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ached)andon-timecontrolproblems;severitygreaterrisk,accordingtotherequiredtroubleshooting,registrationform,andsignedbythoseresponsibleforthesecurityoftheunitforthefirstafterescalation.Thirdarticleopenminemanageroncoalmineproductionjobdistrictwithinofsecurityhiddentroubleshooting,andgovernanceandreportfullisresponsiblefor;securityDeputyManagertieManagerwork,theparagraphconstructionteamheadandthebusinessdepartmentheadMember,andrunmaintenancepersonnel,areshouldaccordingtotheirofdutiesrange,onproductionequipment,andfacilities,andsiteenvironment,aspectsofsecurityhiddenforcheckandreport,andbyhiddenrectificationprogrammeforhiddengovernance.Fourthopen-pitminesafetysectionisresponsibleforthesupervisionandinspectionintheproductionareatroubleshooting,managementandreportingofcomprehensivework.Articlescopeandfocusoftheinspectionpersonnelatvariouslevels:1,operatingpersonnelbeforetakingoverandshiftbeforethejurisdictionareatoconductacomprehensiveinspectionofequipment,runningthesquadlea第三部分 模拟电子技术基础实验

实验1 阻容耦合放大器的设计与调测

3.1.1实验目的

1．能根据一定的技术指标要求设计出单级放大电路。 2．研究单级低频小信号放大器静态工作点的意义。 3．掌握放大器主要性能指标的测试方法。 4．掌握用射随器提高放大器负载能力的方法。

3.1.2实验原理与设计方法

在晶体管放大器的三种组态中，由于共射极放大器既有电流放大，又有电压放大，所以在以信号放大为目的时，一般用共射放大器。分压式电流负反馈偏置是共射放器广为采用的偏置形式，如图3.1.1.所示。它的分析计算方法，调整技术和性能的测试方法等，都带有普遍意义，并适用多级放大器。

+VccRwRb1RRc+C2I1C1+TRLu0RsRb2Reui+Ce

电路中Rc为晶体管的直流负载，其交流负载由Rc与外接负载RL组成。由Rb1、Rb2及RC组成电流反馈式偏置电路，发射极交流旁路电容Ce是用来消除Re对信号增益的影响，隔直电容Cl、C2是将前一级输出的直流电压隔断，以免影响后一级的工作状态，同时将前一级输出的交流信号耦合到后一级。

1．静态工作点

放大器的静态工作点是指当放大器没有信号输入时，晶体管各极的直流电流和直流电压在特性曲线上所决定的点。

静态工作点选择是否合理，将直接影响放大特性的好坏，为使信号得到不失真的放大，放大器的工作点一般选在线性区的中点。但在小信号放大器中，由于输入信号小，运用范围也小，工作点可选低一些，以减少直流功耗。

通常，为了使工作点稳定，应先稳定ICQ，而ICQ≈IEQ，因此，只要稳定了IEQ也就稳定了ICQ，如能满足I1≥IBQ，VB≥VBE，则VB?是恒定的。

erondutyduringmajorequipmentoverhaul,beforeandaftertheshifttodesignatedstafftounderstandtheoperationofequipmentintheequipmentandcheckonfocus.2,equipmentrepairequipmenttoselectmaintenancecheckatleasttwiceaweektokeyequipmentanddefectivedevicestoincreasethefrequencyofinspection.Teamleaderdedicatedtothedeviceeverydayoperationofalldeviceswithinthescopeofmaintenancepersonnelunderstandthemaintenanceandinspectionofkeyequipment.Paragraph3,theownerandprofessionalandtechnicalpersonnelshouldbecarriedoutdailyafterworksitevisitinspection...Evening.Controlroom:focusedoncoalseamspontaneouscombustionundertroubleshooting,help,landslide,coalfire,earth-moving,roadcarwallsitesafetysupervision,andconscientiouslyimplementtheminerectificationmeasures.Productiontechnologysection:isresponsiblefortroubleshootingwhetherexistsSupercapacity,andSuper图 3.1.1单组阻容耦合放大器VCCRb2几乎与晶体管的参数无关，可近似值看成

