Microstrip-Slot Coupler Design-Part II: Practical Design Aspects

Practical aspects of designing microstrip-slot couplers on an Al/sub 2/O/sub 3/ ceramic substrate (epsilon/sub r/ = 9.8) are treated in supplementation of the theoretical analysis of the coupler presented in Part I. Comparison with implemented couplers yields rules for specification of the reference planes at the ends of the coupling section, for the appropriate choice of definition for the slot-line characteristic impedance. Design data of the standard versions of the microstrip transmission line, the slot line are shown to be adequate for the microstrip-slot coupler. Computed S -parameter curves plotted for various 3-dB couplers yield information on realizable transmission characteristics.     

工作频率比可控的微带-缝隙双频耦合器设计北大核心CSCD

针对单一工作频段的微带-缝隙耦合器,提出了一种级联两段微带-槽线传输线的微带-缝隙双频耦合器。通过槽线补偿线对耦合器奇模相速度进行补偿,使奇模相速度近似于偶模相速度,从而改善器件的工作带宽。为指导设计,将对称四端口网络奇偶模的分析拓展到微带-缝隙双频耦合器的设计中,并给出了详细的计算公式。与其他双频定向耦合器相比,该结构实现了工作频率可控的双频等分设计,且每个工作频段带宽更宽。为验证设计方法,设计了一个工作频率在2.4 GHz/5.8 GHz的微带-缝隙双频耦合器。实测结果与仿真数据相吻合,证明了该设计方法的有效性。     

Optimum Design of Wideband Compensated and Uncompensated Marchand Baluns With Step Transformers

This paper presents a design approach for wideband compensated and uncompensated Marchand baluns with stepped-impedance transformers. In order to obtain an equal-ripple bandpass response, conventional Chebyshev polynomials are modified to compensate the effect of the transfer function's dc poles. Unlike the available microwave filter design approaches, which usually require redundant elements, this approach leads to an optimum design by using the minimum number of equal length transmission line elements. Based on this design approach, both compensated and uncompensated Marchand baluns are studied. It is found that increasing difficulty arises when implementing a large bandwidth balun using the widely adopted compensated balun structure. Hence, the uncompensated balun structure becomes a better choice. To validate the proposed design approach, an uncompensated balun is designed on a standard two-sided printed circuit board. The measured results indicate that a return loss greater than 20 dB can be observed from 1 to 7.5 GHz. The phase imbalance is less than 4° and the amplitude is less than 0.5 dB from dc to 7.2 GHz.      

The Comparison Between the Graded Photonic Crystal Coupler and Various Couplers

The coupling between a dielectric waveguide and a photonic crystal waveguide is studied theoretically and experimentally. The coupling methods studied in this work include graded photonic crystal coupler, photonic crystal taper, waveguide taper, and parabolic mirror coupler. The properties of each coupler are discussed and compared.      

Wide-Band Single-Side Band Subharmonic Mixer Constructed With Re-Entrant Couplers and Lumped-Element Coupler

This work presents a new configuration of single-side band (SSB) harmonically pumped mixer implemented by using two kinds of wide-band quadrature couplers to achieve the characteristics of wide operation bandwidth, high side band suppression and compact circuit size. A new type of 3 dB re-entrant microstrip coupler, which is easy to integrate with the surface-mounted devices, is adopted to achieve the required quadrature phase shifts of the radio frequency (RF) and local oscillation signals. The lump-element type of intermediate frequency coupler is not only able to have broadband characteristics and compact circuit size, but also provide the low-pass filtering function to eliminate the low-pass filter of the mixer in the conventional design. An experimental prototype of the proposed SSB mixer was manufactured. The measured conversion losses of the prototype, which includes the losses caused by couplers, are lower than 13 dB. It also shows greater than 20 dB side-band suppression over the RF frequency range of 2.2 to 2.85 GHz and the measured side-band suppression at some RF frequencies are up to 45 dB. The size of the S-band prototype fabricated on FR4 PCB is only about $40times 45 {rm mm}^{2}$.      

