高线性度上变频混频器设计

首先介绍了二次变频接收机的架构及其优点,随后采用Gilbert单元设计了适用于二次变频结构数字电视调谐器的上变频混频器。基于Chartered 0.25／μmCMOS工艺的仿真结果显示该混频器达到了良好的性能;转换增益为3dB,在50～860MHz的频率范围内增益变化小于0．5dB,IIP3为10dBm,在3．3V单电源下消耗20mA的电流。对实际样片的测试表明电路的混频功能良好。     

一种高线性度混频器设计

高线性度混频器是大动态接收系统的关键器件,其线性度的提高有利于扩展接收系统动态范围。通过对二极管混频器的非线性分析,从理论上推导出增加二极管数量可以提高混频器线性度。基于理论分析结果,采用Ga As p HEMT工艺,设计了一款高线性度双平衡混频器,射频频率0.03~3 GHz,对应本振频率3.95~6.92 GHz,中频输出频率3.92 GHz,输入三阶截点大于25 d Bm,本振到中频、本振到射频的隔离度均大于37 d B,单片面积1.5 mm×1.1 mm。     

高线性度下变频SiGe混频器

MAX19996A是带有片内LO缓冲器的完全集成、2000～3900MHz下变频混频器。其提供完全集成的下变频通道，具有＋24．5dBm（典型值）ⅡP3、8．7dB（典型值）转换增益和9．8dB（典型值）噪声系数。     

针对4G无线基站收发器的低功耗低失真混频器

IDTFll62是一款低功耗、低失真双路2300～2700MHz射频到中频混频器,拥有超线性（＋43dBm）三阶交调截取点（IP30）,可达到优异的互调抑制,是4G无线基站收发器中多载波、多模式蜂窝系统的理想选择。多达0．4dB的改进接收器SNR有利于无线通信运营商扩大覆盖面积和提高用户手机外围的可用数据率。     

一种高线性度低噪声下变频混频器

采用SMIC 0.18 μm RF CMOS工艺,设计了一种高线性度、低噪声下变频混频器。通过分析跨导级电流3阶展开项系数,优化跨导级偏置电压,在跨导级与开关级之间增加谐振频率为射频信号频率的LC并联谐振电路,在提高电路线性度的同时优化了信噪比。后仿真结果表明,在射频频率为1.575 GHz,本振频率为1.571 GHz,中频频率为4 MHz时,本振功率为0 dBm,电压转换增益为19.22 dB,输入3阶交调点为21.93 dBm,单边带噪声系数为11.74 dB。混频器工作电压为1.8 V,功耗为3.66 mW,核心电路版图面积为0.207 5 mm²。     

高线性度的CMOS下变频混频器的设计

采用正交反馈的跨导级设计了一种基于数字电视调谐芯片中的高线性度的下变频混频器,该混频器在3.3V的工作电压下,采用改进的Gilbert单元,使用基于Chartered0.25μm标准CMOS工艺进行流片测试,结果表明该混频器IIP3可达到15dBm,增益达到9dB。     

高线性度双通道下变频混频器

LTC559x系列由4个高动态范围、双通道下变频混频器组成的,涵盖600MHZ～4．5GHz无线基础设施频率范围。LTC5559x双通道混频器系列具有超过26dBm的IIP3（输入3阶截取）、低于10dB的低噪声指数和8．5dB的高转换增益,从而可为MIMO（多输入、     

1.9 GHz高线性度上混频器设计

介绍了采用0.35μm CMOS工艺实现的单边带上变频混频电路。该混频电路可用于低中频直接混频的PCS1900(1 850~1 910 MHz)发射器系统中。电路采用了multi-tanh线性化技术,可以得到较高的线性度。在单电源+3.3 V下,上混频器电流约为6 mA。从上混频电路输出级测得IIP3约8 dBm,IP1dB压缩点约为0 dBm。     

Wireless Mesh Architecture for IP-Based Base Stations

Combining the performance advantages of both Wireless Local Area Network (WLAN) and Ad hoc network, Wireless Mesh Network (WMN) is characterized by large capacity, high rate and wide coverage. It has become an effective means for broadband wireless access and can be applied flexibly in various wireless environments. The wired connections between base stations in traditional cellular mobile communications systems can no longer satisfy the requirements for flexible deployment, low cost, high scalability and good reliability. The wireless Mesh architecture for IP-based base stations is thus introduced as an optional solution to support the flat and simplified next generation mobile communications networks. The key technologies used to support self-organization of IP-based base stations involve several aspects, including on-demand self-organization of base stations, joint radio resource scheduling mechanism, routing, security and network management.     

