(第4组)电压控制增益可变放大器设计(VGA)设计(DOC).doc

题目:电压控制增益可变放大器设计（VGA）设计216第四组摘要:基于压控增益放大器VCA822，设计一个能够对频率大于15MHz，幅值小于1V的信号进行调理的程控增益放大器。该放大器增益17~58dB可调，具有自动增益控制的功能。放大器的输出端用宽带运放AD811和分立元件搭建的推挽电路，加强该放大器的驱动负载的能力。关键词：宽带放大器；VCA822；自动增益控制；推挽电路Abstract:UsingFPGAascontrolcore,anewmethodofdesigningaprogrammablegainamplifierwhichcanhandlewiththesignalthathasthefrequencymorethen15MHz,andtheamplitudelessthen1Vbyusingvolt-controllinggainamplifierVCA822ispresentedasfollowing.Theamplifiercanbemodulatedfrom10dBto58dB,withthefunctionofautomaticallycontrollinggain.Theoutputsideofthisamplifieradoptsthepush-pullcircuitconstructedbywidebandamplifierAD811anddiscretecomponents,andenforcesitsabilityofdrivingloads.Keywords:widebandamplifier;VCA822;controlofgain;push-pullcircuit目录TOC\o"1-2"\h\z\uHYPERLINK\l"_Toc363027128"1、系统方案比较与设计PAGEREF_Toc363027128\h3HYPERLINK\l"_Toc363027129"1.1总体方案论证PAGEREF_Toc363027129\h3HYPERLINK\l"_Toc363027130"1.2主放大器选择PAGEREF_Toc363027130\h3HYPERLINK\l"_Toc363027131"1.3中间放大级方案论证PAGEREF_Toc363027131\h3HYPERLINK\l"_Toc363027132"1.4末级功率放大器方案论证PAGEREF_Toc363027132\h4HYPERLINK\l"_Toc363027133"2、理论分析与计算PAGEREF_Toc363027133\h5HYPERLINK\l"_Toc363027134"2.1带宽增益积分析PAGEREF_Toc363027134\h5HYPERLINK\l"_Toc363027135"2.2输出电压幅值PAGEREF_Toc363027135\h5HYPERLINK\l"_Toc363027136"2.3放大器稳定性分析PAGEREF_Toc363027136\h5HYPERLINK\l"_Toc363027137"3、单元电路设计PAGEREF_Toc363027137\h5HYPERLINK\l"_Toc363027138"3.1前级缓冲电路PAGEREF_Toc363027138\h5HYPERLINK\l"_Toc363027139"3.2增益可调的中间放大级PAGEREF_Toc363027139\h6HYPERLINK\l"_Toc363027140"3.3末级功率放大PAGEREF_Toc363027140\h7HYPERLINK\l"_Toc363027141"4、系统测试PAGEREF_Toc363027141\h7HYPERLINK\l"_Toc363027142"3.1测试方法PAGEREF_Toc363027142\h7HYPERLINK\l"_Toc363027143"