Design of Compensated Coupled-Stripline 3-dB Directional Couplers, Phase Shifters, and Magic-T's—Part I: Single-Section Coupled-Line Circuits

The problem of discontinuities in coupled-stripline 3-dB directional couplers, phase shifters, and magic-T's, regarding the connections of coupled and terminating signal lines, has been comprehensively investigated for the first time. The proposed equivalent circuit of these discontinuities, of which parameters can be computed in a process of fitting curves of the circuit and electromagnetic analyses, has been used for accurate modeling of coupled-stripline circuits. It has been shown that parasitic reactances, which result from connections of signal and coupled lines, severely deteriorate the return losses and the isolation of such circuits, and that these discontinuity effects can be substantially reduced by connecting compensating shunt capacitances to both coupled and signal lines. Results of measurements carried out for various designed and manufactured coupled-line circuits are most promising and prove the efficiency of the proposed compensation technique. This paper describes the technique of capacitive compensation of discontinuity effects in single-section coupled-line circuits     

Design of Compensated Coupled-Stripline 3-dB Directional Couplers, Phase Shifters, and Magic-T's—Part II: Broadband Coupled-Line Circuits

The problem of discontinuities in broadband multisection coupled-stripline 3-dB directional couplers, phase shifters, high-pass tapered-line 3-dB directional couplers, and magic-T's, regarding the connections of coupled and terminating signal lines, is comprehensively investigated in this paper for the first time. The equivalent circuit of these discontinuities proposed in Part I has been used for accurate modeling of the broadband multisection and ultra-broadband high-pass coupled-stripline circuits. It has been shown that parasitic reactances, which result from the connections of signal and coupled lines, severely deteriorate the return losses and the isolation of such circuits and also—in case of tapered-line directional couplers—the coupling responses. Moreover, it has been proven theoretically and experimentally that these discontinuity effects can be substantially reduced by introducing compensating shunt capacitances in a number of cross sections of coupled and signal lines. Results of measurements carried out for various designed and manufactured coupled-line circuits have been very promising and have proven the efficiency of the proposed broadband compensation technique. The theoretical and measured data are given for the following coupled-stripline circuits: a decade-bandwidth asymmetric three-section 3-dB directional coupler, a decade-bandwidth three-section phase-shifter compensator, and a high-pass asymmetric tapered-line 3-dB coupler.     

Analysis and Synthesis of Waveguide Multiaperture Directional Couplers

A precise method of analysis of multiaperture waveguide directional couplers has been developed and used to investigate the performance of couplers designed both by conventional theories and by a new synthesis technique. The analysis is based on the equivalent four-port network of the coupler, the apertures being represented by lumped reactances in series and/or shunt with dispersive transmission lines, representing the waveguides. The effects of finite aperture dimensions and common wall thickness are taken into account. Many couplers designed on the usual basis of a first-order loose-coupling approximation have good directivity, even for tight (3 dB) coupling, but previous theories do not give the predicted directivity and are often far from optimum in design. A new synthesis technique based on the distributed low-pass prototype filter has been devised, and shown to give results close to the predicted performance. It has led to the construction of compact multiaperture directional couplers having directivity greater than 43 dB over complete waveguide operating bands.     

The Design and Performance of Three-Line Microstrip Couplers

An analysis is presented of microstrip-coupler circuits consisting of three parallel lines. The analysis is based on the existence of three mode impedances. Design equations describing the performance of this type of coupler are derived and allow the prediction of its matching and transmission properties. Numerical results using finite difference methods are presented for a three-line microstrip coupler made on an alumina substrate (k = 9.8). Experimental results for a 10-dB tbree-line coupler with a center frequency of 4 GHz show that its performance can be reasonably well predicted by the developed theory.     

光电耦合器封装及相关失效机理

与一般的半导体器件相比,光电耦合器的工作原理、结构和封装设计独具特色。光耦的失效机理除与单独的LED、三极管相同外,还有它独有的失效机理。在简单介绍光耦的工作原理与封装结构的基础上,重点分析了几种与光耦封装有关的失效机理:导光胶或反射胶工艺控制不佳导致胶开裂、起皮;光耦内部材料间热膨胀系数不匹配,内部电连接开路;内部沾污产生腐蚀;塑料和内部有机胶吸潮发生"爆米花效应";外部电路异常导致光耦失效。并针对各种失效机理提出了改进措施。     

Design and Characterization of Dielectric-Loaded Plasmonic Directional Couplers

Ultracompact directional couplers (DCs) based on dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) are analyzed using the effective index method (EIM), with the coupling, both in the parallel interaction region and in- and out-coupling regions, being taken into account. Near-field characterization of fabricated DCs performed with a scanning near-field optical microscope verifies the applicability of the EIM in the analysis and design of DLSPPW-based wavelength-selective DCs. The design approach applicable to a large variety of integrated optical waveguides is developed, enabling the realization of DCs in which optical signals at two different wavelengths are coupled into two separate output channels. The developed approach ensures minimization of the crosstalk and overall DC length via simultaneous adjustment of the waveguide separation and length of the interaction region. As an example, the design of a DLSPPW-based DC for complete separation of telecommunication signals at the wavelengths lambda = 1400 nm and lambda = 1600 nm between two output channels separated by 6 mum is worked out, resulting in the total device length of 52.3 mum. In addition, the design of an ultracompact DLSPPW-based DC waveguide crossing that ensures a very low crosstalk over a large wavelength band in the telecommunication range is considered.     

