Differential Amplifiers

射频共模抗扰度英文English:"Radiofrequency common mode rejection, often abbreviated as RF CMRR, refers to the ability of a system or device to reject unwanted signals or interference that appear simultaneously on both signal lines or conductors. It is a crucial parameter in electronic systems, especially in communication and instrumentation applications, where signal integrity is essential. RF CMRR is typically expressed in decibels (dB) and is calculated as the ratio of the desired signal to the unwanted common-mode signal. Higher RF CMRR values indicate better rejection of common-mode interference, leading to improved performance and reliability of the system. Achieving high RF CMRR involves various design techniques, including proper grounding, shielding, and balanced signal routing, as well as the use of differential amplifiers and filters to attenuate common-mode signals. Moreover, careful attention to component selection and layout plays a significant role in optimizing RF CMRR. Overall, RF CMRR is a fundamental aspect of ensuring the accurate transmission and reception of radiofrequency signals while minimizing interference and noise."中文翻译:"射频共模抗扰度，通常简称为RF CMRR，指的是系统或设备拒绝同时出现在信号线或导体上的不需要的信号或干扰的能力。

English | 日本語亚洲技术支持中心中文技术支持所有位置放大器专区讨论
4 回复最新回复: 2014-1-21 下午5:54 作者 ADIForum
ADIForum 2013-11-28 上午11:22
工程师百问百答——放大、电平搬移和驱动精密系
统
放大器是数据采集和传输系统的主要器件。

它们采集并放大来自传感器
和变送器的低电平信号，可从高噪声和高共模电压水平的环境下提取出
这些信号。

此外，放大器可以改变信号范围，并实现单端-差分转换（或
差分-单端转换），以便完全匹配ADC的输入范围。

ADI在线设计峰会2013，在10月底举办了“放大、电平搬移和驱动精密
系统”的主题研讨会，会后咱们的专家，放大器应用工程师David对大
家各种问题给出了详细的解答，我们选出了其中具有代表性的问题，整
理分享给大家。

