无源超高频电子标签射频模拟前端设计

基于对射频识别技术（RFID）物理基础的介绍,并阐述射频识别技术（RFID）的作用范围,介绍了无源超高频电子标签射频模拟前端设计的实现原理框图。通过对ISO 18000.6B协议相关规定的分析,合理地确定了模拟前端和射频前端各个模块的设计指标,并就这些规定的指标设计出了中心频率为915MHz的无源超高频电子标签芯片射频模拟前端。     

一种小体积X波段频率合成器设计

介绍了一种小体积频率合成器的设计，该频率合成器通过直接数字频率合成器（DDS）产生线性调频信号，通过锁相环产生固定二本振信号，通过锁相环（PLL）与2 倍频器产生一本振信号，通过变频部分完成二次混频产生射频激励信号。同时采用现场可编程门阵列（FPGA）完成DDS 控制以及与系统通讯，电源控制部分产生各种电源。     

一种频率合成器的建模优化与电路设计

根据数模混合集成电路系统级和行为级快速验证的需求,设计了一种卫星导航系统射频接收机前端的频率合成器。传统行为级模型一般是基于理想环路进行参数提取,误差较大。为此,首先,分别利用MATLAB和Verilog-AMS对频率合成器建立理想行为级模型与非理想行为级模型,并根据行为级模型提取与优化的环路参数,采用SMIC 180 nm CMOS工艺设计仿真电路级频率合成器;其次,建立MATLAB噪声模型,对电路级各个模块的噪声进行拟合,评估频率合成器系统的整体噪声性能。所提出的频率合成器设计方法对电路级设计具有前瞻性的指导,并有助于电路级的设计优化。     

正弦结构：构成精密振荡器的DDS技术

直接数字频率合成器（DDS）可为从次声波到射频（RF）的各种应用提供快速的相位相干与线性调谐。     

射频前端接收机频率规划

在无线通信系统的片上系统（SoC）设计中，模拟射频前端高层次仿真、综合和优化的工具还不成熟，制约了整个系统的开发周期。射频前端的频率规划直接影响系统的复杂度、集成性和功耗，目前的频率规划主要是由经验丰富的设计师根据经验和直觉确定，而不是通过量化分析。本文在射频前端设计方法的基础上，以定量优化的方法处理射频前端频率规划问题，提出了两级优化模型，补充和完善了以往提出的射频前端设计方法。     

UHF宽带数字频率合成器的设计

频率合成器在现代电子系统中应用日益广泛,UHF（超高频）宽带数字频率合成器是地囿数字电视广播覆盖网的重要设备——数字电视激励器和转发器中的主要组成单元。提出了一种UHF宽带小频率步进、低相噪数字频率合成器的设计方法,介绍了系统各部分的设计方法、器件选择、相关参数的计算及PCB（印制电路板）设计,最后给出了系统射频输出信号相噪测试结果,验证了本设计方法的有效性和设计方案的可行性。     

一种UHF频段无线数据传输系统接入点的射频前端

介绍了UHF(特高频)频段无线数据传输系统中接入点的一种射频前端。该前端包括调制器、上变频器、功率放大器、低噪声放大器、下变频器、解调器、频率合成器、增益控制和收发切换开关等电路。介绍了射频前端的实现方案以及关键部件的设计与测试。制作完成的射频前端集成在一块1 5 0mm×1 0 0mm的4层印制电路版上。该前端最大输出功率可达2W,接收灵敏度优于-100 dBm,收发切换时延小于1.5μs,满足系统指标要求。     

IS-95 CDMA手机射频前端频率合成器的设计．

本文针对ＩＳ－９５ＣＤＭＡ后机射频前端频率合成器频率间隔小，分频比大，频率稳定度高等要求，提出了解决方案。文中讨论了环路滤波器的设计，相对位噪声和锁定时间进行分析，最后得到了与分析符合的较好的结果。     

基于DDS的RFID频率合成器设计

随着相关技术的不断完善和成熟,RFID 产业将成为一个新兴的高技术产业群,成为国民经济新的增长点.该文根据EPCglobalTM Class 1 Generation 2标准中有关RFID跳频频率的规定,结合RFID射频前端的开发要求,设计出一款新型的RFID频率合成器.频率合成器以Analog Devices Inc公司的时钟集成电路AD9540(内含DDS模块)为核心,通过单片机AT89C51加以配置及控制.输出的DDS跳频信号与800 MHz信号混频得到射频前端所需的832～858 MHz跳频信号,通过滤波及放大最终输出.实验证明,基于DDS的跳频速度快,频率精确度高,各方面性能指标符合标准要求.     

