-band applications is presented in this paper. By introducing an improved self-bias architecture, the LNA is achieved with low noise figure (NF) and high power gain. Compared with traditional LNA, self-bias architecture can reduce DC supplies to single one, and the improved architecture proposed here also takes part in source matching to reduce the complexity matching networks for broadband applications. To verify, an LNA operating over 12–18-GHz bandwidth is fabricated. The measurement results, for all the 72 chips on the wafer, and their average values are in great accordance with the simulation results, with 25.5–27.5-dB power gain, 1.1–1.8-dB NF, 15–17.5-dBm output power at P 1 dB and with a chip size of 2 mm ∗ 1.5 mm. [ABSTRACT FROM AUTHOR]

This paper presents a broadband efficient power amplifier (PA) targeting sub-6-GHz 5G base station applications. Due to the demanding requirements in both peak-to-average power ratio (PAPR) and bandwidth in 5G systems, we employ a combination of both load and supply modulation for efficiency enhancement. Active matching, implemented using an RF-input load-modulated balanced amplifier (LMBA) architecture, enables efficient octave-bandwidth operation. Supply modulation, which is carrier frequency agnostic, is then used to further extend the back-off efficiency. This paper focuses on a study of supply modulation strategies for the load-modulated PA using an efficient GaN eight-level discrete supply modulator. To overcome the bandwidth limitations associated with discrete-level switching, a commutation rate reduction (CRR) filter is applied in digital baseband and its effects are analyzed theoretically and experimentally. The supply-modulated LMBA is characterized across 1.8–3.8 GHz with 100-MHz, 10-dB PAPR signals. An output power of 34 dBm with average composite (total) PAE ranging from 22.4% to 43.9% across the band is demonstrated, with an ACLR of about −50 dBc after digital predistortion. [ABSTRACT FROM AUTHOR]

Identifying lateralization of bilateral temporal lobe epilepsy (TLE) is a challenging issue; scalp electroencephalography (EEG) and routine band electrocorticography (ECoG) fail to reveal the epileptogenic focus for further temporal lobectomy treatment. High-frequency oscillations (HFOs) can be utilized as a biomarker for lateralizing the onset zone in suspected bitemporal epilepsy. Except subjective vision detect the HFOs, objective verification should be performed to raise the accuracy. In the present research, we prospectively studied 10 patients with refractory temporal seizures and who underwent ECoG with wide-band frequency amplifiers (2,048 Hz); all patients had a class I outcome after temporal resection. Pre- and ictal HFOs will be analyzed by wavelet transform (WT) and Granger causality (GC) to objectively verify lateralization of the seizure onset zone (SOZ). WT analysis showed ictal HFOs in 10 patients mainly covered from 80 to 115 Hz (average, 92.59 ± 10.23 Hz), and there was distinct bandpass boundary between pre-ictal HFOs and ictal HFOs. GC analysis showed five patients (2, 4, 5, 6, and 7), no matter the pre-ictal or ictal state, had the highest GC degree in SOZ itself. The remaining patients (1, 3, 8, 9, and 10) had the highest GC degree in SOZ with its adjacent regions in the pre-ictal and ictal stages. GC analysis further confirmed the result of the WT and suggested HFOs are initiated and propagated in the local brain region mainly, afterward, transmitting to adjacent brain regions. These results indicated that the combination of WT and GC analyses significantly contributes to accurate lateralization in patients with suspected bitemporal epilepsy. [ABSTRACT FROM AUTHOR]

Abstract A system of zinc fluoride glasses were synthesized to analyse the sensitization mechanism between doped Ln3+ ions under 808 or 980 nm excitation. Differential scanning calorimetry (DSC) curve and Raman spectra indicate the favourable thermal stability and a low maximum phonon energy of the host. Judd-Ofelt (J-O) theory together with the absorption spectra were utilized to compute the Ω t for predicting radiative features of each sample which coincide with the later measured emission spectra. Broadband emission ranging from 2400 to 3300 nm with a half-width of 361 nm in Er3+/Dy3+ codoped zinc fluoride glasses under 980 nm pumping has been investigated, which may be applicated in mid-infrared fiber amplifier and broadband tunable lasers field. On the other hand, the efficient sensitization effect mechanism between Er3+ and Dy3+ around 3 μm band with an extremely high energy transfer efficiency Ƞ (96.1%) of Er3+:4I 13/2 →Dy:6H 11/2 has been researched under 808 nm excitation. Hence, Er3+ and Dy3+ doped zinc fluoride glasses may be potential optical candidates of great development foreground in the fields of mid-infrared applications. [ABSTRACT FROM AUTHOR]

