MEMS微同轴宽带功分器

随着微波系统大功率、超宽带的发展,对功率分配/合成结构的性能提出了更高的要求,超宽带、低损耗、小尺寸、易于集成的功分器成为研究热点。基于微电子机械系统(MEMS)工艺的微同轴射频传输线具有超宽带、无色散、低损耗和高隔离度等特点,使用微同轴工艺制备的功分器具有超宽带、低损耗、易于集成、小型化和可移植性好等特点。仿真并制作了一款微同轴一分二功分器。测试结果表明,在6~18GHz内插入损耗小于0.3dB,功分器体积为3mm×5.85mm×0.5mm,功率容量不小于100W。通过包金带的方式装配了功分器的背靠背结构。测试结果表明,背靠背结构损耗与预期损耗相符。为微同轴功分器在100W有源功放组件中的应用奠定了基础。     

Design and High Performance of a Micromachined K -Band Rectangular Coaxial Cable

This paper presents the design and performance of a low-loss rectangular air-filled coaxial cable. A high-precision micromachining technique is used to fabricate the cable. It is assembled by bonding together five layers of gold-coated SU-8 photoresist fabricated using the ultraviolet photolithographic technique. As the cable is air filled, both the dielectric and radiation losses are negligible. The cross coupling is also very weak between the cable and other parts of the circuit in a system. These advantages make the proposed cable a very good candidate for low-cost high-performance miniaturized transmission lines. The cable is designed to work in the frequency range of 14-36 GHz, which covers the whole JC-band. The size of the cable is only 8.9 mm times 8.6 mm times 1.5 mm and the measured minimum insertion loss of the as-made cable is approximately 0.6 dB. The return loss is better than 15 dB in the passband.     

Tunable characteristics of ferrite composite right/left handed coplanar waveguide coupled line coupler – Measurement and experimental verification

This paper presents the experimental verification of the tunable characteristics of a ferrite composite right/left handed coupled line coupler. The coupler is designed using two coupled CRLH-CRLH transmission lines. The coupler is designed to demonstrate equal through and backward coupling. The novel coupler has been designed and realized in coplanar waveguide configuration on a ferrite substrate. The tunable characteristics are achieved by changing the applied DC magnetic bias to the ferrite substrate. The measurement results reveal that the coupler’s fractional bandwidth can be tuned from 29% to 69% by varying the applied DC magnetic bias from 1000 Oe to 1750 Oe. Within the tunable bandwidth, the maximum backward coupling is −5 dB. The coupler has high forward coupling isolation, close to −30 dB at its centre operating frequency. In addition to its tuning capability, the coupler has the advantages of its compact size; it has the length of 11.5 mm and not-so-tight line separations of 2.5 mm. Furthermore the coupler only requires low DC magnetic bias.     

A broadband and compact asymmetrical backward coupled-line coupler with high coupling level

A new wideband asymmetric microstrip coupled-line coupler with 3 dB coupling value and quadrature phase difference is presented. Compared with the conventional edge-coupled couplers, this structure, consisting of two different transmission lines (interdigital and conventional microstrip transmission lines) as coupled lines, achieves wider operating bandwidth and larger coupling level. The coupled-line length of the proposed structure is approximately λ_g/4. To characterize the structure, an equivalent circuit model has been established. A 3 dB designed and fabricated coupler with 0.2 mm spacing between coupled lines exhibits an amplitude balance of 2 dB from 2.2 GHz to 4.2 GHz. Good agreements between the full-wave simulation and equivalent circuit model results has been achieved and verified the effectiveness of the proposed circuit model. Also, measurement results have been presented.     

High-Efficiency Angled-Dipole Antennas for Millimeter-Wave Phased Array Applications

A high-efficiency microstrip-fed endfire angled-dipole antenna has been developed for millimeter-wave phased array applications. The antenna is built on both sides of a Teflon substrate (epsiv_r = 2.2) and this allows a wideband feed from the single-ended microstrip line to the differential dipole. The design results in wide radiation patterns for scanning purposes with a gain of around 2.5 dB at 20-26 GHz and a cross-polarization level of < -15 dB at 24 GHz. A mutual coupling of < -23 dB is measured between adjacent elements with 6.8 mm center-to center spacing (0.50-0.54 lambda₀ at 22-24 GHz). A variant of the angled-dipole antenna with a magnetic ground plane edge was also developed, and shows a measured gain of > 6 dB at 23.2-24.6 GHz and very low mutual coupling between elements (<-23 dB for a 6.8 mm spacing). Both antennas result in a radiation efficiency of > 93% when referenced to the microstrip line feed (including mismatch loss). The usefulness of these antennas as phased array radiators is demonstrated by several eight-element linear arrays at 22-24 GHz with scan angle up to 50 degrees. The application areas are in automotive radars and high data-rate communication systems.     