Rb1?Rb2ached)andon-timecontrolproblems;severitygreaterrisk,accordingtotherequiredtroubleshooting,registrationform,andsignedbythoseresponsibleforthesecurityoftheunitforthefirstafterescalation.Thirdarticleopenminemanageroncoalmineproductionjobdistrictwithinofsecurityhiddentroubleshooting,andgovernanceandreportfullisresponsiblefor;securityDeputyManagertieManagerwork,theparagraphconstructionteamheadandthebusinessdepartmentheadMember,andrunmaintenancepersonnel,areshouldaccordingtotheirofdutiesrange,onproductionequipment,andfacilities,andsiteenvironment,aspectsofsecurityhiddenforcheckandreport,andbyhiddenrectificationprogrammeforhiddengovernance.Fourthopen-pitminesafetysectionisresponsibleforthesupervisionandinspectionintheproductionareatroubleshooting,managementandreportingofcomprehensivework.Articlescopeandfocusoftheinspectionpersonnelatvariouslevels:1,operatingpersonnelbeforetakingoverandshiftbeforethejurisdictionareatoconductacomprehensiveinspectionofequipment,runningthesquadlea而 IEQ?VEQRe?VBQ?IBERe?VBQRe

这样可以看成是稳定的。 在选择偏置电路元件参数时，既要考虑到满足工作点稳定的条件，同时又要兼顾电路其它方面（如放大倍数）的性能，因此，一般选取

I1?(5~10)IBQIBQ?ICQ

?VBQ?(5~10)VBE (3.1.1)

因此VBQ≥VBE ∴VBQ≈VEQ

ICQ=?IBQ

VCEQ≈VCQRC—VEQ （3.1.2）

由电路可得偏置元件的计算公式

Rb2?Rb1?Re?VBQI1?VBQ(5?10)IBQ

VCC?VBQI1IEQ?VBQ?VBEICQVEQ（3.1.3）

实际中Rb1通常用一固定电阻与电位器串联，以便调整工作点IBQ。

电源电压VCC的变动，负载RC的改变都会影响静态工作点，因此，静态工作点就取决于IBQ的选择，调节偏置电阻Rb1值，从而使工作点尽量选在交流负载线的中央。

2．动态范围（最大输出幅度）

放大器的最大不失真输出信号的峰值称为放大器的动态范围，则VOPP?2VOM

?22VO。

动态范围的大小，与VCC、RC及工作点均有关系。只要选择适当，就能保证得到所需的动态范围。

（1）选择电源电压的动态范围

如设计要求有一定的动态范围，应根据RL、VOPP、VE来选择放大器的工作状态。则

VCC?1.5(2Vom?VCES)?VE （3.1.4）

因VCES为晶体管的反向饱和压降，一般小于1V，计算时可取为1V。VE为晶体管的射极电压。一般锗管取（1～3）V，硅管取（3～5）V。

（2）选择直流负载RC

当VCC确定后，根据对动态范围的要求，可选定RC值。

RC?(VCC'VCES?2)RL (3.1.5)

