高频课程设计晶体管混频器

通信电子线路课程设计说明书三极管混频器学院：电气与信息工程学院学生姓名：王凯学号：11401340336指导教师：张松华专业：通信工程班级：1103班完成时间：2013.12.181摘要混频器在通信工程和无线电技术中，应用非常广泛，在调制系统中，输入的基带信号都要经过频率的转换变成高频已调信号。在解调过程中，接收的已调高频信号也要经过频率的转换，变成对应的中频信号。特别是在超外差式接收机中，混频器应用较为广泛，如AM广播接收机将已调幅信号535KHZ-一1605KHZ要变成为465KHZ中频信号，电视接收机将已调48．5M一870M的图象信号要变成38MHZ的中频图象信号。移动通信中一次中频和二次中频等。在发射机中，为了提高发射频率的稳定度，采用多级式发射机。用一个频率较低石英晶体振荡器做为主振荡器，产生一个频率非常稳定的主振荡信号，然后经过频率的加、减、乘、除运算变换成射频，所以必须使用混频电路，又如电视差转机收发频道的转换，卫星通讯中上行、下行频率的变换等，都必须采用混频器。由此可见，混频电路是应用电子技术和无线电专业必须掌握的关键电路。本次课程设计采用三级管混频器具有电路简单，变频增益高的特点，采用9014三极管，接受LC高频信号和本振信号对两信号进行取差频，使用滑动变阻器改变静态工作点，使其工作在非线性工作区域，使用中周进行选频。由于晶体管的非线性特性，两个信号混合后会产生fL+fC、fL－fC频率的信号，然后通过中频滤波网络，得出所需要的中频信号。关键词：混频器三极管选频2AbstractKindsofinformationisveryimportanttohumanlife,sopeoplearealwayslookingforfastwaytocommunicateoverdistance,totransferortoexchangeinformation.Modernlongdistancecommunicationtechnologywasinventedinmidof18thcenturythankstotheinventionofradiotechnology.Sincethen,thistechnologywaswelldevelopedandmanynewmethodscameout.FromMorsecodetosatellite,moderncommunicationisplayingmoreandmoreimportantrole.Asakeypartofradiotechnology–mixing,e.g.transistormixer,diodemixerandFETmixer,etc.arebroadlyusedindifferentsystem，toshiftfrequency.Thecurriculumdesignusingthreetubemixerhasasimplecircuit,highfrequencygaincharacteristics,uses9014transistors,high-frequencysignalsandtheacceptanceofLCoscillatorsignalfortwototakethedifferencefrequencysignal,usingaslidingrheostattochangethequiescentoperatingpoint,toworkinthenonlinearoperatingregion,theuseoffrequency-selectiveweeks.Sincethenonlinearcharacteristicofthetransistor,themixingoftwosignalsproducesfL+fC,thefrequencysignalfL-fC,thefrequencyfilterandthenthroughthenetwork,therequiredintermediatefrequencysignalobtained.Keyword:mixer;Transistor;frequency;3目录摘要..............................................................................................................................................1Abstract.............................................................................................................................................2一设计要求及指标.....................................................................................................................41.1设计目标..........................................................................................................................41.2设计要求和技术指标......................................................................................................41.3混频电路的基本原理......................................................................................................4二三极管混频器的仿真分析.....................................................................................................52.1仿真分析............................................................................................................................52.1.1混频电路分析.......................................................................................................52.1.2总体方案介绍.......................................................................................................62.1.3工作原理说明.......................................................................................................72.2仿真结果.................................................................................................................11三仿真结果分析、干扰及解决办法、设计总结.......................................................................123.1仿真结果分析..................................................................................................................123.2干扰及解决办法..............................................................................................................123.3设计总结..........................................................................................................................12参考文献.........................................................................................................................................13致谢..............................................................................................................................................14附录一：.........................................................................................................................................15三极管混频器仿真电路：.....................................................................................................15PCB图....................................................................................................................................16实物图.....................................................................................................................................16元器件清单.............................................................................................................................174一设计要求及指标1.1设计目标设计一个三极管混频器。1.2设计要求和技术指标设计一个三极管混频器，要求中心频率为10MHz,本振频率为16.455MHz，混频输出为6.465MHz的正弦波。1.3混频电路的基本原理混频电路是一种频率变换电路，是时变参量线性电路的一种典型应用。如一个振幅较大的振荡电压（使器件跨导随此频率的电压作周期变化）与幅度较小的外来信号同时加到作为时变参量线性电路的器件上，则输出端可取得此二性号的差频或和频，完成变频作用。他的功能是将已调波好的载波频率变换成固定的中频载频率。而保持其调制规律不变，也就是说它是一个线性频率谱搬电路，对于调幅波、调频波或调相波通过变频电路后仍然是调幅波，调频波或调相波。只是其载波频率变化了，其调制规律是不变的。