In this brief, a low-loss self-packaged Ka-band LTCC filter is proposed based on an artificial multi-mode substrate integrated waveguide (SIW) resonator. Two ridges and two metal strips are tightly ...integrated in one SIW cavity to form the artificial quad-mode resonator. Due to the shielding of the SIW cavity, the resonator realizes a high Q factor, which contributes to an extremely low loss of the Ka-band filter. A fast design method for the bandpass filter based on an artificial multi-mode resonator is introduced. A simple approach to accurately extract all external Q factors for multiple resonant modes at the same time is also discussed. A pair of transmission zeros are generated to improve the filter skirt selectivity. For verification, a filter operating at 28 GHz is fabricated on the LTCC process. The measured result shows a low insertion loss of 0.8 dB, which is attracted in millimeter-wave applications.
This article presents a high-efficiency dual-band filtering Doherty power amplifier (DPA) using multi-function circuits for simplifying the structure. A dual-band filtering power combiner also plays ...the role of real-to-real impedance matching, in which one resonator is shared by both the power combing and filtering circuits. Thus, only one extra resonator is needed for the power combiner to provide second-order dual-band filtering responses, which contributes to high efficiency of the DPA. Transmission zeros are generated between the two passbands, realizing a sharp roll-off rate and greatly enhancing the isolation between the two passbands. Meanwhile, an impedance control network is designed to simultaneously suppress the harmonics and transform the optimized complex impedance desired by the transistor to a real one. In this way, the output matching network and extra filter in conventional design are realized by the filtering power combiner and impedance control network in the proposed design, resulting in a simpler structure. A dual-band DPA operating at 2.14 and 2.6 GHz is implemented with the measured peak efficiencies of 64.4% and 69% at the output power of 43.25 and 43.3 dBm, respectively. The 6-dB back-off efficiencies are 50% and 57% at the two passbands. Under 20-MHz long term evolution (LTE) modulated signals with a peak-to-average power ratio (PAPR) of 7.5 dB, the DPA after digital predistortion (DPD) is measured with an adjacent channel leakage ratio (ACLR) of better than −45.2 dBc and the efficiencies of 51.6% and 54.3% at interested bands. The peak efficiency under the excitation of the concurrent modulated signal is 48.6%.
Catalytic alkene difunctionalization via Si−H and C−H activations represents an ideal atom‐ and step‐economic pathway for quick assembly of molecular complexity. We herein developed a ...visible‐light‐promoted metal‐free difunctionalization of alkenes using abundant CO2 and readily available Si−H and C(sp3)−H bonds as feedstocks. Through the merger of photoredox and hydrogen‐atom‐transfer catalysis, a variety of value‐added compounds, such as β‐silacarboxylic acids and acids bearing a γ‐heteroatom (e.g., N, O, S) could be directly accessed from simple alkenes in a redox‐neutral fashion.
Photocarboxylation: Visible‐light‐promoted metal‐free difunctionalization of alkenes using CO2 and readily available Si−H and C(sp3)−H reagents has been realized by the merging of photoredox and hydrogen‐atom‐transfer catalysis. A variety of valuable compounds, such as β‐silacarboxylic acids and acids bearing a γ‐heteroatom (e.g., N, O, S) can be directly accessed from simple alkenes in a redox‐neutral fashion.
In this paper, a low-temperature co-fired ceramic (LTCC) diplexer is presented with compact size and high isolation. By using the common stub-loaded resonator shared by two channel filters, combining ...and matching networks are eliminated and only three resonators are used to design the two second-order channel filters, resulting in simple structure and miniaturized size. A novel transmission path is utilized to not only realize the higher channel filter but also prevent the signal at the lower frequency band. And a specific coupling region is selected to simultaneously realize the coupling strength required by lower channel filter and a transmission zero at higher-band frequency. In this way, each channel filter can generate a transmission zero at the passband frequency of the other channel filter, resulting in high isolation. Moreover, the bandwidths and center frequencies of the two channel filters can be individually controlled due to the design flexibility of the multilayer LTCC structure. For demonstration, a diplexer operating at 3.5 and 5.5 GHz is fabricated. The core circuit has the compact size of 1.9 mm × 1.7 mm × 2 mm or 0.054 λ g ×0.048λ g ×0.057 λ g . Within the 3-dB passbands of the lower and higher channel filters, the measured isolation levels are better than 40 and 45 dB, respectively.
Summary
In this paper, we present a novel parametric iterative learning control (ILC) algorithm to deal with trajectory tracking problems for a class of nonlinear autonomous agents that are subject ...to actuator faults. Unlike most of the ILC literature, the desired trajectories in this work can be iteration dependent, and the initial position of the agent in each iteration can be random. Both parametric and nonparametric system unknowns and uncertainties, in particular the control input gain functions that are not fully known, are considered. A new type of universal barrier functions is proposed to guarantee the satisfaction of asymmetric constraint requirements, feasibility of the controller, and prescribed tracking performance. We show that under the proposed algorithm, the distance and angle tracking errors can uniformly converge to an arbitrarily small positive number and zero, respectively, over the iteration domain, beyond a small user‐prescribed initial time interval in each iteration. A numerical simulation is presented in the end to demonstrate the efficacy of the proposed algorithm.