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Re: 工程师百问百答——放大、电平搬移和驱动精密系统
此次会议的演讲PPT资料，请见附件
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16Date of Issue WORLDSKILLS QUALITY ASSURANCE STANDARD Document No.TD16 Approved Technical Description – Industrial Electronics Revision1WorldSkills (International Vocational Training Organisation), by a resolution of the Technical Committee and in accordance with the Constitution, the Standing Orders and the Competition Rules, has adopted the following minimum requirements for trade No. 16 for the WorldSkills Competition:The effective date will be that date on which this document is issued, subject to approval by the Chairman of the Technical Committee.1Name and description of trade1.1The name of the trade is:Industrial Electronics1.2The Industrial Electronics Technician works in industrial or commercialenvironments and works with or studies electronics. This includes:- development- construction- design- measuring- testing- repair1.3This technical description must be known to every candidate.1.4In the event of any query or conflict within the technical descriptions, the Englishcopy will take precedence1.5Words implying masculine gender only shall include the feminine gender2Scope of work at WorldSkills Competitions2.1The practical work will test the competitors ability to:- assemble, adjust, commission, measure and test electronic equipment- carry out and document measurements on analogue and digital circuits- locate, document and repair faults in a given circuit- design or refine a design of a circuit, and construct using prototypeconstruction techniques2.2To solve theoretical tasks using mathematical and graphical methods to aTechnician Level2.3To redraw a circuit drawing schematic with Computer Aided Design.Competitors must bring their own laptop and software of their choice.3Competition Format for Practical Work3.1AssemblingAssemble a project that has to be from a kit of parts to the IPC-A-610 issue Cinternational acceptability of electronic assemblies. (Web page/main/ipca/htm. Each project should be able to fit a Euro cardstandard using DIN 41612 F64 or F32connectors, that will fit a standard backplane connector. Power points will be as follows: -A1C1+5v DigitalA2C2Digital GroundA15+5v AnalogC15+12v AnalogA16C16Analog groundA17-5v AnalogC17-12v AnalogA31C31Digital GroundA32C32+5v Digital3.2Measuring and TestingTo work with conventional measuring and testing equipment for AC, DC, digitaland analog electronics. To test, set, adjust and measure electronic components,modules and equipment. To record and analyse measured results. Boards willbe pre-built before the competition.3.3Fault Finding and RepairTo test, locate and replace faulty electronic components on a printed circuitboard, surface mount board or mixed technology board.All surface mountcomponents to have no more than four pins and Fault finding method/procedurewith results will be required. All boards will be pre-built before the competition.Each board will have at least three faults. Pin configurations and power supplywill be as 3.0.Competitors may bring their own measurement instruments.3.4Prototype DesignTo carry out a simple electronic design using given components to meet a givenspecification. Printed circuit boards should be pre-built. Resistors E24 series,0.25 watt to be available from host country.No more than 15 wire wrapconnections and no more 15 point to point connections will be required on thismodule. Pin configurations and power supply will be as 3.0.Competitors may bring their own measurement instruments.3.5The competition is modular and will be marked at the end of every module.3.6Time allowed for each module is as follows:Theory 2 hoursDrawing 2 hoursPrototype 4 hoursFault Finding 4 hoursMeasurement 4 hoursAssembly Project 3 + 3 hours4Theoretical Knowledge4.1To solve theoretical problems, using mathematical and graphical methods basedon the following:4.1.1Fundamental electronic principles:1. Basics of AC and DC technology.2. Two ports LRC networks, resistive networks with up to three meshes.3. RC oscillators.4.1.2Components in Electronics:Properties, behaviour, characteristics and application (elementary circuits) ofmechanically, electrically and physically adjustable components i.e.:-Resistors-Capacitors-Coils-Transformers-Diodes: rectifying diodes, switch diodes, zener diodes, capacitive diodes, PIN diodes-Trigger components: diac, triac, thyristor and uni-junction transistors.4.1.3Multistage and special amplifier circuits:Basic amplifier circuits (AC, DC and power amplifiers)Differential amplifiers/operational amplifiers.1. Ideal operational amplifier: (infinite input resistance, zero outputresistance and infinite open loop grain) Basic circuits with operationalamplifier, analogue adder and subtractor, differentiator, comparator,impedance transducer.2. Real operational amplifier: Offset voltage and offset current,compensation, common mode gain and rejection, temperature drift,frequency response.4.1.4Generators and Pulse shapers:1. Generators for sine wave voltage: RC, quartz, LC oscillator; wien bridgegenerator, phase generator.2. Pulse shaper: Schmitt trigger, differentiator, integrator.4.1.5Digital Electronics1. Basic logic gates.2. Level switching function, function table, pulse, diagram, circuit symbols(table in appendix).3. Properties of basic gates AND, OR, NOT, NAND, NOR, EXCLUSIVE OREXCLUSIVE NOR.4. Substituting basic NAND or NOR gates for basic gates.5. Creating switching functions from given circuits and vice versa.6. Making function table from circuit diagrams and switching functions.7. Simplifying switching networks using Karnaugh diagram or mathematicaltechniques.8. Flip-flops; RS Flip-flop, D Flip-flop, JK Master slave Flip-flop (especiallycounter circuits, shift register and frequency divider).9. Memory circuits, selection, addressing, and memory decoding volume.5Materials5.1ComponentsThe workshop master must ensure that the materials provided are completed,packed in bags and checked also for the power supply project, and range of E24,0.25w resistors from 10 ohm to 10 megohms is supplied. The host country willalso supply the back plane as per drawing –Refer Document 4.3/PD16 – Project Design Criteria5.2Other materials1. Graph paper A3 size2. Solder 60/40 type3. Approx. 