高隔离度Ka波段平面魔T的设计

提出了一种适合于毫米波微波集成电路(M IC)的高隔离度平面魔T结构,该结构属于一种新型的180°平面型混合网络。基于传统的微带混合环原理,引入了微带-槽线过渡的结构,两个端口之间的180°相移通过微带-槽线转换结构实现,从而实现了输出端口的隔离。该结构采用多节阻抗匹配网络,增加了工作带宽,使微带-槽线过渡结的寄生耦合最小化。通过设计可实现得到最小尺寸的槽线终端,降低了微带-槽线过渡结的辐射损耗。引入的等效电路模型有效地提高了平面魔T的设计。借助CST软件,仿真优化了λg/4变换器以及微带-槽线转换结构的阻抗匹配,提高了隔离度。实验结果表明:在工作带宽(34～36 GHz)内,该结构输出端口2和3的隔离度达20 dB,输入端口回波损耗低于18 dB,插入损耗1 dB。     

基于准对称性的超宽带八端口和差器设计

和差器在雷达领域具有广泛的应用。 文中首先对八端口和差器的工作原理进行了介绍,同时提出了端口准对称性的新概念,并进行了理论分析和论证。 在端口准对称性的基础上提出一种超宽带八端口和差器的整体设计方案,使多个设计参数简化为一个设计参数,极大地简化了八端口和差器的设计。 实际加工了一款基于双面平行带线的超宽带八端口和差器,中心频率为 3 GHz,工作频率为 1. 5 GHz~ 4. 5 GHz( -10 dB 以下),相对带宽为 100%,相位误差在±4°以内。测试结果与仿真结果和理论分析结果相符,验证了所提理论的正确性。     

一种新型微带/槽线混合结构的宽带魔T

提出一种新型宽带平面魔T结构,该魔T基于传统的微带混合环的原理设计而成,为扩展工作频带,采用了微带-槽线混合结构,通过将槽线T接头功分器的反相输出特性与微带T接头功分器的同相输出特性相结合,从而实现两输出端口的宽带和/差输出。测量数据表明该魔T结构可实现超过25%的相对工作带宽(输入端口回波损耗低于-10dB),在工作频带(4.3~5.6GHz)内,其传输插损小于1dB,两对隔离端口的隔离度分别为-30dB和-20dB。     

A Broadband Planar Magic-T Using Microstrip–Slotline Transitions

The improved version of a broadband planar magic-T using microstrip-slotline transitions is presented. The design implements a small microstrip-slotline tee junction with minimum size slotline terminations to reduce radiation loss. A multisection impedance transformation network is used to increase the operating bandwidth and minimize the parasitic coupling around the microstrip-slotline tee junction. As a result, the improved magic-T has greater bandwidth and lower phase imbalance at the sum and difference ports than the earlier magic-T design. The experimental results show that the 10-GHz magic-T provides more than 70% of 1-dB operating bandwidth with the average in-band insertion loss of less than 0.6 dB. It also has phase and amplitude imbalance of less than plusmn1deg and plusmn0.25 dB, respectively.     

Novel configurations of planar multilayer magic-T usingmicrostrip-slotline transitions

Novel configurations of microwave planar magic-T suitable for microwave integrated circuits (MICs) and monolithic MICs are described. They consist of microstrip and slotline T-junctions coupled by microstrip-slotline transitions. Since via-hole processing is not encountered, they are especially applicable to multilayer MICs. Derived equivalent network models are used efficiently for the design of the corresponding multilayer microstrip magic-T. Measured data and numerical simulations showing good amplitude and phase characteristics over an octave operating bandwidth validate the proposed configurations of planar magic-T     

Analysis of broadband microstrip-slotline transitions withmulti-arm stubs

For a compromised design of microstrip-slotline transitions with multi-arm stubs, the relation between the number of arms and the bandwidth is necessary. This issue is examined using a modelling technique based on the equivalent circuit of the transition. The technique is used to analyse two broadband (1-10 GHz and 5-50 GHz) transitions with stubs having different number of arms     

Reactances of slotline short and open circuits on alumina substrate

Resonant techniques have been employed to determine the equivalent normalized reactance of slotline planar short circuits and open circuits realized on alumina substrates. Data for slotline short circuits are presented in a graph covering a wide range of normalized slot widths. Characteristics of several slotline open circuits are given, demonstrating their resonant behavior and the resulting bandwidth limitation. As an example of an application, the design of broadband microstrip-slotline transitions employing experimentally characterized slotline open circuits is outlined     

