In the part of modulation and demodulation , we analyzed the principles of harmonic mixer , detectors , power dividers / combiners and branch - line couplers 对调制/解调器射频电路部分，包括亚谐波混频器、检波器、功率分配/合成器和分支线耦合器基本原理进行了分析。
So the rf circuit is the hinge of the signal chain , and many key targets of the whole receiver , such as noise figure , sensitivity , are determined by it 因此,射频电路是整个信号接收链路中的一个枢纽,整个接收机的噪声系数、灵敏度等关键指标也都主要由该电路决定。
These analysis and results are important and useful for the design of integrated inductors . 5 . special issues to implement the rf integrated circuits are discussed 我们提出的这种新型的集成电感，结构上不同于常规平面螺旋型集成电感，为射频电路设计者设计集成电感时提供了一种选择。
The test results show that the design method and circuits that are presented in this thesis are feasible and it is possible to accomplish the design of rfic with standard digital cmos technology 测试结果表明,本文提出的设计方式和电路有其可行性。用标准的数字cmos工艺来完成射频电路的设计是可能的。
Different manner has different needs of the rf circuit . a reasonable choice may greatly reduces the complexity of the signal processing in the back - end , but it has not been generally analyzed in the former references 不同的信号输出方式对射频电路有着不同的要求,合理的选择信号输出方式可以大幅度降低后端信号处理的复杂度。
Low noise amplifier using fet is adopted in the rf block of smart antenna both at 3 . 95ghz and at 1 . 9ghz . in the design process of lna , the author applies genetic algorithm in the optimization of gain and noise figure 两套射频电路的低噪声放大器电路均采用了两级场效应管放大，在其增益及噪声的优化过程中采用了遗传算法这一全局搜索性能较好的数值算法。
The author ' s main research work is focused on the design of lna , mixer and dro in smart antenna at 3 . 95ghz , and lna in smart antenna at 1 . 9ghz . the principles and design process of these schematics are analyzed 本文的主要工作体现在3 . 95ghz智能天线射频电路中低噪声放大器、单平衡混频器、介质振荡器的设计，以及1 . 9ghz智能天线射频中低噪声放大器的设计。
And , the rf - circuit design methods are endlessly discovered to suit for the application of uwb . especially , the designs of the antenna module that is the output entrance to uwb rf systems , which have already become hotspot research subject 也正在不断寻找适用于uwb应用的射频电路设计方法。其中,作为uwb系统射频端出入口的天线模块的设计已经成为目前研究的热点。
Because of the self - control module , the linearization power amplifier system can work steadily in defiance of the changing of temperature , time , input power etc . it makes the system more practicably and expends the use of linearization system 由于加入自适应控制模块,射频电路不受温度、时漂、输入功率等的影响,可始终处于较佳工作状态,这使得整个放大系统更为实用,也更具有拓展价值。
The portable instrument is the key in this system because it not only communicates with the point but also carries serial communication through rs232c . so rf401 is used to realize rfid ( radio frequency identification ) on the basis of the specialty of this system 3 、根据该系统工作特点选用rf401实现无线射频电路，对手持巡检仪采用无线射频技术与巡检点进行通讯，通过rs232c与pc机进行串行通讯。