变电站智能解锁钥匙射频前端设计

变电站解锁钥匙管理不规范引起的电气误操作事故愈来愈多,针对这一现状提出了RFID变电站智能解锁钥匙的方案,文章介绍了变电站智能钥匙的天线设计及射频前端的电路设计。并通过对EM4100编码的识别验证了电路的可靠性。     

A Dual-Fed, Self-Diplexing PIFA and RF Front-End

A dual-fed, self-diplexing planar inverted F antenna and an associated RF front-end are described. It is shown that co-design of the antenna and front-end can be used to double the operational bandwidth, without significant size or performance penalties. Indeed, the use of two feeds allows the antenna to be self-diplexing, which results in improved overall efficiency     

A Unified Mutual Coupling Model for Multiple Antenna Systems

The use of multiple antennas can offer substantial performance improvement to a wireless communication system by spatial multiplexing methods or diversity methods[1]. In the multiple antenna receivers, each antenna requires another Radio-Frequency (RF) front-end chain. To achieve high multiple antenna gain, the multiple received signals arriving at the Combined Signal Processor (CSP) module should be independent and hold balanced mean power[2]. There are several factors affecting the corre…     

Packaging technique for gain enhancement of electrically smallantenna designed on gallium arsenide

A novel method is presented for achieving a complete RF front end product equipped with its radiator within a single chip package. This packaging technique provides an alternative solution to problems associated with reduced size antennas implemented on gallium arsenide (GaAs) substrates, such as restoration of the antenna gain by 15 dB. This configuration will help to reduce manufacturing costs associated with connecting the antenna to the RF front-end chip     

Millimeter-Wave Soldier-to-Soldier Communications for Covert Battlefield Operations

Mobile ad hoc networking of dismounted combat personnel is expected to play an important role in the future of network-centric operations. High-speed, short-range, soldier-to-soldier wireless communications will be required to relay information on situational awareness, tactical instructions, and covert surveillance related data during special operations reconnaissance and other missions. This article presents some of the work commissioned by the U.K. Ministry of Defence to assess the feasibility of using 60 GHz millimeter-wave smart antenna technology to provide covert communications capable of meeting these stringent networking needs. Recent advances in RF front-end technology, alongside physical layer transmission schemes that could be employed in millimeter-wave soldier- mounted radio, are discussed. The introduction of covert communications between soldiers will require the development of a bespoke directive medium access layer. A number of adjustments to the IEEE 802.11 distribution coordination function that will enable directional communications are suggested. The successful implementation of future smart antenna technologies and direction of arrival-based protocols will be highly dependent on thorough knowledge of transmission channel characteristics prior to deployment. A novel approach to simulating dynamic soldier-to-soldier signal propagation using state-of-the-art animation-based technology developed for computer game design is described, and important channel metrics such as root mean square angle and delay spread for a team of four networked infantry soldiers over a range of indoor and outdoor environments is reported.     

一个基于软件无线电的智能天线接收系统

智能天线技术是第三代移动通信中的核心技术之一,最初主要应用于雷达和军用抗干扰通信。随着软件无线电技术的发展,采用全数字处理,在基带通过对接收和发送信号的波束赋形,可以极大提高无线通信系统的容量和抗干扰能力。文中在讨论智能天线的基本原理和设计思路的基础上,提出并实现了一个适于扩频通信的智能天线接收系统。系统硬件平台的搭建以及固定波束形成的实现,为以后的软件算法的性能评估打下了基础。     

RF Front-End Passive Circuit Implementation Including Antenna for ZigBee Applications