圆柱腔内多导体传输线的瞬态电磁响应

为提高系统抗强电磁脉冲毁伤能力,采用时域有限差分法(Finite Difference Tim e Domain,FDTD)和通用电路仿真器(SPICE)相结合的协同仿真方法,以圆柱腔内由单导线、 双绞线、普通双线和同轴线组成的线束为研究对象,重点研究了导线类型、导线间距、捆扎 和RC滤波电路对耦合特性的影响。结果表明：耦合系数受腔体和传输线的双重影响,同轴线 耦合系数较其他两类线缆降低约40 dB;线间相互屏蔽是捆扎降低耦合系数的主要原因 ;随着导线间距增大,耦合系数幅值增大;RC滤波电路是降低电磁耦合的有效手段。所得结 论对电子系统进行抗电磁脉冲加固具有重要意义。     

S 波段高性能微型滤波器的研究

应用LTCC多层耦合带状线谐振器和交叉耦合传输零点原理,在改进的三维梳状带通滤波器结构中引入交叉耦合,增强非相邻谐振级间的交叉耦合;在2、4谐振级间引入Z字形导体层,通过调节Z字形控制传输零点位置;同时适当调节加载电容大小,有效减小了滤波器体积,实现了高次谐波抑制、边带陡峭和通带内线性相位.采用低温共烧陶瓷(LTCC)技术设计制作了中心频率为3GHz,通带为200MHz的微型带通滤波器.实验和仿真结果表明,该滤波器的中心频率插入损耗小于2.6dB,阻带抑制高于40dB,边带陡峭,尺寸仅为4.8mm×4.2mm× 1.5mm.成品率高达85％.     

Analysis and Design of a Chip Filter With Low Insertion Loss and Two Adjustable Transmission Zeros Using 0.18- $mu{hbox{m}}$ CMOS Technology

This paper presents the structure of a high-selectivity bandpass filter that is fabricated on low-resistivity silicon substrate with a commercial CMOS technology. The filter is constructed using crossed coplanar waveguide (CPW) lines and metal–insulator–metal capacitors to ensure that it has the desired passband characteristics. An adjustable capacitor between the input and output ports is employed to form a capacitive cross-coupled path, yielding two transmission zeros in the lower and upper stopbands, respectively. Additionally, the coupling mechanism can be modified by turning on or off the gate of an nMOS transistor to adjust the positions of the transmission zeros by applying an externally controlled voltage. To obtain a low passband loss and to minimize the chip size, high-impedance CPW transmission lines are adopted. Our analysis indicates that the CPW line possesses more advantages than the preferred stacked-ground CPW line for constructing the proposed filter. A very compact $X$ -band experimental prototype with a size of ${hbox{0.88}}times {hbox{0.54}} {hbox{mm}}^{2}$ was designed and fabricated. The measurements reveal an insertion loss of less than 3.2 dB in the passband, which is from 10.6 to 12.7 GHz, and rejection levels greater than 35 dB at the designed frequencies of transmission zeros. Moreover, the lower and upper transmission zeros can be shifted from 5 to 6.5 GHz and from 18 to 21.4 GHz, respectively, by changing the controlled voltage.      

Characterization and attenuation mechanism of CMOS-compatible micromachined edge-suspended coplanar waveguides on low-resistivity silicon substrate

