MC1648两种改进型VCO的压控特性和频率稳定性研究

本文对2种改进型VCO的压控特性和频率稳定性进行了分析，并给出实际测量结果。结果表明,两VCO在变容管允许承受的整个反偏压范围内，压控特性具有较好的线性，频稳度达10^-4-10^-5级，大大优于一般频率固定的LC振荡器，所以适合于性能要求较高的场合使用。     

无线电高度表微波集成前端

研制的4.3GHz无线电高度表微波集成前端已得到实际应用,它代替了整机原用的振荡-放大一倍频方案,提高了效率、减小了体积.微波集成前端采用了高线性度FET压控振荡器作发射源,采用高隔离度的单桥路不等负载三分贝混合环混频器.在-40°～70℃的环境温度范围内发射功率大于150mW,压控带宽123MHz,线性度小于3%,接收机噪声系数小予8dB.     

一种新型的四阶低抖动带双控制环路CMOS锁相环

设计了一种四阶低抖动带双控制环路压控振荡器的锁相环（PLL）。该锁相环在恒定的反馈参数下，压控振荡器压频增益几近恒定。锁相环的所有部件都设计在同一芯片上，电路设计基于0．35μmCMOS工艺。HSPICE仿真结果显示，所设计的锁相环路具有很好的抗噪声性能，工作在800MHz频率范围内，整个相位抖动小于4ps rms。     

通信用压控晶体振荡器研究

随着电子信息技术在不断的革新，石英晶体振荡器在各个领域中的应用越来越广泛，它在通讯、导航、雷达以及频标信号源的整机和设备中具体的应用，本文主要研究了压控晶体振荡器在移动通信技术中的应用，在使用和发展的过程中对移动通讯技术提出了新的要求：逐渐的朝着高频化、小型化以及低功耗的方向发展，因此本文对这些新的要求进行了重点的研究，推动了移动通信行业的进一步发展。     

一种同播发射机的基准频率源设计

根据同播系统对同播发射机的要求,提出了一种利用GPS秒时钟修正晶体振荡器频率 漂移,实现高稳定度基准频率源的方法。该方法根据数字锁相原理,采用CPLD作数字鉴相器 ,通过测量GPS秒时钟与压控晶体振荡器(VCXO)时钟间的相位差,并将其转变为直流电压控 制晶振频率,取得了频率稳定度优于2×10-9的成果,已成功应用于同播发射机中。     

一种S频段微带压控振荡器的设计与实现

在对压控振荡器设计原理进行了分析的基础上,介绍了压控振荡器的设计所遵循的一般原则,详细阐述了一种基于ADS软件的S频段微带压控振荡器的设计和实现过程。经过调试验证,实验结果与用ADS软件仿真的结果一致,这种方法对从事频率源研制具有一定的理论指导意义和实际应用价值。     

压控振荡器在射频通信电路中的应用讨论

目前，现代雷达系统和现代通信系统得到了发展，在此情况下射频电路就需要将稳定的谐波震荡建立在特定的载波频率点上，这样就可以给混频和调制打下一定的基础。为了达到压控振荡器的宽调频，笔者设计了一个负阻LC压控振荡器，该压控振荡器的震荡频率在1.14~1.18GHz范围中，而频率范围达到了40MHz。此外，将射极跟随器配置在电路中，将其看做是buffer，这样做的目的是降低甚至避免外部电路对压控振荡器产生影响，最终达到级间隔离以及阻抗变换的双重作用。     

国有企业“两金”压控管理解析

国家正提倡企业要在新经济常态下实现企业的产业升级和转型,国有制造企业存货周转率、应收账款周转率等各项经济指标有逐步降低的迹象,导致企业资产负债率在逐步提升,"两金"占比过高将直接影响国有企业业务扩展及经济收益成效。近来年,国务院、省、市各级国资委开始要求国有企业不断提高企业财务管理能力,通过压控"两金"提升其综合发展实力。本文通过解析国有制造企业"两金"压控管理方略,以期助力国有企业稳健发展。     

900 MHz压控振荡器设计

采用集总元件变容二极管和超高频三极管设计900 MHz压控振荡器,根据ADS2006A软件仿真 确定了压控振荡器的电路参数,并对相关指标如相位噪声、调谐带宽、稳定系数、输出功率 和谐波电平等进行了仿真,通过调整电路参数,优化电路结构,实现了工作频率为1 GHz、 调谐带宽为90 MHz的压控振荡器,其相位噪声在偏移中心频率10 kHz处为-105 dBc/Hz,在1 00 kHz处为-120 dBc/Hz,该设计大大降低了系统成本。     

微带压控振荡器设计与仿真

介绍了S波段微带压控振荡器的设计方法,并使用微波仿真软件Serenade8.5对振荡器进行仿真分析,给出了仿真和实际电路的结果。     

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.     