一种平面魔T结构的研究

为在小体积范围内产生雷达和信号、差信号,介绍了一种宽带平面型魔T结构的实现方法。通过选取合适的电路结构,并借助微波EM分析软件,在微带线和槽线的基板上实现了平面型魔T结构电路功能,在较宽的频带内实现了良好的幅相特性,并给出了测试结果。同时表明作为一种传输线结构二槽线,有其独特的优点和应用价值。     

Gain and bandwidth of fast near-infrared photodetectors: A comparison of diodes, phototransistors, and photoconductive devices

Different materials and different types of detectors are used for optical data communication in the wavelength range oflambda sim 0.8µmlambda sim 1.7µm. In this paper the behavior of p-n diodes, Mn and Mp Schottky diodes is evaluated as well as that of bipolar transistors, n-p-n and p-n-p, and of photoconductive detectors using n-type or p-type material. The different behavior of lateral and coaxial versions is shown taking into account contact and surface recombination. The gain, the bandwidth, the gain bandwidth product, and the rise time of all these types of fast detectors are given in terms of material and technological data, including the discussion of the different rise and fall times of some detector versions. Finally, a theoretical comparison is made between the detectors showing their different behavior and ultimate performance limit. For practical GaAs planar devices as a photoconductive detector, a p-n diode, a heterojunction n-p-n and a lateral n-p-n transistor, a Mn Schottky diode, and a totally depleted MnM structure (symmetrical Mott barrier) experimental data are given. They verify the theoretical prediction that with all types of detectors rise times of <100 ps can be achieved.     

Circulators Using Planar WYE Resonators

An important class of commercial three-port circulator relies for its operation on a junction resonator consisting of the symmetrical connection of three open-circuited transmission lines. A feature of this resonator is that it may be quarter-wave coupled to form a circulator with a moderate specification (25-percent bandwidth to 25-dB return loss points) and physical dimensions of the order of directly coupled conventional circulators (using a disk resonator). For circulators for which the in-phase eigennetwork may be represented by an ideal short-circuit, the equivalent circuit is a one-port network which may be formed from a characterization of the constituent resonator. This feature is used in this paper to study the equivalent circuit of junction circulators using planar WYE resonators. The derivation of the equivalent circuit parameters is supported with the design of a 4-GHz quarter-wave-coupled stripline circulator.     

Improved circuit implementation of adaptive phase comparators

An improved implementation of an adaptive phase comparator circuit is presented. The adaptive phase comparator can be thought of as a five-cell up-down counter that is bounded in both the outermost cells. A new design concept leads to a circuit with a higher maximum operation frequency while maintaining the basic requirements of handling coincident input signals and absence of intermediate states. The circuit is based on the application of a number of identical logic elements, which are placed in a ring structure     

Computer-Oriented Synthesis of Optimum Circuit Pattern of 3-dB Hybrid Ring by the Planar Circuit Approach

A fully computer-oriented synthesis of the optimum circuit pattern of a 3-dB hybrid ring based upon the planar circuit concept is described. In the synthesis process, the contour-integral method, and Powell's method are used for the circuit analysis, the optimization, respectively. The synthesized optimum patterns are given in normalized curves, parameters which can directly be used in practical circuit design. The validity of the theory is confirmed by experiment. It is shown both theoretically, experimentally that the planar circuit approach can, not only prevent the deterioration of the hybrid characteristics due to the widening of the circuit, but bring forth hybrid characteristics somewhat better than the distributed constant model. It is also shown that the obtained optimized characteristics can further be improved by addition of simple external circuits.     

A high bandwidth constant gm and slew-rate rail-to-railCMOS input circuit and its application to analog cells for low voltageVLSI systems

A new rail-to-rail CMOS input architecture is presented that delivers behavior nearly independent of the common-mode level in terms of both transconductance and slewing characteristics. Feedforward is used to achieve high common-mode bandwidth, and operation does not rely on analytic square law characteristics, making the technique applicable to deep submicron technologies. From the basis of a transconductor design, an asynchronous comparator and a video bandwidth op amp are also developed, providing a family of general purpose analog circuit functions which may be used in high (and low) bandwidth mixed-signal systems. Benefits for the system designer are that the need for rigorous control of common-mode levels is avoided and input signal swings right across the power supply range can be easily handled. A further benefit is that having very consistent performance, the circuits can be easily described in VHDL (or other behavioral language) to allow simulation of large mixed-signal systems. The circuits presented may be easily adapted for a range of requirements. Results are presented for representative transconductor, op amp, and comparator designs fabricated in a 0.5 μm 3.3 V digital CMOS process     