This paper presents detailed characterization of a category of edge-suspended coplanar waveguides that were fabricated on low-resistivity silicon substrates using improved CMOS-compatible micromachining techniques. The edge-suspended structure is proposed to provide reduced substrate loss and strong mechanical support at the same time. It is revealed that, at radio or microwave frequencies, the electromagnetic waves are highly concentrated along the edges of the signal line. Removing the silicon underneath the edges of the signal line, along with the silicon between the signal and ground lines, can effectively reduce the substrate coupling and loss. The edge-suspended structure has been implemented by a combination of deep reactive ion etching and anisotropic wet etching. Compared to the conventional silicon-based coplanar waveguides, which show an insertion loss of 2.5dB/mm, the loss of edge-suspended coplanar waveguides with the same dimensions is reduced to as low as 0.5 dB/mm and a much reduced attenuation per wavelength (dB//spl lambda//sub g/) at 39 GHz. Most importantly, the edge-suspended coplanar waveguides feature strong mechanical support provided by the silicon remaining underneath the center of the signal line. The performance of the coplanar waveguides is evaluated by high-frequency measurement and full-wave electromagnetic (EM) simulation. In addition, the resistance, inductance, conductance, capacitance (RLGC) line parameters and the propagation constant of the coplanar waveguides (CPWs) were extracted and analyzed.     

一种宽频带低损耗内监测网络的设计

介绍了一种小型化宽带低损耗内监测网络,该内监测网络位于相控阵雷达的T/R组件与天线之间,采用串馈形式,通过缝隙耦合将发射接收信号耦合输出。天线与组件之间的互联直通路采用同轴形式降低损耗,监测耦合路采用微带线形式减小体积,通过改变耦合缝隙的尺寸来调节耦合强弱,通过旋转耦合缝隙角度来调节耦合器的定向性,通过优化耦合区域微带线的线宽实现阻抗匹配。采用全波仿真方法对定向耦合器进行了优化设计,在12~18 GHz的频率范围内,端口的回波损耗均小于-20 dB,通带内耦合度在-32^-29.5 dB之间,定向性大于20 dB,性能指标优良;对所设计的内监测网络进行实物加工与试验验证,测试结果与仿真结果相吻合。     

Symmetric Reverse-Coupling Waveguide Orthomode Transducer for the 3-mm Band

We describe the design, construction, and performance of a waveguide orthomode transducer (OMT) for the 3-mm band (84-116 GHz). The OMT is based on a symmetric backward coupling structure and has a square waveguide input port (2.54 mm times 2.54 mm) and two single-mode waveguide outputs: a standard WR10 rectangular waveguide (2.54 mm times 1.27 mm), and an oval waveguide with full-radius corners. The reverse coupling structure is located in the common square waveguide arm and splits one polarization signal in two opposite rectangular waveguide sidearms using broadband -3-dB .E-plane branch-line hybrid couplers. The device was optimized using a commercial 3-D electromagnetic simulator. The OMT consists of two mechanical blocks fabricated in split- block configuration using conventional CNC milling machine. From 84 to 116 GHz, the measured input reflection coefficient was less than -17 dB, the cross polarization was less than -30 dB, the isolation between the outputs was greater than 50 dB, and the insertion loss was less than 0.35 dB at room temperature for both polarization channels. The device is suitable for scaling to higher frequency.     

A design technique for a 60 GHz-bandwidth distributed basebandamplifier IC module

A DC-60 GHz, 9 dB distributed amplifier IC module is fabricated with 0.15 μm InAlAs-InGaAs low-noise HEMTs with 155 GHz f_T and 234 GHz f_max. The device is mounted in a metal package with 1.8 mm coaxial cable signal interfaces. The package is specially designed using three-dimensional electromagnetic field analyses, resulting in very flat frequency characteristics of the module within 1.5 dB gain ripples over the entire bandwidth. A multichip module loaded with two amplifier ICs in cascade is also fabricated, and operates at a 17.5 dB gain from 60 kHz to 48 GHz. The 1 dB gain compression output power is about 5 dBm for both modules. The noise figure of the single-chip module is approximately 4 dB over a 10-40 GHz frequency range     

一种小型化的高隔离度UWB-MIMO天线

提出了一种紧凑、高性能、形状新颖的具有高隔离度的超宽带多输入多输出(ultra-wideband multiple-input multiple-output, UWB-MIMO)天线.天线由两个圆形辐射元件组成,享有共同的类F形接地平面,尺寸为30 mm×18 mm.在天线的接地平面中引入类F形短截线,在MIMO天线元件之间产生高度隔离.所设计的UWB-MIMO天线具有极低耦合(S₂₁<-22 dB)、低包络相关系数(ECC<0.003)、高分集增益(DG>9.98 dB),适用于便携式通信设备.     