Sinosteel：Extraordinary Moves in Industry Chess

Among the Fortune 500 firms,more and more images from China emerge out.On the 2008 list,Sinosteel Corporation,a landmark group of China industries quietly squeezes into the candidate line.As the largest steel service ＆ trade enterprise,its sales reached at RMB 111.24 billion,with a year-on-year increase of 83.03 percent,and the profit grew by 180.03 percent.On the Sinosteel 2008 Work Meeting,the president Huang Tianwen uttered,＂In the coming year,we will work for US$20 billion sales,and look forward to getting a position in Fortune 500 firms for ourselves.＂     

Walk Through Unusual Five Years—— An Exhibitor＇s Canton Fair Course

When the 103rd Canton Fair is approaching, an old friend of Canton Fair, Li Ying from Jiangsu prov-ince recollected his past five years＇ experiences to the grand trade meeting. Each year is special, with some unforgettable memories colored by the year.     

Jean-Pierre Duprieu： Willing to Be A Legate of Sino-French Business

Estaing, former French president, Valery Giscard d＇Estaing attended Sino-French Economic Seminar held in Shanghai in early April and said that the world center has shifted from the west to the east with many European and US companies entering into Asia, and China has the ability to play an important role in the world stage. Estaing, naming himself＂French Confucian＂, then said in Chinese that a cook-group includes 10 people in ancient Chinese soldier system and the cook is in charge of cooking for them. And people who belong to the same cook are actually ＂Partners＂.     

China''''s Stock Market Wave

The annual meeting of the World Economy Forum was held in Davos,a little town in Switzerland,on January 23rd to the 27th this year,with the theme"the Power fo Collaborative Innovation",over 2500 celebrates from ture political and cconomic circles of more than 80 countries and challengred logether to talk about the future of the global economy in 2008,A Forum for the problems and challenges that face whole world,some of the keywords which drew attention during the event were:the U.S.subprime mortgage crisis,soaring energy prices,the economic slowdown in the U.S.ermerging economic bodies,authority funds and the general unpredictable nature of the global economy.     

Trade Promotion from Neighborhood

If you are considering to trade with companies in Japan or expanding your .business to Japan, we are ready to help from the very beginning.＂ You will find this greeting at the first sight on the Chinese website of Japan External Trade Organization （JETRO）. JETRO has committed itself in delivering highly efficient and quality services to meet the demand of internal and external customs including Japanese companies, hence winning a good reputation in the international trade arena. In recent years, with its priority in advancing business cooperation in South and East Asia, JETRO has made great achievement in promoting trade between China and Japan. Therefore, China＇s Foreign Trade interviewed Mr. Yoichi Maine, Deputy Director General of JETRO BEIJING.     

Auto Parts Market Potential Coming into Surface

Looking at the increasingly fierce competition in the world auto market. global automobile manufacturing industry, taking Europe, the U.S. and Japan as representatives, is gradually forming a new type of relationship, mutual cooperation between whole vehicle and parts manufacturers. We can clearly see that auto parts manufacturers have become independent from the whole vehicle manufacturing companies, which means that the former structure of auto industry has greatly changed, and a new relationship,     

China's Auto Industry Steps Forward

Last year,the volume of China's auto trade reached US$66.878 bil- lion,of which imports accounted for US$25.982 billion,a year-on- year increase of 24.45 percent;while ex- ports totaled US$40.896 billion,growing by 45.31 percent.The China Association of Automobile Manufacturers(CAAM) predicts that the number of autos sold in 2008 will break the 1 million barrier for the first time in history,representing an increase of about 20 percent.     

Domino Effect on Electricity and Coal Prices

In the middle of last December, the key purchase contracts for coal used in power generation in 2008 were signed, reflecting a demand for more than 1.085 billion tons. It is important to note that the country＇s five biggest power producers, China Huaneng Group, China Guodian Corporation, China Power Investment Corporation, China Huadian Corporation and China Datang Corporation, had settled on the prices on their purchase contracts, and they are expected to consume 290 million tons of coal for generating electricity,