TI宽带直流放大器

TI大赛12010年江苏省TI杯电子设计竞赛论文学校：南京信息职业技术学院学生：张加跃沙龙居以祥指导老师：李立早俞金强题目：宽带放大器(A题)TI大赛2宽带直流放大器摘要：本作品基于宽带放大器的设计，由前级放大模块，增益控制模块，后级功率放大模块，A/D转换模块，液晶显示模块和电源模块组成。前级放大由电压反馈放大器OPA842，OPA820放大输入信号，输出放大指定倍数的电压。再由以电流反馈放大器THS3001为核心的第二级增益控制模块进行放大。后级功率放大模块由电流反馈放大器THS3091来实现，TPS61087DRC为其提供±12V的电压。其中后两极采用运放并联设计，此设计是为了增大驱动电流，增强带负载能力。本设计采用三级放大，增强整个电路的驱动能力，进行合理的级联和阻抗匹配，加入后级驱动，全面提高了增益带宽积和输出电压幅度。应用单片机和数字处理技术，使得结果更加可靠有效。电路增加去耦，滤波等措施，以减少放大器的噪声及抑制自激振荡。经实际电路检测，本设计符合题目的设计要求。关键词：宽带放大器前级增益Abstract:Thisworkisbasedonthedesign,broadbandamplifierbyformeramplifiermodule,andgaincontrolmodule,thepoweramplifiermodule,A/Dconversionmodule,LCDmoduleandpowersupplymodule.FormeramplifierOPA842byvoltagefeedbackamplifieramplification,OPA820inputsignal,theoutputvoltageamplifierdesignatedmultiples.AgainincurrentfeedbackamplifierbyTHS3001asthecoreofthesecondarygaincontrolmoduleamplification.ThepoweramplifiermoduleTHS3091bycurrentfeedbackamplifier.Afterusingop-ampofpolarizationparalleldesign,thedesignistoincreaseandenhancebeltdrivecurrentloadcapacity.ThisdesignUSES2amplifiercircuit,enhancetheabilityofdriving,reasonablelevelandimpedancematching,tojointhedriver,increasetheoverallgainbandwidthandoutputvoltageamplitude.Thechipanddigitalprocessingtechnology,theresultismorereliableandeffective.Decouplingfiltering,increasedcircuit,inordertoreducethenoiseamplifierandself-excitedoscillation.Thepracticalcircuitdesign,thedesignofthesubject.Keywords:broadbandformergainTI大赛3目录一．方案论证与设计.......................................................................................................................41.1方案设计与比较................................................................................................................41.1.1前级放大部分........................................................................................................41.1.2功率输出部分........................................................................................................41.1.3系统电源................................................................................................................41.2理论分析与计算.................................................................................................................41.2.1带宽增益积............................................................................................................41.2.2电路直流零点漂移................................................................................................51.2.3放大器的稳定性....................................................................................................5二．硬件电路设计...........................................................................................................................52.1系统框图.............................................................................................................................52.2主要模块电路.....................................................................................................................62.2.1前级放大模块........................................................................................................62.2.2增益控制模块........................................................................................................62.2.3后级功率放大........................................................................................................82.2.4检波模块................................................................................................................82.2.5电源模块................................................................................................................9三．软件设计.................................................................................................................................10四．系统测试和数据分析.............................................................................................................104.1测试仪器...........................................................................................................................104.2放大器的增益测试...........................................................................................................104.3数据分析...........................................................................................................................11五．结论与系统改进.....................................................................................................................11六．附录.........................................................................................................................................11参考文献.................................................................................................................................11电源部分电路图.....................................................................................................................12TI大赛4一．方案论证与设计1.1方案设计与比较1.1.1前级放大部分方案一：采用两级程控级联构成的前级放大电路，对不同大小的输入信号进行前级放大，此电路虽然能较大范围的实现程控增益，但电路调试困难，控制复杂，对PCB的要求较高。所以未采用此方案。方案二：采用多级放大的级联实现增益的放大。每一级设置不同的增益档位，对不同大小的输入信号进行放大，最终达到输出电压峰峰值10V的要求。此方案简单易实现，且分成2级，每级可单独测试，使得调试简单化，有问题容易查找。在第二级中也有电流放大，增加驱动。电路成本也低，所以最终采用第二种方案。1.1.2功率输出部分方案一：采用高频三极管等分立元件手工搭建。此方案成本较低，元器件易购置，但是设计调试难度大，尤其是短时间内手工制作难以保