5m bare wire (0.5mm diameter) per competitor4. Approx. 5m each of insulated wire (or standard wire) in five differentcolours for each competitor5. Binding/insulation tape6. Lacing string /Tie raps/heat shrink sleeving7. Hot-air fan for heat-shrink tubing5.5ClothingWork clothes must comply with relevant safety standards. Safety standardsrequire a minimum of safety glasses and covered footwear.6Workshop Installations6.1The working area should provide enough space for the competitors, experts(jury), measurement and repair area, material cupboards and wardrobes.6.2The general layout of the workshop venue will be as below, with sufficient spacefor the booth and for the competitors working area as defined in 6.3 below.Key to the layout above is:Please note that this is an example of the layout, and is not definitive. The minimum area requirements will be available.6.2.1General RequirementsThe working area should provide enough space for the competitors, expert’s (jury), measurement and repair area, material cupboards and wardrobes.Lockable cupboards must be provided for the safe keeping of the materials and the examination papers under the responsibility of the chief expert.The organizers will provide four sets of the following for the experts:1. 4 x Hot-air fan for heat-shrink tubing2. 2 x Magnifiers for experts x3 or x53. 2 x Computers4. One Laser printer6.3The personal working area for each competitor should be about 3m x 3m, andshall also allow for the equipment and machines specified in Sec. 6.4 below.6.4Measuring Instruments and Tester/ToolsThe organisers will provide the following for each competitor:1. 1x universal DVM2. 1x Function generator 1-50 MHz, sine, square, triangle3. 1x stabilized power supply (3-30V adjustable)4. Various connection cables (if necessary, coax cable with BNC plugs)5. 1x Bench Lamp6. 1x Electrostatic workstation7. 1x Calculator, non-progammableThe organizers will also provide a spare set of the above for the experts.6.5Competitors must bring all their own tools, including wire-wrapping equipment.Measurement instruments are optional.Each competitor may send his tools ahead to the host country in a light, sturdy and lockable toolbox. A complete list of the contents must accompany the toolbox for Customs clearance i6.5.1Unauthorised tools are not permitted. In case of doubt, the competitor must applyto the Jury in advance. Their decision will take into consideration technological progress and the aim of the competition.7Test Project Marking7.1The experts will decide together on the test projects, the marking criteria and thedimensional tolerances on forms 5, and 6, and they will prepare the marking list.Any Country who has a project submitted and his/her candidate gains a largerscore and all the other competitors have a low score, the average of all the lowscores will be awarded to the country competitor who submitted the project.7.2Marks:Perfect = 10 pointsVery good = 9 pointsGood = 8 pointsRather good = 7pointsSufficient = 6 pointsMedium = 5 pointsWeak = 4 pointsInsufficient = 3 pointsVery bad = 2 pointsZero = 1 point7.3RatingSection Item Maximum PointsA Theory10B Drawing10C Prototype22D Fault Finding22E Measurement22F Assembly Project15GH7.4Conversion to the 400 - 600 scale will be done by computer.8Competition Procedure8.1The competition will be worked on over all four days of the competition. Moduleswill be completed on each day for all competitors so that progressive markingcan take place, and for results to be made available each day.8.2Competitors will have time made available to familiarise themselves with materialand processes. Where processes are particularly difficult, the host country willprovide a subject matter expert to demonstrate the process and the competitorswill be given the opportunity to practice.8.3The competitors will be given all competition documents including the markingcriteria one hour prior to the commencement of the competition so that they maystudy the requirements8.4Prior to the start of the competition, each competitor will receive a detailedtimetable reflecting the timing for completion of modules.8.5Project Design, Selection and Documentation will be carried out as specified inAppendix 1PCB information is provided in Appendix 68.6Ballot Selection of Competitors Work Areas, Competition Notes and Timetable8.6.1For a total random selection procedure, the country codes should be placed inone bin and workbench numbers in another. Alphabetically the countrycompetitors will select one piece of paper from each, and this is then the startbench for that country.8.7The rules and procedures, and timetable specified in Appendix 2, 3 and 4 mustbe complied with.9Judging procedural requirements9.1The experts that