集成运放参数测试

romoting the construction of rule of law, but also the most basic development environment. Despite my good social order in General, but there are law-abiding consciousness, social order is not standard, regardless of faith, Twining visit visit and other outstanding problems. We want to actively promote the field of multi-level governance according to law, promote the continuous improvement of the social environment. To promote universal compliance. Actively foster the rule of law culture, carry out law publicity and education on honesty and trustworthiness, guide the masses and consciously abide by the law, failing to find method, problem-solving method, method of gradually changing the world, he is not looking for but someone unspoken rules, formed all law law, abide by the good atmosphere. To strengthen the comprehensive management of public security. Deepening peace xingan construction, strongly against violence crime, mafia and serious criminal offences, to protect the legitimate rights and interests of citizens, legal persons, carry out criminal policy of temper justice with mercy, the maximum stimulating social vitality, and earnestly safeguard social harmony and stability. To resolve social conflicts by law. To further smooth channels of reporting social conditions and public opinion, improving regulation, arbitration, as wellrelationship between Government and business. The two sessions, General Secretary of Pro, clear the word succinctly summarized the new relationship between Government and business, as pure politics, reshaping the political relationship specified in the direction. District leaders in handling political and business relations, engage in trading power for money, and finally stumbled, we a lesson, always keep in mind that Pro, clean practicing Pro, clear. Pro is to open a sincere engagement with private enterprise to help solve practical difficulties; Clear is to clarify the Division of power, exercised in accordance with, private entrepreneurs with innocent purity, not abusing power for personal gain, not to engage in trading power for money. Third, in order to maintain fairness and justice. Fairness and justice is the lifeline of the rule of law, is the best development environment. Currently, lax law enforcement and the judicial sector in our region also exist to varying degrees, law enforcement departments and individual window units power for personal gains and bribes, thick friends, relations, human cases, money cases in which seriously infringe on the legitimate rights and interests of enterprises and people. Especially some law enforcement and inspection for profit purposes, deliberately looking for corporate loopholes, found directly under the ticket does not give business improvement opportunities. We recruit a company doesnt easily, cultivating a business more difficult, never for personal gain, systematic harassment, card, last checked to check to get the enterprise collapsed. To guarantee