Even though CMOS-based power amplifiers (PAs) provide reductions in size and cost for wireless local area network (WLAN) applications, their performances must be improved to match those of HBT-based PAs. In this paper, a design methodology for WLAN CMOS PAs is proposed to obtain broadband performances with a compact area using the wafer-level package technology. To achieve a highly linear output power with high efficiency across a 1-GHz bandwidth in a 5G-band PA, a reconfigurable interstage matching network and a broadband compact output transformer are proposed. For applications requiring a high linear transmission power, an integrated CMOS PA in a full transmitter chain must support the operation with external HBT-based PAs. A structure involving a main internal PA with an external PA driver is proposed to support the external PA mode with low-current consumption. The proposed structure does not require additional components or an output port and does not have the performance degradation of the main internal PA. The implemented 2.4G-band/5G-band CMOS PA using 40-nm CMOS technology has an average output power in the ranges of 19.1–19.2/18.6–18.8 dBm in the respective ranges of 2.4–2.5/4.9–5.9 GHz and concurrently complies with the −32-dB error vector magnitude (EVM) requirement. The power-added efficiencies (PAEs) for the 2.4G-band/5G-band CMOS PA with a −32-dB EVM is 12.9%/12.2% at 2.45/5.5 GHz. To the best of the authors’ knowledge, the presented PA exhibits the state-of-the-art minimum variation with high PAE and an output power in the range of 4.9–5.9 GHz compared to the fully integrated WiFi CMOS PAs reported thus far. [ABSTRACT FROM AUTHOR]

A G-band wideband bidirectional transceiver front-end is proposed. Coupled transmission line (CTL) and the staggered inter-stage wideband matching technique are exploited to extend the bandwidth of low noise amplifier (LNA) and power amplifier (PA). The transmit/receive (T/R) switch is realized as a single-pole-double-throw (SPDT) switch to connect the LNA and PA with good matching performance, low insertion loss, and high isolation simultaneously. The proposed G-band bidirectional transceiver front-end is implemented in 40-nm CMOS and occupies $ {870}\,\, {\mu } \textrm {m} {\times } {910}\,\, {\mu } \text{m}$ die area including the pads. The front-end in the transmitter (TX) mode achieves a measured 3-dB bandwidth of 32.8 GHz with a peak gain of 9.6 dB and a simulated saturated output power of 3.0 dBm, while the receiver (RX) mode features a measured 3-dB bandwidth of 34.8 GHz with a maximum gain of 10.5 dB and a simulated minimum noise figure (NF) of 10.8 dB. The implementation of the bidirectional transceiver front-end demonstrates the feasibility to integrate the TX and RX with a single on-chip antenna in G-band. [ABSTRACT FROM AUTHOR]

Energy harvesting for low-power sensing has drawn great attention, but still faces challenges in harnessing broadband random motions. Inspired by the parasitic relationship in plants, a host-parasite vibration harvester is designed to scavenge random low-frequency vibrations by incorporating bi-stability and frequency up-conversion within such a design. A hosting beam is formed in a buckled condition by clamping it at both ends and applying an axial compression load. Two parasitic piezoelectric beams are fixed at the center of the hosting beam and plucked at the free ends by two plectra on the hosting beam, while it oscillates in an inter-well mode. The low-frequency hosting beam oscillation is converted to high-frequency parasitic beam's vibration at resonance due to the plucking effect, allowing the harvester to convert the broadband low-frequency motion into electricity effectively. The electromechanical dynamics are modeled and the design is validated experimentally. The harvester is capable of harnessing low-frequency random vibration (0.0018 g2/Hz @ 5–400 Hz) over a wide bandwidth. More than 1 mJ energy was collected over 100 s under this pseudorandom vibration. [ABSTRACT FROM AUTHOR]

This paper propose an inverted sequential load-modulated balanced amplifier (ISLMBA) for extending the dynamic power range of a power amplifier (PA) over a wide bandwidth. The proposed ISLMBA consists of a control amplifier (CA) and a balanced PA (BPA) pair. A composited impedance inverter is inserted between each BPA transistor and the output coupler. The composited impedance inverter is composed by the intrinsic elements and output matching network (OMN) of the BPA transistor. In this way, the intrinsic elements can be fully absorbed into the impedance inverter over a wide bandwidth. Meanwhile, the load modulation trajectories of the BPA transistors can be optimized over a wide bandwidth by tuning the characteristic impedance of the impedance inverter. The theoretical current, voltage and load-modulation profiles of the ISLMBA are comprehensively analyzed. It is illustrated that the proposed ISLMBA could maintain high efficiency at deep output back-off power level over a wide bandwidth. Moreover, this work designs and fabricates an ISLMBA operating over 1.3–2.55 GHz to verify the proposed PA architecture. The fabricated ISLMBA exhibits a saturation drain efficiency (DE) of 54.5%–73.8% and a saturation output power of 42.9–45.9 dBm. At the same time, the fabricated ISLMBA achieves a 10 dB back-off DE of 42.1%–63.9% over the frequency band of interest. When the fabricated ISLMBA is stimulated by a 20 MHz wideband signal with a peak-to-average power ratio (PAPR) of 10.2 dB at 2.0 GHz, the measured adjacent channel leakage ratios (after predistortion) are −47.7 and −48.8 dBc at the lower and upper bands, respectively. [ABSTRACT FROM AUTHOR]