attend the competition will be divided into marking groups todeal with each section of the marking criteria.9.2Every completed module will be marked on the same day in which it wascompleted.10General safety requirements10.1All competitors must use safety glasses when using any hand, power or machinetools or equipment likely to cause or create chips or fragments that may injurethe eyes10.2All competitors must wear appropriate clothing.10.3All machinery, equipment and safety clothing must comply with the safety rulesof the organising country.10.4Competitors must keep their workspace clear of obstacles and the floor spaceclean of material and equipment - any items likely to cause the competitor to trip,slip or fall.10.5Failure by the competitor to comply with safety directions or instructions mayincur penalties for safety.10.8Judges will wear the appropriate personal safety equipment when inspecting,checking or otherwise working with a competitor’s project.10.9Safety Checklist must be adhered to and is provided in Appendix 511Additional Documentation11.1The following additional documentation relates to this trade.•Nil at present11.2The following additional documentation relating to this trade has yet to be definedat the next WorldSkills Competition to be held in St Gallen in 2003.•Document TM16 – Trade Management Procedures•Document WS16 – Workshop Setup•Document PD16 – Project Design CriteriaTrade 16 Electronics - Competition ManagementThe following Countries will provide the following at the 2003 competition.Country AssemblyProject MeasuringandTestingFaultFindingandRepairDesign/PrototypeTheory1 Digital1AnalogDrawingBrazil X XCanada X X X Finland X X X Germany X X XJapan X X X Korea X X X Macao XLit X X XMorocco X X Portugal X X X X Singapore X X X Switzerland X XTaiwan x X X Tunisia x x XUnitedKingdomx x x x Project Selection GuidelinesAll competition presentations will be made in English and before any project is presented for selection they must be checked that they conform to the current rules of the world skills, and the current Technical Description. If the rules are not followed the project will not be considered for selection. All documentation must adhere to the world skills rules otherwise it will not be selected. The experts will form into a project group with other countries under the same heading. They will then select either one or a number of projects for the competition, as for the timetable as 3:7. Experts will then present their selection to the rest of the experts. Following everyone’s approval the experts will then agree a marking scheme for the project/ projects. When the competition begins, these experts manage and mark that aspect of the competition under guidance from the Chief Expert.Project DocumentationProject documentation must be brought to the competition on 3.5” floppy disc format,/CD in Microsoft Word. Where experts have used a drawing software. Experts should bring along the version of the drawing program software that they used. Paper copies should also be presented and where possible in three official languages. Where possible circuit diagrams will be used for all modules and project wording should be as brief as possible. All projects must include the following:-1. Short project brief2. Parts list3. Circuit diagram4. Data sheet pack5. Projects will only be accepted with softwareFirst Time CountriesAny Countries attending the competition for the first time should contact the Chief Expert via world skills who will then forward previous competition documentation and agree a project in advance for consideration.Competition Rules for Competitors while working on their Projects1. You must not talk to your own country expert or visitor without the presence of one other expert2. If you have a question raise your hand.3. You must not leave your workstation without permission, except to obtain wire etc from centrebench.4. If you feel ill or require anything, raise your hand.5. You may not leave the stand without an escort except at scheduled times for lunch and visitsto other stands.6. You must not touch any project other than your own.7. You may not touch any other competitors equipment.8. If you finish and leave your stand early, you must leave the stand.9. No use of mobile phones is permitted.10. No talking to any people outside the stand area while you are working on a project.Competition Timetable - Trade 16 Industrial ElectronicsDay 1Step Activity Start time Finish time 1Introduction by Chief judge9.009.159.1509.452Demonstration of assembly rack andpower supplies3Start assembly10.0013.00 4Lunch13.0014.00 5Continue with assembly of project14.0017.00 Total competition time 6.00 Day 2Step Activity Start time Finish time 1Drawing Introduction9.009.30 2Drawing/C programming9.3011.30 3Tour around venue and lunch11.3012.00 4Theory Introduction12.4513.00 5Theory13.0015.00 6Break15.0015.15 7Demonstration of Fault Finding one project15.1515.30 8Fault finding one15.3017.30 Total competition time 6.00 Day 3Step Activity Start time Finish time 1Introduction to Design Project9.0009.30 2Design & prototype09.3012.30 3Lunch12.3014.00 4Demonstration of fault finding project14.0014.15number 25Fault finding14.1516.15 6Tour around venue16.1517.00 Total competition time 5.00 Day 4Step Activity Start time Finish time9.009.151Demonstration of Measurement andTesting project2Measurement project9.1512.15 3Lunch12.1513.30 4Demonstration of C programming project13.3014.005 C programming project14.0016.00 Total competition time 5.00 