共查询到20条相似文献,搜索用时 31 毫秒
1.
This article designed a five‐order narrow‐band tunable superconducting filter. The superconducting microstrip circuit was loaded by varactors diode. The center frequency of the tunable can be tuned through the changing of the bias voltage added in the varactors diode. The whole device has a parallel coupling structure and the filter circuit was fabricated by DyBa2Cu3O7 superconducting film with 0.5 mm thickness and 2 in. LaAlO3 as the substrate. The frequency can be continuously adjusted from 235 MHz to 250 MHz. The insertion loss of the filter was in the range of 2.51 dB to 9.64 dB. The bandwidth of the tunable filter was in the range of 0.5 MHz to 0.9 MHz. The out‐of‐band rejection was better than 70 dB. The measured results are in good agreement with the simulated ones. 相似文献
2.
An angular‐stable multi‐layer reconfigurable frequency selective surface (FSS) based on varactor with wide tuning range is proposed in this article. The working principle of the FSS is analyzed by the equivalent circuit model (ECM). By tuning the DC bias voltage applied to the varactors loaded on the top and bottom layers, the pass band of the FSS can be located in the C, X, and Ku band respectively with a wide reconfigurable range. In addition, due to the introduction of the miniaturized structure and the four metal vias in Z‐direction, the FSS provides good angular stability under TE and TM polarization. Finally, the fabrication and experiment are provided to verify the validity of the reconfigurable FSS. 相似文献
3.
Lachezar Komitov 《Journal of the Society for Information Display》2003,11(3):437-441
Abstract— Fast in‐plane switching of the optic axis was realized in liquid‐crystal displays (LCDs) based on the concept of Electrically Commanded Surfaces (ECS). According to this concept, the liquid‐crystal layer in such a display is aligned by means of thin ferroelectric liquid‐crystal‐polymer (FLCP) film deposited onto the inner side of the display substrates. An electric field, applied normal to the substrates, switches the molecules of the ferroelectric film, representing the commanded surface that, via elastic forces, further transfers to the liquid‐crystal layer. The concept of electrically commanded surfaces opens the door to a new generation of advanced LCDs exhibiting extraordinary performance such as fast in‐plane switching. 相似文献
4.
A compact self‐matched negative group delay circuit (NGDC) with tunable center frequency and tunable group delay (GD) is proposed. Two varactors and a variable resistor are utilized to implement the tunability of the center frequency and GD of the proposed NGDC. To verify the design concept, a tunable NGDC is designed and fabricated. The measured center frequency is tuned from 0.8 to 1.3 GHz and the measured NGD time is tuned from ?1 to ?10 ns. The insertion loss varies from 16.0 to 34.5 dB. In the process of tuning the center frequency and NGD time, the return losses keep better than 30 dB. 相似文献
5.
Compact reconfigurable rat‐race coupler with tunable frequency and tunable power dividing ratio
下载免费PDF全文
![点击此处可从《国际射频与微波计算机辅助工程杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A compact reconfigurable rat‐race coupler with tunable frequency and tunable power dividing ratio is proposed for the first time. Varactors and two single control voltages are used to obtain both the tunable frequency and the tunable power dividing ratio in this article. The structure of the rat‐race coupler involves 50 Ω parallel‐strip lines only and a phase inverter is used for size reduction. Theoretical equations for the relationship among S‐parameters and the capacitance of varactors are derived. The graphic method is used to choose capacitance for the desired operation frequency and the desired power dividing ratio. For demonstration, a prototype is designed and fabricated. The measured results show that the rat‐race coupler's frequency and the power dividing ratio can be effectively tuned in 0.69 GHz ~ 0.81 GHz and 3 dB ~ 14 dB, respectively with isolation better than 20 dB, phase difference less than 7°and return loss better than 20 dB. The theoretical simulation, electromagnetic simulation, and measured results show good agreement in this design. 相似文献
6.
Comparative study of a‐IGZO TFTs with direct current and radio frequency sputtered channel layers
下载免费PDF全文
![点击此处可从《Journal of the Society for Information Display》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wei Deng Xiang Xiao Xin He Chia‐Yu Lee Shengdong Zhang 《Journal of the Society for Information Display》2015,23(7):306-312
In this work, a comparative study of electrical properties and gate‐bias stress stability between direct current (DC)‐sputtered and radio frequency (RF)‐sputtered amorphous indium–gallium–zinc oxide thin film transistors (a‐IGZO TFTs) is conducted. The RF‐sputtered a‐IGZO TFTs show higher field‐effect mobility and steeper sub‐threshold slope. The DC‐sputtered ones show a better uniformity of threshold voltage, enhanced stability under both positive bias stress and negative bias illumination stress. The X‐ray photoelectron spectroscopy characterization of the a‐IGZO films reveals that the concentration of oxygen vacancies and electron density in the RF‐sputtered a‐IGZO film is higher than that in the DC‐sputtered one, which probably accounts for the differences of electrical properties between the RF‐sputtered and DC‐sputtered a‐IGZO TFTs. 相似文献
7.
