模电助教版第4章 负反馈应用基础1

第四章负反馈应用基础P3514.1反馈基本概念1.何为“反馈”?XsFARL‘Feedback’“前馈”?2.框图XsFARL输入信号源(电压源,电流源)基本放大器输出信号(电压,电流)负载反馈网络综合反馈信号净输入信号反馈放大器＋XfXdXoAfXsFARL2.框图XsFARL输入信号源(电压源,电流源)基本放大器输出信号(电压,电流)负载反馈网络综合反馈信号净输入信号反馈放大器＋XfXdXoAfXsFARL比较偏差信号误差信号2.框图XsFARL输入信号源(电压源,电流源)基本放大器输出信号(电压,电流)负载反馈网络综合反馈信号净输入信号反馈放大器＋XfXdXoAfXsFARL闭环放大器2.框图XsFARL输入信号源(电压源,电流源)基本放大器输出信号(电压,电流)负载反馈网络综合反馈信号净输入信号反馈放大器＋XfXdXoAf单向化传输条件信号的两种流向:正向传输：输入输出反向传输：输出输入—开环—闭环闭环放大器在输出端取样，在输入端求和，并承担信号的变换作用。3.定义XsFARL＋XfXdXoAf输入信号源(电压源,电流源)基本放大器输出信号(电压,电流)负载反馈网络综合反馈信号净输入信号反馈放大器Xd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度反馈系数反馈增益回归比闭环放大器闭环放大器3.定义XsFARL＋XfXdXoAf输入信号源(电压源,电流源)基本放大器输出信号(电压,电流)负载反馈网络综合反馈信号净输入信号反馈放大器Xd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度FAAXAFXXAXXXXXAdddfdosof1)(反馈系数反馈增益回归比4.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度FAXAFXXXXXXXdddfddsd11)(FAAXAFXXAXXXXXAdddfdosof1)(FAXXsd11反馈系数反馈增益回归比4.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度FAXAFXXXXXXXdddfddsd11)(FAXXsd11FAXXsd11反馈系数反馈增益回归比4.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度FAXXsd11①负反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|②深度负反馈:|1＋AF|1时,则Af1/F,且Xd0,XsXf③正反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|④自激:|1＋AF|0时,即AF=－1时则|Af|∞,且Xs=0时有输出Xo“振荡”··························与A无关！·反馈系数反馈增益回归比负反馈—反馈使净输入量减小，从而使输出量减小。正反馈—反馈使净输入量增加，从而使输出量增大。4.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度①负反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|②深度负反馈:|1＋AF|1时,则Af1/F,且Xd0,XsXf③正反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|④自激:|1＋AF|0时,即AF=－1时则|Af|∞,且Xs=0时有输出Xo“振荡”··························反馈系数反馈增益回归比4.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度FAXXsd11①负反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|②深度负反馈:|1＋AF|1时,则Af1/F,且Xd0,XsXf③正反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|④自激:|1＋AF|0时,即AF=－1时则|Af|∞,且Xs=0时有输出Xo“振荡”··························与A无关！·反馈系数反馈增益回归比VUo104.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度例:Au=105,R1=1k,R2=9kA+-Us·RLUo·＋－Ud·＋－510douUUAmVUd1.0令:则:10VFAXXsd11反馈系数反馈增益回归比VUo104.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度例:Au=105,R1=1k,R2=9kA+-Us·RLUo·＋－Ud·＋－510douUUAmVUd1.0令:则:10VR1R2F·Uo·＋－Uf·＋－FAXXsd11反馈系数反馈增益回归比回归比FAXXsd114.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度例:Au=105,R1=1k,R2=9kA+-Us·RLUo·＋－Ud·＋－10VR1R2F·Uo·＋－Uf·＋－121110RRRUUFofumVUd1.0令:则:10110101101155uuuusoufFFAAUUAVUo10510douUUA反馈系数反馈增益VUo104.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度FAXXsd11例:Au=105,R1=1k,R2=9kA+-Us·RLUo·＋－Ud·＋－510douUUAmVUd1.0令:则:10VR1R2F·Uo·＋－Uf·＋－121110RRRUUFofu10110101101155uuuusoufFFAAUUA)(10001.11ffdsfUVVUUUVU4.讨论XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度FAXXsd11①负反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|②深度负反馈:|1＋AF|1时,则Af1/F,且Xd0,XsXf③正反馈:|1＋AF|1时,则|Af||A|,且|Xd||Xs|④自激:|1＋AF|0时,即AF=－1时则|Af|∞,且Xs=0时有输出Xo“振荡”··························与A无关！·反馈系数反馈增益回归比5.分类(4种类型,组态)P353XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························增益传输系数环路增益闭环增益反馈深度①电压并联负反馈②电压串联负反馈③电流并联负反馈④电流串联负反馈反馈系数反馈增益回归比Is·＋－RLUo·Io·5.分类(4种类型,组态)XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························①电压并联负反馈dorIUA＋－Uo·ofgUIF＋－Ui·Id·If·出入入出a.负反馈.反馈极性判断:“瞬时极性法”b.电压型.c.并联型.d.电压负反馈:稳定输出电压！fsdIIIgrrsorfFAAIUA1Is·＋－RLUo·Io·5.分类(4种类型,组态)XsFARL＋XfXdXoAfXd=Xs－XfA=Xo/Xd[Au、Ai、Ar、Ag]F=Xf/Xo[Fu、Fi、Fg、Fr]T=A·F=Xf/Xd[Auf、Aif、Arf、Agf]D=1＋AFFAAXXAsof1·····························①