This paper presents a front-end passive circuit module for ZigBee applications using low-temperature co-fired ceramic technology. The front-end part consists of an antenna, a bandpass filter, a switch, and two baluns. In antenna design, the solenoid shape is employed for reducing the size of the antenna, resulting in an overall size of 9times16.4times1.82 mm³ and a gain of -1.4 dBi. As for the filter, two types of filters are suggested. First, the lumped-type filter employing a high-Q spiral inductor has more than 20-dB attenuation at both stopbands, very near to the passband. Secondly, the semilumped-type filter adopting an edge coupled line and a loading capacitor provides a group delay of below 5 ns and is adequate for the full module structure due to the structure flexibility. A balun is evaluated using lumped components instead of a transmission line and, thus, it provides an insertion loss of only 0.3 dB and a phase difference of 180deg between balanced signals. Based on these components, an RF front-end module including attaching pads for an RF integrated circuit (IC) and baseband IC is implemented. In case of using the lumped-type filter, the insertion loss of the front-end module is 6.5 dB, and the group delay is below 7 ns. In case of adopting the semilumped-type filter, the insertion loss is 6.2 dB, and the group delay is below 4 ns. The overall size of the former and latter is 25.14times28.5times0.68 mm³ and 25.66times25.58times1.17 mm³, respectively     

An LTCC-Based Wireless Transceiver for Radio-Over-Fiber Applications

This paper describes the realization of a low-temperature co-fired ceramic (LTCC)-based wireless transceiver with optical interface for radio-over-fiber applications involving several standards. The RF front-end including an antenna is fabricated in LTCC technology, while the optical transceiver with a single-mode optical interface is built on a silicon motherboard. The front-end operates in the 5-6-GHz band, while the modulated optical carrier is transmitted at 1.55-mum wavelength. The front-end module is an attractive solution for wireless local area network applications such as IEEE 802.11a or HIPERLAN2 requiring a direct link to an optical backbone     

Broadband Active Receiving Patch With Resistive Equalization

The active integrated antenna (AIA) concept has been applied to design a broadband receiver front-end. A design procedure for active broadband patch antennas based on resistive equalization is presented. The use of the AIA has allowed the design of efficient RF front-ends by increasing its effective gain, noise figure, and merit . In addition to improving the classical parameters, the resistive equalization technique allows enlarging the bandwidths of the active antenna parameters versus the corresponding ones in passive antennas. A receiving patch antenna (with one amplifying stage) with a measured noise figure lower than 0.6 dB in a bandwidth over 38% and an effective gain improvement of 13 dB over the corresponding passive antenna has been achieved. The -parameter has also been measured for both the active and passive antenna, resulting in a relative planar of 16 dB/K, with a ripple of 0.5 dB, over a 30% bandwidth for the active antenna versus a of 22 dB/K for a typical front-end with a passive antenna over 20% bandwidth.     

An efficient integration of GPS and WCDMA radio front-ends

An efficient integration of global positioning system (GPS) and universal mobile telecommunication system (UMTS) radio front-end units is presented. The combined front-end unit includes the transmitter and receiver filters, duplex filter, power amplifier, buck regulator, and power detector for the UMTS wireless code-division multiple-access system. The GPS building blocks of the radio front-end unit consist of the low-noise amplifier and RF filter. The inter-system isolation was experimentally quantified and the compared against the minimum inter-system isolation requirements, defined according to desensitization and intermodulation tests in the GPS receiver. The characterized isolation of the antenna array provided 6 dB of margin over the minimum inter-system isolation requirements for 3-dB degradation of the carrier-to-noise ratio in GPS receivers. The UMTS portion of the radio front-end unit was verified against the Third-Generation Partnership Project standard.     

Array Calibration for CDMA Smart Antenna Systems

In this paper, we investigate array calibration algorithms to derive a further improved version for correcting antenna array errors and RF transceiver errors in CDMA smart antenna systems. The structure of a multi‐channel RF transceiver with a digital calibration apparatus and its calibration techniques are presented, where we propose a new RF receiver calibration scheme to minimize interference of the calibration signal on the user signals. The calibration signal is injected into a multichannel receiver through a calibration signal injector whose array response vector is controlled in order to have a low correlation with the antenna response vector of the receive signals. We suggest a model‐based antenna array calibration to remove the antenna array errors including mutual coupling errors or to predict the element patterns from the array manifold measured at a small number of angles. Computer simulations and experiment results are shown to verify the calibration algorithms.