CPW MMIC coupler based on offset broadside air-gap couplingfabricated by standard airbridge processes

A new low-loss CPW-based MMIC coupler is developed. Offset broadside coupling using the air gap between the two lines in employed to obtain tight coupling as well as low conductor loss. Moreover, the air-gap coupling is achieved using a standard MMIC airbridge process, eliminating the need for an additional dielectric process. The fabricated Ka-band coupler showed transmission and coupling losses of 3.6±0.4 dB over a wide frequency range from 20 to 39 GHz. This is better than the previous CPW coupler loss in this frequency range     

A new compact LTCC bandpass filter using negative coupling

This letter presents the design and realization of a new compact bandpass filter (BPF) fabricated on multilayered ceramic substrates. This BPF features coupled resonators with negative coupling coefficients. A BPF with center frequency 2.45 GHz is designed and fabricated. Its size is only 2.0 mm/spl times/1.8 mm/spl times/0.67 mm when implemented by a standard low temperature co-fired ceramic technology. The size reduction is due to the higher coupling coefficient between the negatively-coupled resonators than the positively-coupled ones, allowing tighter space between the resonators. The measured insertion losses of the previous BPF were less than 3dB and return losses more than 18dB in the passband. The measured result agrees very well with the electromagnetic (EM) designed response.     

Coaxial transitions for CPW-to-CPW flip chip interconnects

A novel coaxial transition for CPW-to-CPW flip chip interconnect is presented and experimentally demonstrated. To realise the coaxial transition on the CPW circuit, benzocyclobutene was used as the interlayer dielectric between the vertical coaxial transition and the CPW circuit. The coaxial interconnect structure was successfully fabricated and RF characterised to 67 GHz. The structure showed excellent interconnect performance from DC up to 55 GHz with low return loss below 20 dB and low insertion loss less than 0.5 dB even when the underfill was applied to the structure.     

一种新型的双L 型基片集成同轴互连阵列

基片集成同轴线(Substrate Integrated Coaxial Line,SICL)是一种由基板上下导体板、内导体和金属化过孔阵列构成的集成波导结构,具有低损耗、宽频带、抗干扰、易于集成等优点。本文在基片集成同轴线的基础上提出了一种新型的双L型基片集成同轴互连阵列结构。首先通过仿真将它与传统的微带线和带状线进行了对比,结果表明该结构在损耗、反射以及隔离度方面均表现出优良的特性。然后采用低温共烧陶瓷(LTCC)工艺实现该结构,并通过实验测试了该样品的S参数、隔离性能、眼图及误码率。实验结果表明,在1~40GHz的频率范围内,双L型基片集成同轴互连阵列的耦合度在-40 d B以下,传输速率可达到30 Gbps,具有高速数据传输能力。     

A new class of nonuniform, broadband, nonsymmetrical rectangular coaxial-to-microstrip directional couplers for high power applications

An innovative class of coaxial-to-microstrip broad-band high power directional couplers is studied. The new devices overcome the drawbacks of both stripline and coaxial couplers and allow simple and low cost mechanical construction. In this letter, we present the design, realization and characterization of a set of broad-band (900 MHz to 5.5 GHz) low coupling (-30 dB, -40 dB) directional couplers with directivity of more than 10 dB over the whole band, demonstrating good agreement between predicted and obtained performances.     

Mode Selective Coaxial Directional Couplers for Harmonic Measurements

Bethe's small-hole coupling theory is applied to coaxial transmission line to design mode selective directional couplers. By independently sampling the TEM and TE11 modes in coaxial line, harmonic measurements can be performed which would require five or more directional couplers if made in rectangular waveguide. Mode selectivity on the order of 30 dB has been achieved.     

面向卫星通信的内导体非接触同轴接头设计方法

针对无源互调(PIM)严重影响卫星通信系统性能和稳定性问题,提出了一种利用内导体非接触式结构实现低PIM的同轴接头设计方法。设计并实现了2款分别工作在S波段和C波段的内导体非接触式同轴接头：S波段的内导体非接触式同轴接头在2.1~2.7 GHz下实测|S₁₁|<-30 dB,通带内插入损耗小于0.3 dB;C波段的内导体非接触式同轴接头在3.5~4.2 GHz下实测|S₁₁|<-30 dB,通带内插入损耗小于0.2 dB。该改进型同轴接头设计方法为卫星通信系统的微波连接器的设计提供了重要的参考价值和新的研究思路。