IP化基站无线Mesh组网构架

无线网状网（WMN）融合了无线局域网（WLAN）和Ad Hoc网络的性能优势,具有容量大、速率高、覆盖范围广等特点,成为宽带无线接入的一种有效手段,可以灵活地应用于多种无线环境。目前,蜂窝移动通信系统中各基站间的有线连接,使得传统的蜂窝移动通信系统难以满足部署方便、成本低廉、高可扩展性、高可靠性等指标。为适应下一代移动通信网络扁平化、简单化的发展趋势,IP化基站的无线Mesh组网架构是可选方案之一。支持IP化基站自组织的关键技术包括按需的基站自组织技术、联合无线资源调度机制、路由技术、安全技术、网络管理技术等。     

无线基站市场上演"双雄会"

● 市场的低迷和增长的停滞使基站设备生产商面临极大的价格和创新压力,基站内部模块接口的开放和标准化趋势不可阻挡;● 由基站制造商自发成立的OBSAI和CPRI两大组织有望使模块生产商、基站制造商和运营商受益;● OBSAI和CPRI两强并存的局面可能使统一之势增添变数,加强合作才是唯一出路;     

蜂窝网络基站无线桥接的研究

介绍了应急场景下蜂窝基站无线桥接应用的需求,从应急场景信号覆盖和网络流量两个情况,比较了WiFi网桥、LTE网桥和UHF网桥的技术优劣,针对UHF无线网桥,基于无线信号传播模型,从理论上分析了链路预算与发射功率需求,并对上海地区地面广播电视频谱分布情况进行了分析,指出地面广播电视的空白频谱可以用于应急场景下蜂窝基站的UHF桥接.     

Positioning of Base Stations in Wireless Sensor Networks

Wireless sensor networks (WSN) have attracted much attention in recent years due to their potential use in many applications such as border protection and combat field surveillance. Given the criticality of such applications, maintaining a dependable operation of the network is a fundamental objective. However, the resource-constrained nature of sensor nodes and the ad hoc formation of the network, often coupled with an unattended deployment, pose non-conventional challenges and motivate the need for special techniques for dependable design and management of WSN. In this article, we highlight the potential of careful positioning of the base station (BS), which acts as a sink node for the collected data, as a viable means for increasing the dependability of WSN. We categorize published work on optimal positioning of BS in WSN. Referring to such work as static positioning, we further introduce dynamic schemes that reposition the BS during the network operation. We show that dynamic BS positioning can be very effective in optimizing the network functional and non-functional performance objectives and in coping with dynamic changes in the environment and available network resources     

基站应用高线性高效率50 V GaN HEMT

报道了针对移动通信基站应用的GaN HEMT的研制。通过采用NiAu势垒,降低器件栅极漏电,从而提高器件击穿电压。同时通过优化V型栅,降低了峰值电场,提高器件击穿电压30%以上。GaN HEMT器件设计采用双场板结构,工艺采用0.5μm栅长,工作电压50V,在2.3~2.7GHz带内峰值输出功率280 W,功率附加效率>64%,线性度-30dBc@PAR=5dB,器件抗失配比(VSWR)至5∶1,器件性能可以满足未来基站多频段多载波应用需要。可靠性试验结果表明,研制的器件在150℃下平均工作寿命(MTTF)>4×10~6 h,满足系统应用需要。     

数字放大器令3G无线网基站成为可能

第三代(3G)无线通信标准,包括W-CDMA、cdma2000、EDGE,正在开始再造移动通信业市场。 鉴于3G无线网被设计为支持使用包协议同时支持话音和宽带数据传输,各基站的功率放大器均必须以更高的效率提供更高的性能。通过采用已包含DSP技术的新型数字放大器,系统设计     

Wireless Location Estimation With the Assistance of Virtual Base Stations

In recent years, wireless location estimation has attracted a significant amount of attention in different areas. Various types of radio signals are applied for the development of location-estimation algorithms. In this paper, the range measurements acquired from the received time-based information are adopted, and the modified least square (LS) method is utilized to process the raw data and to finally locate the target object. Practical issues, such as the nonline-of-sight (NLOS) errors and the geometric dilution of precision (GDOP) effect, are of concern. The NLOS error will cause a large nonnegative bias while measuring the propagation delay, which will lead to an unreliable result for location estimation. On the other hand, a large GDOP value corresponds to a poor geometric topology, which will result in inferior performance by adopting most of the existing location algorithms. The proposed location-estimation algorithms with virtual base stations (VBSs) will both mitigate the influence from the NLOS errors by imposing the geometric constraints and reduce the GDOP effect by incorporating the assisted VBSs. Two iterative schemes are proposed, including the center-of-gravity-based VBS (VBS-CG) and the minimal GDOP-based VBS (VBS-MG) algorithms, to determine the required number and the locations of the assisted VBSs. The proposed VBS algorithms are compared with other existing location-estimation schemes via simulations. The performance of the VBS-MG algorithm is observed to outperform the other schemes, particularly under the environments with larger NLOS errors and poor geometric layouts.