新型高效射频预失真器的分析与设计

设计了一种简单而有效的射频预失真器。通过理论分析指出,为了灵活有效 地产生期望的预失真特性,预失真器应包含至少两个独立调节变量。以此为依据,提出了一 个由二极管和分别与之串联和并联的电阻和电容组成的预失真电路,将其应用于工作在1. 9 GHz、输出功率为43 dBm的功放,三阶互调失真系数（IMD3）改善10 dBc。该 预失真器不仅对非线性改善效果明显,与同类预失真电路相比,还具有结构简单、体积小 、成本低的优点。     

RLS算法在基带预失真系统中的应用

传统的最小二乘（LS）类预失真算法运算量大,且不能跟踪功放的变化特性。推导了基于 递归最小二乘（RLS） 算法和间接学习型结构的自适应基带预失真算法,并仿真和分析了算法的性能,结果显示该 算法与传统的LS类预失真算法对系统功放非线性改善的效果相当。为了进一步验证算法的有 效性,设计和构建了具有预失真功能的短波发射系统。硬件测试结果表明,该算法对功放输 出的双音信号的三阶互调改善量达25 dB,所有互调分量均低于-53 dB。     

毫米波线性化固态功放的研制

研制了工作于Ka频段的10 W线性化固态功放。采用预失真技 术的线性化单元主要由一个肖特基二极管和一个电容并联构成,具有增益扩展和相位延迟的 特性, 并且其增益和相位特性具有可调性。将其应用于工作频率为30 GHz、输出功率为10 W 的功放,双音激励信号频率间隔为5 MHz,三阶互调（IMD3）可以改善15 dBc。     

功率放大器的自适应预失真线性化技术

重点介绍了几种主要的功率放大器的自适应预失真技术,包括基带预失真、中频预失真及射频预失真技术,以及几种自适应预失真工作函数的产生方法,并利用多项式产生工作函数的方法对功率放大器进行预失真调整,使其线性度得到明显改善。     

一种新型C频段高效率移相GaN功率放大器

研制了一种性能优良的全固态C频段高效率移相氮化镓（GaN）功率放大器模块。介绍了该功 放模块设计方案及工作原理,并给出了该功放模块技术参数实验测试结果。该模块 输出功率30 W,带宽10 MHz,带有6位移相功能,具有C频段高频率、固态、小型化 、高效率、高功率密度、高击穿电压特性,是一种目前国内外尚无类似集成设计的最新高 性能氮化镓（GaN）功率放大器模块。因其功放模块输出末级采用了美国Cree公司第三代宽 禁带GaN功放管优化设计,实现了固态C频段高效率功率输出。     

宽带卫星功率放大器失真补偿技术研究进展及应用

针对宽带卫星通信系统中高功率放大器的记忆非线性失真问题,对不同补偿技术进行 了综述,重点研究了预失真的学习结构、数据预失真、信号预失真、时频域预失真和自适应 均衡等补偿技术并对它们进行了相应的优缺点比较,最后提出了宽带卫星功放实际应用环境 下的4种补偿方案,为我国宽带卫星功放失真补偿研究提供理论参考。     

一种新型宽频带多频微带天线设计

目前,同时适用于蓝牙、射频识别、全球微波无线互联网和无线局域网这几大主流物联网通信技术标准的多频天线设计较少,为此,提出了一种新的小型化宽频带多频微带天线。该微带天线主要由一个矩形环、一个开口六边形环、三条矩形带以及缺陷地组成,可同时工作在蓝牙、射频识别、全球微波无线互联网和无线局域网的通信频段上。天线谐振频率分别为2.47 GHz、3.48 GHz和5.55 GHz,相应带宽为0.11 GHz(2.38～2.49 GHz)、0.86 GHz(3.19～4.05 GHz)和1.11 GHz(4.95～6. 06 GHz),增益最高达到5.75 dBi。实测结果显示,该天线在工作频段具有很好的辐射特性和增益,适用于当前应用的无线通信系统。     

新型三等分Wilkinson功分器在高效率功放中的应用

针对一种新型的三路Doherty功率放大器,为满足其对称结构要求,在传统对称结 构二等分功分器基础上,结合三路Doherty功放电路尺寸,通过理论计算和采用ADS软件仿真 的方法设计了对称结构三等分Wilkinson功分器。其尺寸为19 mm×11 mm,在2.11 ～2.17 GHz内,插入损耗小于0.4 dB,输出端口隔离度大于16 dB,端口回波 损耗大于13 dB。在适应三路Doherty功放对称结构的前提下,功分器性能指标满足功放 电路三路相位一致性设计要求,提高了放大器工作效率,测试结果显示饱和点工作效率高于 两路Doherty功率放大器。     

