网络电视业务实现方案研究

1、Chapter 10 Analog Integrated Circuits and its applicationIntroductionThe 741 Op-Amp CircuitThe ideal Op AmpThe inverting configuration The noninverting configurationIntegrator and differentiatorOther operation applicationIntroduction信号的提取：传感器、接收器或信号发生器，通常信号比较微弱，且易受 干扰，甚至与噪声的幅度相当。信号预处理：信号的分离与放大（隔离、滤波

2、与阻抗变换）信号的加工：信号的运算、转换和比较等。一般再经功放才能驱动负载， 或者经A/D转换到PC机信号的执行：一般为CPU（MCU，DSP，PC）Part 1. The 741 Op-Amp Circuit and analysis. Part 2. Analog integrated circuits application _ the application of operational amplifier _ the application of comparer circuits ContentPart I:Analog ICs include operational amplif

3、iers, analog multipliers, A/D converters, D/A converters, PLL, etc.A complete op amp is realized by combining analog circuit building blocks.The bipolar op-amp has the general purpose variety and is designed to fit a wide range of specifications.The terminal characteristics is nearly ideal.The 741 O

4、p-Amp CircuitStructure“化整为零”：划分偏置电路、输入级、中间级和输出级“分析功能”：分别分析各部分的结构形式及特点“统观整体” ：研究各部分电路之间的联系“定量估算”：必要时做定量分析General Description24 transistors, few resistors and only one capacitorTwo power suppliesShort-circuit protection The Input StageThe input stage consists of transistors Q1 through Q7.Q1-Q4 is the

5、differential version of CC and CB configuration.High input resistance.Current source (Q5-Q7) is the active load of input stage. It not only provides a high-resistance load but also converts the signal from differential to single-ended form with no loss in gain or common-mode rejection. The Intermedi

6、ate StageThe intermediate stage is composed of Q16, Q17 and Q13B.Common-collector configuration for Q16 gives this stage a high input resistance as well as reduces the load effect on the input stage.Common-emitter configuration for Q17 provides high voltage gain because of the active load Q13B.Capac

7、itor Cc introduces the miller compensation to insure that the op amp has a very high unit-gain frequency.The Output StageThe output stage is the efficient circuit called class AB output stage.Voltage source composed of Q18 and Q19 supplies the DC voltage for Q14 and Q20 in order to reduce the cross-

8、over distortion.Q23 is the CC configuration to reduce the load effect on intermediate stage.Short-circuit protection circuitryForward protection is implemented by R6 and Q15.Reverse protection is implemented by R7, Q21, current source(Q24, Q22) and intermediate stage. The Output Stage(a) The emitter

9、 follower is a class A output stage. (b) Class B output stage.The Output StageWave of a class B output stage fed with an input sinusoid.Positive and negative cycles are unable to connect perfectly due to the turn-on voltage of the transistors.This wave form has the nonlinear distortion called crosso

10、ver distortion. To reduce the crossover distortion can be implemented by supplying the constant DC voltage at the base terminals. The Output StageQN and QP provides the voltage drop which equals to the summer of turn-on voltages of QN and QP.This circuit is call Class AB output stage.The Biasing Cir

11、cuitsReference current is generated by Q12, Q11 and R5.Wilder current provides biasing current in the order of A.Double-collector transistor is similar to the two-output current mirror. Q13B provides biasing current for intermediate stage, Q13A for output stage.Q5, Q6 and Q7 is composed of the curre

12、nt source to be an active load for input stage.The Ideal Op Amplifiersymbol for the op ampThe Ideal Op AmplifierThe op amp shown connected to dc power supplies.Characteristics of the Ideal Op AmplifierDifferential input resistance is infinite.Differential voltage gain is infinite.CMRR is infinite.Ba

13、ndwidth is infinite.Output resistance is zero.Offset voltage and current is zero.No difference voltage between inverting and noninverting terminals.No input currents.iN = iP = 0uN = uP1. Differential input voltage is zero2. Input current is zerouo = Aod （ uN - uP ） Virtual short circuitVirtual disco

14、nnect circuitAod+-uNuPuoiNiPfeedbackWorking at linear region circuit with negative feedbackIdeal Op amplifier works at linear regionIdeal Op amplifier works at nonlinear regionuo Aod （ u+ - u- ） uo = + UOPP when u+ u- uo = - UOPP when u+ u- 1. Vo have only two value2. i+ = i- =0 Virtual disconnect-c

15、ircuitVirtual short circuit doesnt exsistEquivalent Circuit of the Ideal Op AmpThe Inverting Configuration Virtual short circuit.Virtual ground: that is, having zero voltage but not physically connected to groundVirtual disconnect-circuitThe Inverting Configuration The inverting closed-loop configur

16、ation.The Inverting Configuration Effect of finite open-loop gainThe Inverting Configuration Shunt-shunt negative feedbackClosed-loop gain depends entirely on passive components and is independent of the op amplifier.Engineer can make the closed-loop gain as accurate as he wants as long as the passi

17、ve components are accurate.Exercises: example 2.2Example2.2Homework:May 27th, 2009 2.8; 2.22The Non-inverting Configuration The noninverting configuration.Series-shunt negative feedback.The Noninverting Configuration Effect of finite open-loop gainThe Voltage followerThe unity-gain buffer or followe

18、r amplifier. Its equivalent circuit model.The Weighted SummerThe Weighted SummerExample 2.6: A Single Op-Amp Difference AmplifierLinear amplifier.Theorem of linear Superposition.A Single Op-Amp Difference AmplifierApplication of superpositionInverting configurationA Single Op-Amp Difference AmplifierApplication of superposition.Noninverting configuration.Integrators The inverting configuration with general impedances in the feedback and the feed-in paths.The Inverting Integrators The Miller or