CDMA2000基站收发信机射频前端分析与设计

【作者】 孙果英；

【导师】 鲍景富；

【作者基本信息】 电子科技大学 ， 电路与系统， 2009， 硕士

【摘要】 自20世纪90年代以来,无线通信在世界范围内有了突飞猛进的发展。3G网络正在如火如荼的建设中,中国也已经发放3G牌照。3G主要采用CDMA(码分多址)技术,其主流标准为TD-SCDMA,WCDMA和CDMA2000。由于CDMA2000能够实现真正意义上的从2G(IS-95)到3G的平滑过渡,并且具有技术成熟、成本低、商用化快、数据和语音吞吐量最高等优点,是目前最具竞争力的3G标准,对它的研究是一个非常热门的课题。基站收发信机前端的性能直接决定了空口的指标,结合3GPP2对基站性能的最低要求,设计性能优越的基站收发信机前端是本文的重点工作。本文从时域角度分析了影响平衡式低噪放性能的因素,得出了两支路的平衡程度是决定平衡式低噪放性能的关键因素。利用最新的器件设计了本振模块和射频收发链路。本文从理论分析、数学推导、图形示意、工程实现等角度对以下几个方面做了详细论述。1.基站收发信机前端关键电路(如本振、低噪放、ADC、采样时钟等)的指标与CDMA2000系统指标的关系。2.平衡式低噪放的理论分析、仿真和电路实现;本振源模块的理论分析和电路实现。3.根据3GPP2的要求,分析基站收发信机的空口指标,包括发射机的发射功率、发射杂散、EVM,ACPR,MAX IT以及接收机灵敏度、动态范围、单音去敏等指标与射频收发链路各项射频指标的关系。收发信机前端链路指标分配,包括增益、噪声系数、1dB压缩点、杂散、IP3等指标。5.在整机环境下对收发信机射频前端进行测试,并对测试结果进行判断和分析。通过严格的指标分析、方案论证、仿真及器件选择,设计实现了性能优越、成本低、PCB兼容CDMA各个频段的基站收发前端。测试结果优于3GPP2的最低要求。更多还原

【Abstract】 Wireless communication plays an important role in modern communication system. It gets a rapid development from 1980s.The third generation wireless communication network has been used worldwide.The standards of 3^rd generation are CDMA2000, WCDMA and TD-SCDMA.They all base on CDMA（Code Division Multiple Access） technology.CDMA2000 is totally compatible with IS-95.So CDMA2000 has the biggest competitive advantage.The transceiver is one of the most important parts in base station system.The performance of the transceiver decides the air interface specifications directly.The key item of this work is design excellent transceiver RF front end according to recommended minimum performance standards by 3GPP2.We give an analysis of balanced low noise amplifier（LNA） which has good voltage standing wave ratio （VSWR） performance,higher linearity and good stability.A mathematic model of balanced LNA has been setup and an analysis of gain,noise figure（NF） and VSWR based on it is presented.According to analysis in time domain and simulation in advance deign system（ADS）,the unbalance of gain,NF and VSWR will affect the performance of the balanced LNA module.It gets a zero reflection on condition that its two branches totally balanced.The primary work of this paper includes theory analysis,simulation,circuit design, PCB layout and system testing.The content architecture of this paper is shown as follows:1.Analysis of key devices of the transceiver,such as LNA,LO（local oscillator）, ADC,sampling clock and so on.The relationship of specifications between key devices and CDMA2000 system are proposed too.2.Analysis and design of balanced LNA and LO module.A detailed analysis, simulation and design steps of balanced LNA and LO are proposed.3.Analysis and design of tranceiver RF chains.The specifications of transceiver meet the standards of 3GPP2,such as output power,EVM,frequency stability,emission spurious,ACPR,sensitivity,and single-tone desensization.The design methods and chain structure are proposed.4.The testing methods and results of LNA,LO,and transceiver are introduced in chapter 5.Conclusions are also proposed in this chapter.Acoording to precise theory analysis,simulation and design,we design a transceiver which has excellent performance,and can be used in all CDMA band classes. The testing results indicate the design is coincident to the standars of 3GPP2.更多还原