宽壁耦合器的理论分析与设计

运用本征值法,经过详细的理论分析,提出一种新型的宽壁耦合器,它不需任何附加的阻抗匹配装置,实物测试结果表明其性能良好。     

宽带定向耦合器的设计与应用

对耦合线定向耦合器进行理论分析,对于对称型,首先求得多节定向耦合器的耦合度通用表达式,然后利用二项式(最平坦)响应前n-1阶导数为零的条件,计算出各节耦合系数。对于非对称型,利用四分之一波长耦合器与四分之一波长阶梯阻抗滤波器等效,通过切比雪夫多项式及理查德变换综合出阶梯阻抗滤波器的归一化阻抗,此即为耦合器的偶模阻抗,然后计算出各节耦合系数。实例计算比较4~20 GHz的两种耦合器:二项式响应耦合器具有最平坦的带内特性;与二项式响应相同节数的切比雪夫响应耦合器具有更大的带宽比。最后用厚度为0.254 mm的Rogers 5880微带板制作了6~18 GHz的两节微带线耦合器,并应用在某组件中。     

一种内置FIFO全双工UART的设计与实现

针对处理器与UART接口速度不匹配,设计了一种内置先进先出存储器全双工通用异步收发器,提高了处理器和UART接口的效率。该设计包含发送模块、接收模块、波特率发生器模块、数据存储模块和总线接口模块。整个设计基于Quartus II平台,使用VHDL语言编程实现。经软件仿真,验证了该设计的正确性和可行性。     

Theory and Tables of Optimum Symmetrical TEM-Mode Coupled-Transmission-Line Directional Couplers

New equal-ripple polynomials were determined and applied to the synthesis of symmetrical TEM-mode coupled-transmission-line directional couplers (using exact methods). Tables of designs for symmetrical couplers of three, five, seven, and nine sections having mean couplings of -3.01, -6, -8.34, -10, and -20 dB, and having several equal-ripple tolerances in the coupling band are presented. Symmetrical maximally-flat directional-coupler designs having three, five, seven, and nine sections are also presented to complete the tables.     

光纤耦合器与速度干涉仪的灵敏度

通过改进光纤定向耦合器的结构,可以显著提高光纤速度干涉仪的灵敏度.该文从熔融拉锥型光纤定向耦合器的数学模型出发进行研究,详细分析了2×2和3×3型光纤定向耦合器在全光纤速度干涉仪(AFVISAR)中的具体作用,并对此两种结构的光纤速度干涉仪的性能(主要是灵敏度)的优劣进行了对比分析,表现出3×3型光纤定向耦合器构成的两端探测系统的优越性.最后提出采用N×N型光纤定向耦合器可能带来的光纤速度干涉仪性能的提高和适用局限性.     

X波段微带线定向耦合器的设计与模拟

提出了一种在X波段工作的高定向性的微带线定向耦合器结构,该结构在微带线两端和中间同时加入补偿电容以实现高定向性;随后我们分析了该种定向耦合器,推出了计算它的一系列表达式;最后通过ADS软件模拟得出了用该结构设计出的7dB定向耦合器的S参量,在12GHz中心频率下S11、S21、S31和S41分别为-44dB、-0．968dB、-6．997dB和-43．68dB,从而验证了理论分析的正确性。     

毫米波分支线定向耦合器的设计与优化

本文先介绍了分支线正交定向耦合器的概念与工作原理;然后根据该原理在ADS2009软件下设计仿真了工作在Ka波段的微带线定向耦合器,并对Ka波段的耦合器模型进行了改良,使之实际面积缩小的同时能达到原有的性能。     

LOC11X系列光耦合器的特性及应用

隔离放大电路在通信、工业、医疗器械、电源及测试装置等仪器中是十分关键的部件 ,它对整个系统的正常工作起着非常重要的作用。LOC11X系列线性光耦合器是美国CLARE公司生产的新型光耦合器 ,文中介绍该器件的工作原理同时给出了其在隔离放大电路中的应用方法。