Overall competition time22.00FAIRNESSAs part of World Skills each competition is required to have a fairness of competition rules for the experts, which are listed below for your comments.Before the competition startsAll experts are to be trustedExperts to believe in each other and their valuesEffective management of timeCommunicate both accurate and completeKeep communication with team members user-friendlyBe a good listenerAs a team we value the contributions of its membersReach early agreement and our goals and have contingency plansCreate a vision of success for other competitions to followWe will not make preformed judgementsRecognise issues early and open dialogue then explore for common groundIf you have a visitor to the stand he/she must not speak to the competitorsBe united in our decisionsAlways show a united front when dealing with the competitorsWhen the competitors arriveYou must not talk to your own country competitor or visitor without the presence of one otherexpertYou must not leave the stand when your competitor is away from the stand unless in the presenceof another expertNo use of mobile phones is permitted.Health and Safety Check ListList each item A to C'A' = Satisfactory'B' = Unsatisfactory but rectified immediately'C' = Unsatisfactory - remedial action required1.Are all exits from the area free of obstruction?2.Are all gangways within the area free from obstruction?3.Are all fire fighting appliances at their designated, location, and access to them notobstructed?4.Do Experts / Competitors in the area know:a) Means of escape in emergency.b) The location of fire equipment and alarm points.c) What action to take if the evacuation alarm sounds.d) The action to take if a person is seriously ill / injured.5.Is the floor surface safe?6.Are items of furniture in a sound condition e.g. lockers, tables, chairs, benches etc.7.Are cables and extension leads on electrical equipment, at the plug?8.Are electrical wall sockets secure and in good condition.9.Are the following satisfactory:a) Lightingb) Ventilationc) Temperatured) Noise levele) Extraction10.Are "fittings" in a safe state, e.g. lights, service supplies etc.11.Are all items of handling equipment in a safe condition, e.g. trolleys etc. and up to date.(In the area)?15Are all filing cabinet drawers functioning correctly, and are drawers prevented from coming out by limit stops.16Are metal cabinets free from sharp edges.17Are the tops of units free from unsuitable objects.18Is there suitable storage provided (and used) for cabinet drawer locking bars, when not in use.19If applicable, are paper guillotines properly guarded.20Does the area demonstrate a satisfactory level of decent house-keeping? e.g. steps, ladders etc. (are they in good condition)?22Are heavy items stored on low level racks.24Are all personnel trained to use appropriate equipment in this area (see supervision)25Are there necessary restrictions being enforced e.g. entry of unauthorised persons.26Are flammable liquids and chemicals stored in appropriate environment correctly, e.g.gloves, goggles etc?28Are the edges of areas marked with a hazard stripe.29Are all equipment that require guarding, fitted with secure are serviceable guards?30Is eye protection being worn in appropriate areas.32Are there other items of safety equipment avqilable for use.33Are tools in good condition.34Are all raw materials or equipment safely positioned.35Is there a list of authorised persons who may use machines or equipment?36Are waste materials correctly disposed of?37If chemicals or substances are used, are they in suitable containers that are correctly marked?38Is safety information for chemicals or substances used available and known to the user?39Are the emergency stop buttons on equipment assessable and clearly marked?41Are competitors supervised.42Are free standing gas bottles secured.43Are all tools in use in good condition.44Are free standing gas bottles secure.45If applicable, have all system components been subjected to test, is a certificate available?46If applicable, is equipment within validation.47If applicable, is pipe work adequately secured.48Are there written procedures for :-a) Setting up for test.b) Test procedure.c) Making safe after test.50Are the necessary restrictions being enforced e.g. entry of unauthorised personnel. 51Do all personnel know the main isolation controls of the services being used?52Are cables and flexible hoses correctly routed to prevent accidents or damage?53If flammable liquids or chemicals are being use, are they :-a) Of minimal quantity.b) In approved containers.c) Correctly labelled.54Have reasonable safety precautions been taken against any foreseeable occurrence whilst carrying out the test.55If applicable, is the equipment correctly bonded / earthed.56If competitors or others are working in the area, are they under full supervision. Chief Expert (Signature)....................................................APPENDIX 6Specifications for PCB cardsMechanical spec.’sThe Europe format for PCB card is specified as follow (PCB only):All Dimensions are in millimeters. Tc = 160 mmThe Europe format for PCB card with a front plateIs specified as follow (with front plate and DIN41612 connector):All Dimensions are in millimeters. Tc = 160 mmFront Plate dimensions (if needed): 40,64 mm x 128,7 mm x 2,5 mmPCB connectorEach card must be designed with a DIN41612 male 64 pins a + c (C form)connector for PCB. The reference from HARTING is: 0903.164.6921.Mechanical dimensions of the connector。