This article introduces a novel two‐section frequency‐tunable branch line coupler, which is realized by inserting a narrow band frequency‐tunable phase inverter into a wideband two‐section branch line coupler's middle branch line. Such frequency‐tunable method is different from the conventional one. Furthermore, in this bias feeding design, there are only one control voltage, two varactors, two resistors, and two capacitors are utilized. The measured results show that the operation frequency of the branch line coupler can be tuned from 0.73 to 1.33 GHz, and the return loss is >20 dB, the isolation >20 dB, the amplitude imbalances <1 dB, and the phase imbalances is <2°. Through the comparison, the measured results basically conform to the simulated results in this design. 相似文献
8.
Masahiro Kawasaki Shuji Imazeki Shoichi Hirota Tadashi Arai Takeo Shiba Masahiko Ando Yutaka Natsume Takashi Minakata Sei Uemura Toshihide Kamata 《Journal of the Society for Information Display》2008,16(1):161-167
Abstract— A solution‐processed organic thin‐film‐transistor array to drive a 5‐in.‐diagonal liquid‐crystal display has been fabricated, where semiconductor films, a gate dielectric film, and passivation films have all been formed using solution processes. A field‐effect mobility of 1.6 cm2/V‐sec, which is among the highest for solution‐processed organic thin‐film transistors ever reported, was obtained. This result is due to semiconductor material with large‐grain‐sized pentacene crystals formed from a solution and adoption of three‐layered passivation films that minimize the performance degradation of organic thin‐film transistors. 相似文献
9.
Jeoung‐Yeon Hwang Chang‐Joon Park Dae‐Shik Seo Youn‐Hak Jeong Kyung‐Chan Kim Han‐Jin Ahn Hong‐Koo Baik 《Journal of the Society for Information Display》2005,13(3):227-231
Abstract— A fringe‐field‐switching (FFS) mode cell having LC alignment has been developed by using a non‐rubbing method, a ion‐beam‐alignment method on a‐C:H thin film, to analyze the electro‐optical characteristics of this cell. The suitable inorganic thin film for FFS‐LCDs and the alignment capabilities of nematic liquid crystal (NLC) have been studied. An excellent voltage‐transmittance (V‐T) and response‐time curve for the ion‐beam‐aligned FFS‐LCDs were observed using oblique ion‐beam exposure on DLC thin films. 相似文献
10.
In this article, a large‐signal modeling approach based on the combination of equivalent circuit and neuro‐space mapping modeling techniques is proposed for MOSFET. In order to account for the dispersion effects, two neuro‐space (S) mapping based models are used to model the drain current at DC and RF conditions, respectively. Corresponding training process in our approach is also presented. Good agreement is obtained between the model and data of the DC, S parameter, and harmonic performance for a 0.13 μm channel length, 5 μm channel width per finger and 20 fingers MOSFET over a wide range of bias points, demonstrating the proposed model is valid for DC, small‐signal and nonlinear operation. Comparison of DC, S‐parameter, and harmonic performance between proposed model and empirical model further reveals the better accuracy of the proposed model. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011. 相似文献
11.
Xiao‐Lan Tang Emmanuel Pistono Philippe Ferrari Jean‐Michel Fournier 《国际射频与微波计算机辅助工程杂志》2016,26(2):99-109
A three‐stage 60‐GHz power amplifier (PA) has been implemented in a 65 nm Complementary Metal Oxide Semiconductor (CMOS) technology. High‐quality‐factor slow‐wave coplanar waveguides (S‐CPW) were used for input, output and inter‐stage matching networks to improve the performance. Being biased for Class‐A operation, the PA exhibits a measured power gain G of 18.3 dB at the working frequency, with a 3‐dB bandwidth of 8.5 GHz. The measured 1‐dB output compression point (OCP1dB) and the maximum saturated output power Psat are 12 dBm and 14.2 dBm, respectively, with a DC power consumption of 156 mW under 1.2 V voltage supply. The measured peak power added efficiency PAE is 16%. The die area is 0.52 mm2 (875 × 600 μm2) including all the pads, whereas the effective area is only 0.24 mm2. In addition, the performance improvement of the PA in terms of G, OCP1dB, Psat, PAE and the figure of merit using S‐CPW instead of thin film microstrip have been demonstrated. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:99–109, 2016. 相似文献
12.