In this letter, a miniaturized bandpass filter chip is designed and implemented on high-resistivity-silicon (HRS) integrated passive device (IPD) technology. The filter is designed into a three-path ...topology, which can generate multiple transmission zeros to achieve a high roll-off rate at the passband edge and good rejection in a very wide stopband. For validation, the filter chip operating at 5G N77 frequency band is fabricated with a compact size of <inline-formula> <tex-math notation="LaTeX">1.1\times0.7 </tex-math></inline-formula> mm2 on IPD technology. Measured results show an in-band insertion loss of smaller than 1.7 dB and a wide stopband from 5.39 to 31.5 GHz.
The formation of Mst7 homodimers involves the thioredoxins and is important for Pmk1 activation 6. Besides its intramolecular self-inhibitory binding, Mst11 also interacts with Ras proteins via the ...Ras-association domain for Pmk1 activation 7,8. The Cochliobolus sativus Cshog1 mutant is normal in root infection but significantly reduced in virulence on barley leaves 15. ...the function of this MAPK pathway in pathogenesis may be not only species-specific but also tissue-specific. Besides its conserved role in osmoregulation, this pathway has species-specific functions in pathogenesis, vegetative growth, fungicide sensitivity, sexual and asexual development, and responses to oxidative, cell wall, and other stresses in different plant pathogenic fungi. Deletion of MST50 also affects Osm1 activation in response to hyperosmotic stress, and Hik1 interacts with Mst50 26. Because the cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) pathway also regulates various developmental and infection processes, cross-talking between cyclic adenosine monophosphate (cAMP) signaling and MAPK cascades must occur and likely involve different mechanisms in plant pathogenic fungi 1,2,27.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A novel filtering power divider with wide stopband is presented in this letter. It utilizes four coupled quarter-wavelength resonators to obtain dual functions. Discriminating coupling is applied to ...the input and output feed lines and resonators, which not only to provide suitable coupling strength but also to suppress 3f 0 and 5f 0 (f 0 is the operating frequency). A resistor is connected at the two open-ends of the input feed line to obtain high isolation. Transmission zeros are generated near the passband edges, resulting in high selectivity. For demonstration, a power divider with filtering function as well as wide stopband is implemented. Good agreement between the prediction and measurement validates the proposed method.
This paper presents a broadband Doherty power amplifier (DPA) using quarter-wavelength (<inline-formula> <tex-math notation="LaTeX">\lambda </tex-math></inline-formula>/4) transmission lines with ...negative characteristic impedance. In conventional DPA designs, the load modulation network is frequency-dependent, leading to bandwidth limitation at the back-off power region. In this design, by integrating two <inline-formula> <tex-math notation="LaTeX">\lambda </tex-math></inline-formula>/4 transmission lines with negative characteristic impedance into the main and auxiliary branches, the impedance at the back-off power can be manipulated to maintain high efficiency at back-off power over a wide frequency range. Thus, the operational bandwidth is extended. In circuit realization, the two negative characteristic impedance <inline-formula> <tex-math notation="LaTeX">\lambda </tex-math></inline-formula>/4 transmission lines are replaced by paralleled negative LC components. Then, the negative capacitor is combined into the <inline-formula> <tex-math notation="LaTeX">\pi </tex-math></inline-formula>-shaped impedance matching network, while the negative inductor is eliminated by introducing Norton transformation. For verification, a broadband DPA with a fractional bandwidth of 108.6% from 0.8 to 2.7 GHz is implemented. The measured saturated output power is 41.8-44 dBm. The saturated and 6-dB back-off power drain efficiencies are 47.6%-84.4% and 39.5%- 52%, respectively. A 20-MHz LTE modulated signal with peak-to- average power ratio (PAPR) of 7.5 dB is also applied to measure the fabricated DPA. After digital predistortion, the adjacent channel leakage ratio (ACLR) better than −45.35 dBc is achieved, and the measured average efficiency is higher than 40% within the operating band.
This paper presents a Doherty power amplifier (DPA) with reduced size and wide bandwidth by using a simplified output matching topology. In broadband DPA designs, post-matching networks are usually ...added after the combing node, which usually occupy large circuit sizes. However, in this design, the post-matching network is not used. Instead, two ideal transformers and specific output matching components are employed at carrier and peaking branches. Then, by rearranging the output matching components in the two branches, Norton transformation can be used and the ideal transformers can be eliminated. In this way, the impedance at the combining node is directly matched to a 50-<inline-formula> <tex-math notation="LaTeX">\Omega </tex-math></inline-formula> load without using a post-matching network, resulting in both compact size and wide bandwidth. For verification, a broadband DPA prototype with a very simple structure is implemented. The fabricated circuit shows a compact size. A wide bandwidth from 1.3 to 2.8 GHz (73%) is achieved with a saturated output power of 41.4-44.6 dBm. The drain efficiencies at saturation and 6-dB back-off power level are 60.1-79.1% and 41.8-61%, respectively, which are comparable to those of state-of-the-art designs.
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