为了测量电阻，我们使用单位“欧姆”。

To measure resistance,we use the unit "ohm".重要的是要应用这些定律。

It is important to apply these laws. 这种装置能用来测量电流电压电阻。

Such a device can be used to measurecurrent,voltage and resistance. 我们想要求这个电流中的电流。

We wish to find the current in the circuit.无线电波的用途之一是发送信息。

One of the uses of radio waves is to transmit intelligence.在这种情况下该物体被说成带电了。

In this case the object is said to be charged.我们感到理解这个概念很困难。

We find it very difficult to understand this concept.工科学生应该知道如何使用计算机。

Engineering studentsshould know how to use acomputer.物体做工的能力被称为能量。

The ability of a body to do workis called energy.重要的是我们要把理论应用于实践。

It is important for us toapply theory to practice.计算在这个电流中流动的电流密度是可能的。

It is possible tocalculate the current flowing inthis circuit.这些是常用的设备。

These arecommonly used devices.电压等取决于电路中的电阻以及所加的电压。

Voltage equalscurrent multiplied byresistance.显然电流与外加电压成正比。

运放使用指南1、反相放大器（The Inverting Amplifier ）基本反相放大器电路如图1所示。

其中，i V R R V ⨯-=12o ，213||R R R =，当12R R 的数值远小于op 开环增益时，这个数值就是反相放大器的增益，运算放大器的输入阻抗就是1R 的值，闭环增益单位增益带宽闭环增益带宽+=1在设计时要注意的是：3R 的阻值应该等于1R 和2R 的并联阻值，以减小输入偏置电流所带来的失调电压。

闭环增益输入失调电压输出失调电压⨯=。

运放输入端失调电压的主要来源是偏置电流（Input bias current ）和输入失调电压（Input offest voltage ）。

对于一个给定的op ，输入失调电压就已经确定了，但是由于输入失调电流所带来的失调电压与所采用的电路的结构有关系。

为了在不使用使调整电路的情况下，减小输入偏置电流所带来的失调电压，应该使得同相输入端和反相输入端对地直流电阻相等，使得由于偏置电流在输入电阻上压降所带来的失调电压相互抵消。

在低内阻信号源的放大器中，op 的输入失调电压将成为失调电压误差的主要来源。

在高输入阻抗的情况下，失调电压可以采用3R 的阻值来调整，利用输入偏置电流在其上的压降来对输入失调电压做补偿（即用这个得到的压降来抵消输入失调电压）。

在交流耦合时，失调电压并不显得很重要。

这时的主要问题是：失调电压减小了输入电压峰——峰值的线性动态范围。

工作范围在闭环状态下的op 和其反馈网络的增益——频率特性为了实现稳定，op 和反馈环路对任何频率的信号，在环路增益大于1时的环路相移的角度绝对不能超过o180。

在实践上，为了达到稳定条件，相移角度不应该接近o180。

对于一个给定的op 放大器电路，在进行电容补偿是需要在稳定性和带宽之间进行权衡。

加大补偿电容可以提高稳定性。

但是牺牲了放大器的增益带宽，反之亦然。

2、同相放大器（The Non-Inverting Amplifier ）图2是高输入阻抗的同相放大器电路，其闭环放大倍数121R R +=， V io图1 反相放大器其3dB 带宽闭环增益单位增益带宽=。