the legitimate rights and interests. Always proceed from the overall situation of reform and development of services, fully consider the characteristics of production and management in non-public enterprises and social benefits, an accurate grasp of legal limits, protect the enthusiasm of entrepreneurs and practitioners in innovation and entrepreneurship, enhancing expectations and confidence. To promote strict enforcement. Strengthening law enforcement procedures, improve law enforcement performance evaluation, strengthening the supervision of law enforcement, exploration and practice of risk control mechanism of law enforcement to further standardize the social security, urban management, road traffic administrative law enforcement, effectively free, extensive law-enforcement and lax enforcement of law enforcement and other issues. To uphold justice. Justice is the last line of Defense to safeguard fairness and justice, to unequivocally support the courts and procuratorates independently exercise level . Judicial activities were rampant, must not be allowed to run, favors, money, must not be allowed to knowingly violate the miscarriage, violations of the legitimate rights and interests of the masses must not be allowed to abuse of power, to make forest mass can be felt in every judicial cases in equity and justice. Four to deepen grass-roots governance according to law实验 集成运算放大器参数测试一、实验目的：1通过对集成运算放大器A741参数的测试，了解集成运算放大器组件主要参数的定义和表示方法。2掌握运算放大器主要参数的测试方法。二、实验原理：集成运算放大器是一种使用广泛的线性集成电路器件，和其它电子器件一样，其特性是通过性能参数来表示的。集成电路生产厂家为描述其生产的集成电路器件的特性，通过大量的测试，为各种型号的集成电路制定了性能指标。符合指标的就是合格产品，否则就是不合格产品。要能够正确使用集成电路器件，就必须了解集成电路各项参数的含义及数值范围。集成电路的性能指标可以从产品说明书或器件手册查到，因此，我们必须学会看产品说明书和查阅器件手册。由于集成电路是半导体器件，而半导体器件的性能参数常常有较大的离散性，因此，我们还必须掌握各项参数的测试方法，这样才能保证在电路中使用的器件是合格产品，满足电路设计的需要。运算放大器的性能参数可以使用专用的测试仪器进行测试（“运算放大器性能参数测试仪”），也可以根据参数的定义，采用一些简易的方法进行测试。本次实验是学习使用常规仪表，对运算放大器的一些重要参数进行简易测试的方法。实验中采用的集成运算放大器型号为A741（同类产品有LM741，CF741，F007等），是一种第二代通用运算放大器，其内部结构可参看教材P85 图3-9集成运放F007的电路原理图，其引脚排列如图1所示。它是一种八脚双列直插式器件，其引脚定义如下：图 1 A741引脚、 调零端； 反相输入端； 同相输入端； 电源负极； 输出端； 电源正极； 空脚。以下为主要参数的测试方法：1输入失调电压：理想运算放大器，当输入信号为零时其输出也为零。但在真实的集成电路器件中，由于输入级的差动放大电路总会存在一些不对称的现象（由晶体管组成的差动输入级，不对称的主要原因是两个差放管的UBE不相等），使得输入为零时，输出不为零。这种输入为零而输出不为零的现象称为“失调”。为讨论方便，人们将由于器件内部的不对称所造成的失调现象，看成是由于外部存在一个误差电压而造成，这个外部的误差电压叫做“输入失调电压”，记作UIO或VOS。输入失调电压在数值上等于输入为零时的输出电压除以运算放大器的开环电压放大倍数：式中：UIO 输入失调电压 UOO 输入为零时的输出电压值AOD 运算放大器的开环电压放大倍数图2 UIO，IIO测试电路本次实验采用的失调电压测试电路如图2所示。闭合开关K1及K2，使电阻RB短接，测量此时的输出电压UO1即为输出失调电压，则输入失调电压 实际测出的UO1可能为正，也可能为负，高质量的运算放大器UIO一般在1mV以下。测试中应注意： 将运放调零端开路（即不接入调零电路）； 要求电阻R1和R2，R3和RF的阻值精确配对。2输入失调电流IIO当输入信号为的零时，运放两个输入端的输入偏置电流之差称为输入失调电流，记为IIO（有的资料中使用符号IOS）。式中：IB1，IB2分别是运算放大器两个输入端的输入偏置电流。输入失调电流的大小反映了运放内部差动输入级的两个晶体管的失配度，由于IB1，IB2本身的数值已很小（A或nA级），因此它们的差值通常不是直接测量的，测试电路如图2所示，测试分两步进行：1）闭合开关K1及K2，将两个RB短路。在低输入电阻下，测出输出电压UO1，如前所述，这是输入失调电压UIO所引起的输出电压。2）断开K1及K2,将输入电阻RB接入两个输入端的输入电路中，由于RB阻值较大，流经它们的输入电流的差异，将变成输入电压的差异，因此，也会影响输出电压的大小，因此，测出两个电阻RB接入时的输出电压UO2，从中扣除输入失调电压UIO的影响（即UO1），则输入失调电流IIO为：一般，IIO在100nA以下。测试中应注意：将运放调零端开路。 两端输入电阻RB应精确配对。