放大器估计器的查表法自适应预失真器设计

非线性功放特性随温度,供电电压等因素的变化而改变,为保证其稳定工作,预失 真系统的自适应性能就显得非常重要。当前的自适应预失真算法每次都对其参数进行更新, 计算量很大。针对这个问题提出了一种放大估计器的查表法自适应预失真算法,将查表法和 放大器估计器法结合在一起,以误码率为指标在系统允许的误差范围内可以大大减少参数的 迭代次数。同时针对不同的输入回退,可以选择采用不同的预失真算法,从而使其更加接近 功放特性,进一步减少迭代次数。     

L频段低谐波失真功率放大器的设计

针对L频段低谐波失真功率放大器的设计,进行线性与非线性电路分析仿真和电路的优化设计。从理论上分析了甲乙类功率放大器的谐波失真特性,通过采用具有抑制谐波特性的输出匹配电路以降低功放产生的谐波失真。测试得到电路的关键技术指标为:工作频率范围1 390~1 510MHz,增益35 dB,1 dB压缩点33 dBm,并获得了满意的谐波抑制指标,在1 480 MHz、输出功率33dBm时,二、三次谐波分别为-70 dBc和-63 dBc。结果表明在功放设计中,优化设计输出匹配电路可以有效抑制功放的谐波失真。     

Public Financial Expenditure——A Reflection of the Livelihood Improvement

In recent years.China's public finance put social construction high on the agenda and attaches more importance on livelihood insurance and improvement.The 2003-2007 public financial expenditure reflects a fact that the government isputting more emphasis on livelihood andissues concerning the people.     

Voices from the MPC and CPPCC

"Crucial for economic growth.energy utilization has its role in all economic sectors and every aspect of people's daily life.Now we are in dire need of a new profession,namely energy manager.We not only need to have passion and responsibility,but also a scientific approach to conserve energy and cut emissions.APpropriate legislation should be in place.and a special profession should be introduced to ensure the implementation of these laws and regulations."     

Slowdown Trade Surplus Growth

According to Ma Kai＇s economic planning report submitted to the NPC session on March 5th,（Ma Kai is the Minister in charge of the National Development and Reform Commission）,the government has listed the slowdown in trade surplus growth and the steady expansion of external investment as major tasks for 2008.     

Ouyang Riping： A Hero Besides Entrepreneur

A bout fifty years ago. a baby＇s cry broke the sky of quietness, in a small and beautiful town of Hunan province, which surroundcd by green hills and clear water. Though his .birth brought his family great happiness and hope just as any new life, nobody knew that the little boy would get great achievement when he grow up. even start his business oversea, and earn international honor. Let＇s share with you the entrepreneur Ouyang Riping＇s story, which may insights thcsc people who want to succeed and complete oneself in favorite condition or adversity rather leave things to so-called fate.     

Belarus, A Chinese Fort in Europe

＂In recent years, we＇ve found increasing interest from Chinese investors in the Belarus economy. Please let China know, Belarus is always ready to be a true friend to China. We have built a fort in Europe for China,＂ the President of Belarus, Alexander Lukashenko told Zhou Xiaochuan, President of the Bank of China, during his visit to the capital of Minsk, on January 8th, he expressed his high praise and firm confidence in the development of Sino-Belarusian relations.     

What＇s Behind Spring Festival？

Similar to what the Christmas Day means for the westerners,the Spring Festival is the most important celebration for Chinese people.This big event according to Chinese traditional lunar calendar relaxes and pleases the whole country as the happiest gathering time of the year.National-wide crusade for going back home,too-difficult-to-get train tickets,generous family-going-out shopping,Miaohui laundering,New Year Eve reunion dinner,visiting friends and relatives,watching annual TV gala......each piece of clue reminds us of the smell of Chinese Spring Festival.     

KEY WDRDS for Foreign Investment in China

FDI(Foreign Direct Investment),a component of a country's national financlal accounts,is investment of foreign assets into domestic structures,equipment,and organizations.It does not include foreign investment into the stock markets,concession and subcontract.FDI iS thought to be more useful to a country than investments in the equity of its companies because equity investments are potentially "hot money"which can leave at the first sign of trouble,whereas FDI is durable and generally useful whether things go well or badly.     

Brown＇s Blossom in Britain-China

The overall strategic relationship between U.K. and China is ＂better than ever＂, China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit.     

Consumption, New Protagonist in 2007 GDP

Not long ago, the National Bureau of Statistics released its 2007 Macro Economy Index. Social consumption retail sales reached RMB 8.9 billion, increased by 16.8 percent over the previous year, or 3.1 percentage points higher; the whole investment in social fixed assets was valued RMB 13.7 billion, a year-on-year increase of 24.8 percent, that is 0.9 percentage points higher; and trade surplus amounted to RMB 24.7 billion, rising by 47.7 percent compared with the same period last year, 26.3 percentage points falling over the increasing speed last year. According to preliminary estimates, GDP for the year was RMB 24.67 trillion, up by 11.4 percent from the previous year,