In this study, Er3+-doped sulfophosphate glasses containing titanium nanoparticles (TiO 2 NPs) with 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05 mol% of silver (Ag) nanoparticles (AgNPs) were synthesized using the melt-quenching technique. The impact of AgNPs on the physical and structural characteristics, optical absorption and emission features, and photocatalytic activity of the glasses were investigated. The density and molar volume of the glasses were determined. Transmission electron microscopy (TEM) was used to study the existence of both AgNPs and TiO 2 NPs in the glass matrix. The absorption spectra of the glasses revealed several bands of absorption in the UV–Vis–NIR region, with peaks at 1534, 977, 795, 650, 544, 520, 487, 450, 406, 378, and 364 nm. The SPR peaks of silver were observed at 553 and 588 nm, while those of TiO 2 NPs were located around 409 and 849 nm. The intensity of emission was found to be enhanced by increasing the concentration of AgNPs. According to the findings of Judd-Ofelt theory, the system containing of 0.04 mol% of AgNPs has also the optimal performance which can be applied to the function of a broadband amplifier by having a high emission cross section of 70.18 × 10−22 cm2. Finally, the photocatalytic performance of the glasses was evaluated by conducting a degradation experiment with methylene blue (MB). The results validated their light-activated self-cleaning properties in the presence of Ag/TiO 2 NPs. • Er3+-sulfophosphate glasses co-embedded with silver and titania nanoparticles were prepared with varying concentrations of silver nanoparticles. • An optimum emission enhancement was observed for the sample containing 0.04 mol% of AgNPs compared to one without. • Spectra of absorption and emission were measured and the J-O theory was applied. • PMZET0.04Ag (70.18 × 10−22 cm2) exhibited the highest emission cross-section associated with the 4F 9/2 → 4I 15/2 transition. [ABSTRACT FROM AUTHOR]

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Abstract The peculiarities of transmission and angular non-reciprocity in magneto-photonic crystals (MPC) are investigated. The problem of light transmission through magneto-photonic crystal is solved by Ambartsumian's modified layer addition method. It is shown that the system under consideration can work as a wide band ideal optical diode for orthogonal circular polarizations and as a narrow band ideal optical diode for orthogonal linear polarizations. The influence of the magnitude of external static magnetic field, its direction, and the angle of incidence on the diode properties are investigated. [ABSTRACT FROM AUTHOR]

Broadband laser ranging (BLR) is an appropriate method to obtain absolute distance in dynamic experiments. In this article, we first analyze the performance limit for BLR and indicate that the measuring range can be hardly increased while keeping the distance or time resolution unchanged. Then, multi-reference BLR is proposed, which can break this limit and greatly increase the measuring range. Its validity is demonstrated by an experiment with an explosively driven aluminum surface flying over 100 mm. This method would improve the capability of BLR. [ABSTRACT FROM AUTHOR]

In this paper, a mixed topology for high efficiency, broadband Doherty power amplifier (DPA) is proposed. The transistor gate biases are set to deep Class-AB for the carrier device and deep Class-C for the peaking device, which enable the DPA to achieve its high efficiency. However, this biasing scheme leads to an inadequate back-off range, which in the past limited applicability. To compensate for this reduced back-off range, a “ $\pi $ -type” harmonic injection network (HIN) is integrated into the DPA thereby allowing the second harmonic to be injected between the two active devices. This achieves waveform engineering, which enhances the output power of the peaking amplifier. However, the use of this HIN leads to a reduction in bandwidth due to a mismatch at the fundamental frequency. A bandwidth compensation technique is then proposed, thereby reducing the peaking device drain impedance variation. This mitigates the reduction in bandwidth as a result of the HIN. A high-efficiency DPA is prototyped based on two identical 10-W gallium nitride HEMTs. Measurement results show that a drain efficiency of greater than 60% is achieved at 5.3–6-dB output back-off power from 1.4 to 2.1 GHz. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of a bidirectional distributed amplifier (BDDA) in a 0.18- $\boldsymbol \mu \text{m}$ CMOS process. The performance of the BDDA is theoretically analyzed, and the optimum number of gain stages ($n_{\text {opt}}$), maximum achievable power gain ($G_{P}$), and circuit bandwidth are formulated. In addition, a new formula for proper choice of the number of DA stages (i.e., $n$) is offered where dc-power consumption of the circuit ($P_{\text {dc}}$) is also considered. This formula optimizes $G_{P}/P_{\text {dc}}$ , and it is preferred over the conventional $n_{\text {opt}}$ formula. To validate the theoretical analyses, a 2–12-GHz BDDA with high output 1-dB compression point of +16 dBm and small-signal gain of 10 dB is fabricated. The BDDA chip occupies 1.89-mm2 die area, and its average measured noise figure and $P_{\text {dc}}$ are 6.8 dB and 0.38 W in the high-power mode and 6.5 dB and 0.13 W in the low-power mode, respectively. [ABSTRACT FROM AUTHOR]