3开环差模放大倍数Aod集成运放在没有外部反馈时的直流差模放大倍数称为开环差模电压放大倍数，用Aod 表示。它定义为开环输出电压UO与两个差分输入端之间所加差模输入信号Uid 之比：或 （dB）按定义Aod应是信号频率为零时的直流放大倍数，但为了测试方便，通常采用低频（几十赫兹以下）正弦交流信号进行测量。由于集成运放的开环电压放大倍数很高，而且在开环情况下UO的漂移量太大，难以直接进行测量，故一般采用闭环测量方法。Aod的测试方法很多，现采用交、直流同时闭环的测试方法，如图3所示。图3 Aod的测试电路被测运放一方面通过RF、R1、R2完成直流闭环，以抑制输出电压漂移；另一方面通过RF和RS实现交流闭环，外加信号US经R1、R2分压，使Uid足够小，以保证运放工作在线性区，同相输入端电阻R3应与反相输入端电阻R2相匹配，以减小输入偏置电流影响，电容C为隔直电容。被测运放的开环电压放大倍数为：Aod一般约为105（100dB）左右。测试中应注意：测试前电路应首先消振及调零。被测运放要工作在线性状态。输入信号频率应较低，一般用50100HZ，输出信号幅度应较小，而且无明显失真。4共模抑制比KCMR集成运放的差模电压放大倍数Aod与共模电压放大倍数Aoc之比称为共模抑制比，记为KCMR（或CMRR）。或图4 KCMR测试电路式中：Aod差模电压放大倍数；Aoc共模电压放大倍数。共模信号是指加在运算放大器两个输入端上幅值、相位都相等的输入信号，是一种无用的信号（常因电路结构、干扰和温漂造成）。理想运算放大器的输入级是完全对称的，其共模电压放大倍数为零，所以当只输入共模信号时，理想运放的输出信号为零；当输入信号中包含差模信号与共模信号两种成份时，理想运放输出信号中的共模成份为零。但在实际的集成运算放大器中，因为电路结构不可能完全对称，所以其共模电压放大倍数不可能为零，当输入信号中含有共模信号时，其输出信号中必然含有共模信号的成分。输出端共模信号愈小，说明电路对称性愈好，也就是说运放对共模干扰信号的抑制能力愈强。人们用共模抑制比KCMR来衡量集成运算放大器对共模信号的抑制能力。KCMR愈大，对共模信号的抑制能力越强，抗共模干扰的能力越强。KCMR的测试电路如图4所示。为了便于测试，采用闭环方式。集成运放工作在闭环状态下的差模电压放大倍数，根据使用的电阻值，用下面公式计算：图5 UICM测试电路使用图4的电路可测得共模输入信号Uic和共模输出信号Uoc，根据测得的Uic、Uoc值用下式计算出共模电压放大倍数：由Ad和Ac计算得共模抑制比：测试中应注意： 消振与调零； R1与R2、R3与RF之间阻值严格对称。输入信号Uic幅度必须小于集成运放的最大共模输入电压范围UICM5共模输入电压范围UICM集成运放所能承受的最大共模电压称为共模输入电压范围，超出这个范围，运放的KCMR会大大下降，输出波形产生失真，有些运放还会出现“自锁”现象以及永久性的损坏。(A)UICM的测试电路如图5所示。图6 UOPP测试电路被测运放接成电压跟随器形式，输出端接示波器，观察最大不失真输出波形，从而确定UICM值。6最大输出电压UOPP集成运放的最大输出电压又称输出电压动态范围，记为UOPP，该参数与电源电压、外接负载及信号源频率有关。测试电路如图6所示。改变US幅度，观察UO削波顶失真开始时刻，从而确定UO的不失真范围，这就是运放在某一定电源电压下可能输出的电压峰峰值UOPP。集成运算放大器在使用时应考虑的一些问题1）输入信号选用交、直流量均可，但在选取信号的频率和幅度时应考虑运放的频响特性和输出幅度的限制。图7 调零电路2）调零。为提高运算精度，在运算前，应首先对直流输出电位进行调零，即保证输入为零时，输出也为零。当运放有外接调零端子时（如A741的、脚），可按组件要求接入调零电位器RW，调零时，将运放输入端接地，用直流电压表测量输出电压UO，细心调节RW，使UO为零（即失调电压为零）。如运放没有调零端子，可按图7所示电路设置调零电路。一个运放如不能调零，大致有如下原因： 组件正常，接线有错误。 组件正常，但负反馈不够强（RF / R1太大），为此可将RF短路，观察是否能调零。 组件正常，但由于它所允许的共模输入电压太低，可能出现自锁现象，因而不能调零。为此可将电源断开后，再重新接通，如能恢复正常，则属于这种情况。 组件正常，但电路有自激现象，应进行消振。 组件内部损坏，应更换的集成块。3）消振。一个集成运放自激时，表现为即使输入信号为零，亦会有输出，使各种运算功能无法实现，严重时还会损坏器件。在实验中，可用示波器监视输出波形。为的消除运放自激，常采用如下措施 若运放有相位补偿端子，可利用外接RC补偿电路，产品手册中有补偿电路及元件参数提供。 电路布线，元、器件布局应尽量减少分布电容。 在正、负电源进线与地之间接上几十F 的电解电容和0.010.1 F的陶瓷电容相并联，以减小电源引入的影响。三、实验设备与元件1模拟电路实验箱 2信号发生器3双踪示波器4交流毫伏表5数字万用表6.集成运算放大器 F74117. 电阻器 512 ，51K2, 1K2 2K2, 10K2，100K28电解电容器 100F1四、实验步骤1 测量输入失调电压UIO按图2连接实验电路，闭合开关K1、K2，用直流电压表测量输出电压UO1，并计算UIO 。记入表1. 表1UIO（mV）IIO(nA)Aod(db)CMRR(db)实测值典型值实测值典型值实测值典型值实测值典型值注： 典型数据可查阅教材89页2. 测量输入失调电流IIO实验电路如图2,打开K1，K2，用直流电压表测量UO2,计算IIO。记入表1。3. 测量开环差模电压放大倍数Aod按图3连接实验电路，运放输入端加频率100HZ , 大小约为30mV50mV正弦信号作为Ui，用示波器监视输出波形。用交流毫伏表测量Uo和Ui,并计算Aod。 记入表1。4. 测量共模抑制比KCMR 按图4连接实验电路，运放输入端加 f = 100Hz , Uic = 12V正弦信号，监视输出波形。测量Uoc 和 Uic,计算Ad 、AC 及 KCMR ,记入表1。五、实验报告1. 将所有测得的数据与典型值进行比较。2. 对实验结果及实验中碰到的问题进行分析、讨论。六、预习要求1查阅集成运算放大器 A741 典型指标数据及管脚功能。2根据查阅的典型数据，计算可能的数据值（如Uo1,Uo2等），以供实验时参考。3. 测量输入失调参数时，为什么运放反相端及同相输入端的电阻要精选，以保证严格对称?4. 测量输入失调参数时，为什么要将调零端开路，而在进行其它测试时，则要求对输出电压进行调零?5. 测试信号的频率选取的原则是什么？ 保证的概念：保证人和债权人约定，当债务人不履行债务时，保证人按照约定履行债务或者承担责任的行为。保证人，有代为清偿能力的法人、其他组织或者公民，可以作为保证人。