A design method for flicker‐free liquid crystal display panels based on indium‐gallium‐zinc‐oxide thin‐film transistors
下载免费PDF全文
![点击此处可从《Journal of the Society for Information Display》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper proposes a design method to reduce the flicker of liquid crystal display panels based on indium‐gallium‐zinc‐oxide (IGZO) thin‐film transistors (TFTs). The proposed design method employs a human factor model to convert the flicker measured at low frame frequency (F FRAME) to a modification value of the measured flicker (MVMF ) having a frequency sensitivity of flicker, which can distinguish between no blinking and weak blinking. To investigate the causes and characteristics of flicker, the frequency component and increase factor of flicker are analyzed using the checkerboard and solid images. The increase factor in flicker is examined using IGZO TFTs with different antenna ratios (AR s) that cause the variation in threshold voltage of IGZO TFT. To verify the proposed design method, two test panels are implemented with asymmetric and symmetric AR s. The MVMF s of the 15 Hz component at a low F FRAME of 30 Hz show that the solid image with a symmetric AR has an MVMF of ?62.9 dB, which is improved by 24.3 dB compared to that with an asymmetric AR . Therefore, the proposed method is applicable for a flicker‐free liquid crystal display panels at a low F FRAME. 相似文献
13.
In this paper, a balanced dual‐band bandpass filter (BPF) with high selectivity and low insertion loss performance is presented by employing stub loaded resonators (SLRs) and stepped impedance resonators (SIRs) into balanced microstrip‐slotline (MS) transition structures. The balanced MS transition structures can achieve a wideband common‐mode (CM) suppression which is independent of the differential‐mode (DM) response, significantly simplifying the design procedure. Six varactors are loaded into the resonators to achieve the electrical reconfiguration. The proposed balanced dual‐band BPF can realize quasi‐independently tunable center frequencies and bandwidths. A tuning center frequency from 2.48 to 2.85 GHz and a fractional bandwidth (20.16%‐7.02%) with more than 15 dB return loss and less than 2.36 dB insertion loss are achieved in the first passband. The second passband can realize a tuning center frequency from 3.6 to 3.95 GHz with more than 12 dB return loss and less than 2.38 dB insertion loss. A good agreement between the simulated and measured results is observed. 相似文献
14.
Pradipta K. Nayak Jongsu Jang Changhee Lee Yongtaek Hong 《Journal of the Society for Information Display》2010,18(8):552-557
Abstract— The effects of lithium (Li) doping concentration and gate dielectrics on the performance of solution‐processed zinc‐oxide (ZnO) thin‐film transistors (TFTs) has been investigated. ZnO films with strong c‐axis orientation and lower background conductivity was obtained with 15 at.% of Li. Different crystallization behavior of ZnO was observed in the case of various dielectric surfaces. The 15‐at.% Li‐doped ZnO films (thickness ~20 nm) prepared on SiO2 and SiNx were found to be present in crystalline form, whereas the film prepared on aluminum titanium oxide (ATO) was found to be amorphous. A field‐effect mobility of 1.81 cm2/V‐sec and an Ion/Ioff ratio of 2 × 106 were obtained for the 15‐at.% Li‐doped ZnO TFTs with a bilayer gate dielectric of SiO2 and SiNx. The comparison of dielectric studies showed that the performance of TFTs prepared on SiNx and ATO are higher than that of the TFTs prepared on SiO2. 相似文献
15.
This review article provides an extensive literature survey on the research progress of dielectric resonator antenna (DRA) at millimeter‐wave frequency band that includes concepts of DRAs, their empirical formulae and design methodologies for different shaped DRAs at 60 GHz frequency band. The different shaped DRAs such as cylindrical, rectangular, hexagonal, and octagonal at 60 GHz are designed, simulated and analyzed using CST microwave studio solver. The ?10 dB impedance bandwidth of cylindrical, rectangular, hexagonal, and octagonal DRAs are 52.7 to 62.8 GHz, 57 to 62.2 GHz, 55.8 to 64.2 GHz, and 54.2 to 63.5 GHz, respectively. The idea behind getting broad impedance bandwidth is due to use of double‐layer substrate with different permittivity (εr1 = 4 and εr2 = 11.9). Empirical formulae are deduced for hexagonal and octagonal DRA, by studying the analogy of dielectric resonator geometry. Consequently, the mode of different shaped DRAs, that is, HEM111 and TE111 are investigated by the electric field and magnetic field distribution. With these analysis, a comprehensive research review over the period of the last two decades is carried for investigating various techniques, targeted to realized gain, circular polarization, and impedance bandwidth. Along with these analysis the state‐of‐the‐art at different shaped DRAs at mm‐wave frequency band are also reported. 相似文献
16.