Vom其中，VCC′=VCC－VE

3.1.5或适用于多级放大器，对于单级放大器的直流负载电阻RC，可按给定的RL、β、RS值算出。

erondutyduringmajorequipmentoverhaul,beforeandaftertheshifttodesignatedstafftounderstandtheoperationofequipmentintheequipmentandcheckonfocus.2,equipmentrepairequipmenttoselectmaintenancecheckatleasttwiceaweektokeyequipmentanddefectivedevicestoincreasethefrequencyofinspection.Teamleaderdedicatedtothedeviceeverydayoperationofalldeviceswithinthescopeofmaintenancepersonnelunderstandthemaintenanceandinspectionofkeyequipment.Paragraph3,theownerandprofessionalandtechnicalpersonnelshouldbecarriedoutdailyafterworksitevisitinspection...Evening.Controlroom:focusedoncoalseamspontaneouscombustionundertroubleshooting,help,landslide,coalfire,earth-moving,roadcarwallsitesafetysupervision,andconscientiouslyimplementtheminerectificationmeasures.Productiontechnologysection:isresponsiblefortroubleshootingwhetherexistsSupercapacity,andSuperached)andon-timecontrolproblems;severitygreaterrisk,accordingtotherequiredtroubleshooting,registrationform,andsignedbythoseresponsibleforthesecurityoftheunitforthefirstafterescalation.Thirdarticleopenminemanageroncoalmineproductionjobdistrictwithinofsecurityhiddentroubleshooting,andgovernanceandreportfullisresponsiblefor;securityDeputyManagertieManagerwork,theparagraphconstructionteamheadandthebusinessdepartmentheadMember,andrunmaintenancepersonnel,areshouldaccordingtotheirofdutiesrange,onproductionequipment,andfacilities,andsiteenvironment,aspectsofsecurityhiddenforcheckandreport,andbyhiddenrectificationprogrammeforhiddengovernance.Fourthopen-pitminesafetysectionisresponsibleforthesupervisionandinspectionintheproductionareatroubleshooting,managementandreportingofcomprehensivework.Articlescopeandfocusoftheinspectionpersonnelatvariouslevels:1,operatingpersonnelbeforetakingoverandshiftbeforethejurisdictionareatoconductacomprehensiveinspectionofequipment,runningthesquadleaAV?（3）确定静态工作点Q

??RL'

RS?rbcVCEQ?Vom?VCESICQ(VCC'?VCES)Vom ?RC计算出VCEQ及ICQ后，应作直流与交流负载线，如果选择的Q点不符合要求，可在VCC的选择上作出修改，若按3.1.5式计算出的RC也要作相应的修改。

3．频率特性

阻容耦合放大器，由于耦合电容C1、C2及旁路电容Ce的存在，以及分布电容，分布电感及晶体管结合电容存在等因素，将直接影响放大器的增益AV，使AV随信号频率而变化，其变化曲线称为频率响应曲线。如图3.1.2。

Av0.707AvBw0fL图3-1-2 频率特性曲线fHf

对于低频放大器的设计，高频特性的考虑只要在选择晶体管时，满足fβ≥fH就可以了。重点考虑低频特性满足技术的要求。因此，在计算耦合电容和旁路电容时，可按下列公式计算。（在Rb≥rbe的情况下）

C1?C2?1?L(RS?rbe)1?(3~10) (3.1.6) ?(3~10) (3.1.7)

(3.1.8)

?L(RC?RL)Ce?(1??)1?L(RS?rbe)4．放大倍数

放大倍数是反映放大电路对信号放大能力的一个参数，有电压放大倍数、电流放大倍数之分，电压放大倍数是指输入，输出电压的有效值（或峰值）之比：

AV?由图3.1.1的等效电路可得

Vo ViAV??RL'RS?rbe (3.1.9)

放大倍数为测量，实际上是交流电压的测量，对于低频弦电压，可用晶体管毫伏表直接测量ui及uo。而对非正弦电压可通过示波器比较法进行测量，测量仪器连接如图3.1.3所示。

erondutyduringmajorequipmentoverhaul,beforeandaftertheshifttodesignatedstafftounderstandtheoperationofequipmentintheequipmentandcheckonfocus.2,equipmentrepairequipmenttoselectmaintenancecheckatleasttwiceaweektokeyequipmentanddefectivedevicestoincreasethefrequencyofinspection.Teamleaderdedicatedtothedeviceeverydayoperationofalldeviceswithinthescopeofmaintenancepersonnelunderstandthemaintenanceandinspectionofkeyequipment.Paragraph3,theownerandprofessionalandtechnicalpersonnelshouldbecarriedoutdailyafterworksitevisitinspection...Evening.Controlroom:focusedoncoalseamspontaneouscombustionundertroubleshooting,help,landslide,coalfire,earth-moving,roadcarwallsitesafetysupervision,andconscientiouslyimplementtheminerectificationmeasures.Productiontechnologysection:isresponsiblefortroubleshootingwhetherexistsSupercapacity,andSuper