法律禁止作为保证人的情形romoting the construction of rule of law, but also the most basic development environment. Despite my good social order in General, but there are law-abiding consciousness, social order is not standard, regardless of faith, Twining visit visit and other outstanding problems. We want to actively promote the field of multi-level governance according to law, promote the continuous improvement of the social environment. To promote universal compliance. Actively foster the rule of law culture, carry out law publicity and education on honesty and trustworthiness, guide the masses and consciously abide by the law, failing to find method, problem-solving method, method of gradually changing the world, he is not looking for but someone unspoken rules, formed all law law, abide by the good atmosphere. To strengthen the comprehensive management of public security. Deepening peace xingan construction, strongly against violence crime, mafia and serious criminal offences, to protect the legitimate rights and interests of citizens, legal persons, carry out criminal policy of temper justice with mercy, the maximum stimulating social vitality, and earnestly safeguard social harmony and stability. To resolve social conflicts by law. To further smooth channels of reporting social conditions and public opinion, improving regulation, arbitration, as wellGrass-roots governance according to law is an important foundation for promoting the construction of rule of law, but also the most basic development environment. Despite my good social order in General, but there are law-abiding consciousness, social order is not standard, regardless of faith, Twining visit visit and other outstanding problems. We want to actively promote the field of multi-level governance according to law, promote the continuous improvement of the social environment. To promote universal compliance. Actively foster the rule of law culture, carry out law publicity and education on honesty and trustworthiness, guide the masses and consciously abide by the law, failing to find method, problem-solving method, method of gradually changing the world, he is not looking for but someone unspoken rules, formed all law law, abide by the good atmosphere. To strengthen the comprehensive management of public security. Deepening peace xingan construction, strongly against violence crime, mafia and serious criminal offences, to protect the legitimate rights and interests of citizens, legal persons, carry out criminal policy of temper justice with mercy, the maximum stimulating social vitality, and earnestly safeguard social harmony and stability. To resolve social conflicts by law. To further smooth channels of reporting social conditions and public opinion, improving regulation, arbitration, as well as dispute resolution mechanisms, implement fully the petitioners cases third-party hearings and supervising system of letters and calls, and to resolve the involved law lawsuit into the orbit of rule of law, vexatious, Twining visit visit, disturbing social order and other malicious extortion, resolutely crack down. Five,