This article presents the design of a miniaturized dual‐band antenna for long‐term evolution (LTE) application is presented. In the basic antenna design, split ring resonator was loaded in the radiating plane of the patch and frequency of resonance was further modified with the help of E‐shaped stub. The antenna has been fabricated using FR‐4 substrate and the measured dual bands at 2.11 and 2.665 GHz are found in a close match with the simulated data. By placing a thin dielectric resonator of permittivity ε r = 10.2 and thickness of 1.27 mm, two closely spaced narrow bands are obtained at 2.217 and 2.28 GHz. A novel metamaterial unit‐cell having near‐zero refractive index is designed and mounted above the dielectric resonator. This stack configuration generates triple narrow frequency band in the LTE 2 GHz spectrum range. The overall size of the proposed antenna is 20 × 25 mm2. 相似文献
17.
The wideband bandpass filtering branch‐line balun with high isolation is presented in this paper. The proposed balun can be designed for wideband performances by choosing a proper characteristics impedance of input vertical transmission line and odd‐mode impedance of parallel‐coupled lines. The proposed balun was designed at a center frequency (f0) of 3.5 GHz for validation. The measured results are in good agreement with the simulations. The measured power divisions are ?3.31 dB and ?3.24 dB at f0 and ?3 ± 0.17 dB within the bandwidth of 0.95 GHz (3 GHz to 3.95 GHz). The input return loss of 24.09 is measured at f0 and higher than 20 dB over the same bandwidth. Moreover, the measured output losses are better than 11 dB within a wide bandwidth. The isolation between output ports is 20.32 dB at f0 and higher than 13.2 dB for a broad bandwidth from 1 GHz to 10 GHz. The phase difference and magnitude imbalance between two output ports are 180° ± 4.5° and ± 0.95 dB, respectively, for the bandwidth of 0.95 GHz. 相似文献
18.
Yong‐Hoon Kim Won‐Keun Kim Jeong‐In Han Dae‐Gyu Moon 《Journal of the Society for Information Display》2007,15(12):1105-1108
Abstract— Low‐temperature‐polysilicon thin‐film transistors (LTPS TFTs) were fabricated on polymer substrates using sputtered amorphous‐Si (a‐Si) films and excimer‐laser crystallization. The in‐film argon concentration of a‐Si films was minimized as low as 1.6% by using an argon/helium gas mixture as the sputtering gas. By employing XeCl excimer‐laser crystallization, poly‐Si films were successfully fabricated on polymer substrates with an average grain size of 400 nm. With a four‐mask process, a poly‐Si TFT was fabricated with a fully self‐aligned top‐gate structure, and the pMOS TFT device showed a field‐effect mobility of 63.6 cm2/V‐sec, ON/OFF ratio of 105, and threshold voltage of ?1.5 V. 相似文献
19.
The accurate physical parameters of the semiconductor devices are critical to the physics‐based circuit simulation, which solves the carrier transport equations to model the semiconductor devices. However, the conventional method extracts physical parameters from low‐frequency measurements such as the DC I‐V curve, which cannot work at high frequencies. To overcome this problem, we propose a physical parameter extraction method of the PIN diode working well from DC to microwave frequencies. Specifically, because the transit‐time effects are dependent on the working frequencies and input power levels, the operation modes of the PIN diode can be divided into three cases from DC to microwave frequencies; therefore, the proposed method extracts the parameters from three measured curves, including the DC I‐V curve, a small‐signal, and a large‐signal voltage waveform both at a microwave frequency. Experiments of a PIN diode SMP1330 circuit show that the error of the conventional method is about 45% at frequencies above 300 MHz, but the maximum error of the proposed method is only 9.5% from DC to 2 GHz. Moreover, the conventional method is unable to characterize the conductance modulation phenomenon, which leads to unexpected signal reflections in PIN limiter circuits and the missing of information in radio transceivers. 相似文献
20.
Jehuda Greener Herong Lei James Elman Janglin Chen 《Journal of the Society for Information Display》2005,13(10):835-839
Abstract— Many of the films used in polarizer assemblies in LCDs (e.g., triacetyl cellulose or TAC) are produced by a solvent‐casting process, which is known to impart optical anisotropy to the film expressed as finite out‐of‐plane birefringence. This feature of the film could have a significant impact on the optical performance of the display and it needs to be accounted for in any compensation scheme for the LC cell. This paper reviews the origin of this optical anisotropy, and it presents a viscoelastic model that links this property to the solvent‐casting process and to some key material parameters. The model results are compared with experimental data generated for polystyrene films cast from toluene, and generally good agreement is demonstrated. 相似文献