一种由渐变缝隙天线构成的等效全向天线

介绍了一种以斜角微带-缝隙过渡馈电的渐变缝隙天线。渐变缝隙天线具有平面结构、带宽较宽、增益适中等优点;斜角微带-缝隙过渡形式简洁,在工艺上易于实现。将几个这样的渐变缝隙天线以放射状构成一圈,并在它们的馈线上引入一组PIN开关,以适当的时序控制PIN开关依次切换,可构成一种等效的全向天线。这种天线结构简单,占用空间小,很适合弹载应用。     

Properties of the Symmetrical Circuit and its Broad-Band Five-Port Design

The properties of the mismatched symmetrical five-port circuit are discussed, i.e., the equations for the maximum and minimum couplings of a mismatched symmetrical five-port circuit are derived by appropriate approximations. The approximate equations for the maximum and minimum phase differences due to mismatches of a symmetrical five-port circuit are also derived. Furthermore, a broad-band design theory of a symmetrical five-port circuit with microstrip line is propsed by applying a matching technique which adds a generalized compensating network and matching sections to the fundamental symmetrical five-port circuit. Thus, the bandwidth of the proposed broad-band symmetrical five-port circuit extends to about an octave. The experimental verification has been achieved, and, hence, the validity of the design method is confirmed.     

具有高共模抑制特性的微带差分带通滤波器

该文提出了一款中心频率可调的三阶差分带通滤波器,该滤波器主要由1个折叠的枝节加载谐振器(FSLR)和1对折叠的平行耦合线结构来实现滤波特性,同时使用微带-缝隙线转换结构激励差模和抑制共模。与传统的微带滤波器相比,该结构的共模响应和差模响应无关,所以在不降低差模特性情况下实现了良好的共模抑制,使设计更灵活。该差分滤波器整体尺寸为26 mm×49.2 mm,中心频率为3 GHz,相对带宽可达28.67%,共模抑制水平优于37 dB。结果表明,实际测量结果与仿真结果基本吻合。     

A Compact Broad-Band Thin-Film Lumped-Element L-Band Circulator

Impedance matrices including magnetic losses are developed for a number of lumped-element ferrite-loaded symmetrical three-port junctions. The scattering matrix eigenvalues corresponding to these matrices are determined as functions of frequency and circuit parameters and are used to analyze these three-ports with emphasis on their properties as circulators. A very compact broad-band thin-film lumped-element circulator is derived from the idealized equivalent circuit. An experimental model approximately represented by this circuit is shown to have a 20-dB isolation bandwidth of greater than 30 percent with an insertion loss of less than 0.6 decibel. A switchable circulator which requires no magnetic-field switching is treated using this same analytical approach. It is suggested that this type of analysis together with additional experimental refinement of equivalent circuits will lead eventually to a computerized design of lumped-element circulators.     

Design and performance of a planar star mixer

This paper describes the realization of a hybrid star mixer as a planar circuit. The mixer has a minimum conversion loss of 5 dB and, for a conversion loss of less than 9 dB, spans over 2.2 GHz in IF bandwidth and 8 GHz in RF/LO bandwidth. The mixer employs a novel, planar balun structure, similar to conductor-backed CPW, that is suitable for realization as a monolithic circuit     

一种新型多周期平面电磁带隙结构

根据不同周期平面电磁带隙(EBG)结构所具有的不同带隙特性以及平面EBG结构的等效电路,提出一种新型多周期平面EBG结构。通过Ansoft HFSS软件对该EBG结构的电磁带隙特性进行仿真验证。结果表明:所提出的EBG结构抑制深度为-30dB时,阻带范围为0.7～8.4GHz,阻带宽度为7.7GHz.相对于传统大周期和小周期平面EBG结构,其阻带宽度分别增加2.1GHz和1.2GHz.仿真结果也表明新型EBG结构可以有效抑制同步开关噪声(SSN),并为展宽平面EBG结构的禁带带宽提供一种新方法。最后,通过时域仿真验证新结构具有较好的信号完整性。     

可用于Class D的电流反馈比较器设计

设计一款可用于Class D的比较器。在考虑抗噪能力和分辨率的情况下,引入2路电流反馈,提高抗噪能力,从而可以提高分辨率。采用HHNEC BCD035工艺对该调制器进行电路级设计并用Cadence仿真,该电路可抑制输出电压的错误跳变,失调电压为0.2 mV,增益为38.42 dB,3 dB带宽达到20 MHz,满足高速率要求。