Monolithic SiGe Up‐/Down‐Conversion Mixers with Active Baluns

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on‐chip 1 to 6 GHz up‐conversion and 1 to 8 GHz down‐conversion mixers using a 0.8 µm SiGe hetero‐junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up‐conversion mixer was implemented on‐chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up‐conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down‐conversion mixer was implemented on‐chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down‐conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.     

The sinuous antenna-A dual polarized feed for reflector-based searching systems

The sinuous antennas have a numerous applications in military and civil systems such as direction finding systems and reflector feeds due to their superior broadband characteristics and simultaneous polarization capability. In this paper, design, construction and measurements of planar sinuous antennas are investigated for 1–5 GHz frequency range. Feeding sections of this antenna are realized by using microstrip tapered baluns. We have determined the microstrip tapered balun dimensions using Ansoft HFSS-simulation program. The performances of the manufactured antenna are measured using HP vector network analyzer. Polarization patterns and return loss characteristics of the designed antenna that have been measured in anechoic chamber, are presented.     

一种变压器巴伦馈电的超短波紧耦合阵列天线

紧耦合阵列天线(Tightly Coupled Array, TCA)具有超宽带、低剖面、宽角扫描等特点,近年来受到国内外学者的广泛关注。然而,在甚高频(VHF)、特高频(UHF)频段TCA 由于馈电网络设计困难等原因现有的研究报道很少。为了填补这一空白,本文设计并测试了一款变压器巴伦馈电的TCA,利用变压器巴伦解决了单元平衡馈电困难问题,同时采用短路枝节抑制E面共模谐振,采用频率选择表面(FSS)匹配层改善宽角扫描阻抗匹配。实测结果表明,该天线在110~520 MHz 频带内、±40°扫描角范围内电压驻波比<2.5,和仿真结果吻合。     

一种加载铁氧体磁环的高功率宽带巴伦

针对高功率天线的差分馈电和阻抗匹配问题,文中提出了一种基于同轴线结构加载铁氧体磁环的宽 带巴伦模型。双同轴线具有阻抗变换功能和较好的功率承载能力,铁氧体磁环改善了巴伦在低频时的输入匹配和 两个输出端口不平衡度。仿真和实测表明,此巴伦在0. 05~1. 24 GHz 内回波损耗低于-10 dB,去除3. 0 dB 系统插损 后单端插入损耗在1. 5 dB 以内,两端输出的相位不平衡度在5°以内,幅度不平衡度在2%以内。通过分析巴伦的电 磁热损耗场、温度场和应力形变场,验证了巴伦在高功率馈电下的工作性能,结果表明此巴伦在工作频带内能够承 受500 W 的功率。     

Wideband LC balun transformer using coupled LC resonators embedded into organic substrate

In this paper, wideband LC balun using coupled LC resonator has been newly designed, simulated, and fabricated. The proposed balun has a novel scheme which consists of two pairs of coupled embedded LC resonators which share one resonator with each other. The coupled resonators are applied to provide a precise phase difference of 180° and an identical magnitude between two balanced ports and DC isolation characteristic with impedance transformation. Furthermore, proposed resonators have relatively small inductance values which can be easily embedded into the organic package substrate. In order to reduce the size of embedded capacitors, BTO composite high dielectric film was applied to increase their capacitance densities. The measured results of fabricated wideband balun exhibited an insertion loss of 1.8 dB, a return loss of 10 dB, a phase imbalance of 0.5°, and magnitude imbalance of 0.7 dB at frequency bandwidth of 700 MHz ranged from 1.8 to 2.5 GHz, respectively. They agreed well with the simulated ones. The fabricated balun has a relatively small volume of 2 mm×3.5 mm×0.66 mm (height).     

低轨道小卫星通信中谐振式四臂螺旋天线的应用研究

谐振式四臂螺旋天线由于不需要参考地、能产生赋形方向图且重量轻、尺寸小,在空间通信中得到广泛的应用.本文从低轨道小卫星通信系统的要求出发,设计了两种实际的谐振式四臂螺旋天线,天线采用了新颖的90°自相移结构及平衡馈电结构.最后采用有限元方法对其辐射特性进行分析,计算结果与测试数据的一致性好.     

宽频带微带传输线巴伦的研究

对具有宽频带特性的微带传输线巴伦进行了研究,并应用微波网络优化理论对其进行了详细的理论分析与设计,数值计算结果与有关文献一致。最后,设计并制做了具有十倍频程的微带传输线巴伦,举例说明了本文方法的有效性。     

一种新型的超宽带微带转共面带状线巴伦

设计了一种新型的微带转共面带状线（coplanarStripLine以下简称CPS）的巴伦结构。它可以应用于多种常用的介质板上,具有结构紧凑、超宽带、低损耗的特点。制作了一个两端为500微带线的背靠背电路,测试得插入损耗（S21）〉-1dB、回波损耗（S11）〈-15dB的带宽为2．7GHz～7．3GHz,S21〉-4dB、S11〈-10dB的带宽为1．4GHz～15．6GHz。     

新型平面树状分形偶极子贴片天线的设计

提出了一种采用弧形分支的新型树状分形偶极子天线,简要介绍了树状分形天线的研究进展,设计了一种新型树状分形天线,并采用一种简单的巴伦馈电结构.二阶分形天线与0阶相比,工作频率下降了37.5%.对二阶分形天线进行了实物加工与测量,实验结果与仿真结果吻合较好.     

一个应用于卫星导航接收机的低功耗可配置双频多模射频前端

本文给出了一个应用于GPS、北斗、伽利略和Glonass四种卫星导航接收机的高性能双频多模射频前端。该射频前端主要包括有可配置的低噪声放大器、宽带有源单转双电路、高线性度的混频器和带隙基准电路。详细分析了寄生电容对源极电感负反馈低噪声放大器输入匹配的影响,通过在输入端使用两个不同的LC匹配网络和输出端使用开关电容的方法使低噪声放大器可以工作在1.2GHz和1.5GHz频带。同时使用混联的有源单转双电路在较大的带宽下仍能获得较好的平衡度。另外,混频器采用MGTR技术在低功耗的条件下来获得较高的线性度,并不恶化电路的其他性能。测试结果表明：在1227.6MHz和1557.42MHz频率下,噪声系数分别为2.1dB和2.0dB,增益分别为33.9dB和33.8dB,输入1dB压缩点分别0dBm和1dBm,在1.8V电源电压下功耗为16mW。