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Analog Electronics Instructor: Prof Li Xia Office: Rm 558, office building Tel: 26557337 email: [email protected] website: http://cie.szu.edu.cn/fae Analog Electronics Goal — to provide students a good understanding of the basic principles of analog electronic circuits Textbook 李春茂改编, Allan R. Hambley著, Electronics, second edition, 电子工业出版社,2005年8月. References: 1. Electronics, D.I.Crecraft, Chapman&Hall 2. 江晓安,模拟电子线路,西安电子科技大学出版社 Assessment pattern: 40% coursework (experiments, presence, homework) 60% final exam Analog Electronics Electronic circuit design is fun. You can earn a good living from it and impress many people to whom electronics seems the magic. Outline 1 Introduction 2 Operational Amplifiers 3 Diodes and Diode Circuits 4 Bipolar Junction Transistors 5 Differential and Multistage IC Amplifiers 6 Frequency Response 7 Feedback 8 Output Stages and Power Suppliers 9 Active Filters Chapter 1 Introduction Electronic systems The design process Integrated circuits Basic amplifier concepts Cascaded amplifiers Differential amplifiers 1.1 Electronic systems Electronic systems are everywhere in our daily life. radio, television, refrigerator, MP3&MP4 GPS (global positioning system), air traffic-control system electronic instrumentation (signal generator, oscilliscope, multimeter) computerized monitors for patients Electronic systems are composed of subsystems or functional blocks. amplifiers, filters, signal sources, wave-shaping circuits, digital logic functions, digital memories, power suppliers and converters. 1.1 Electronic systems Amplifier — increase the power level of weak signals Filers — separate desired signals from the undesired and noise Signal source generators — generate waveforms Wave-shaping circuits — change one waveform into another Power supplies — provide necessary DC power to others Converters — change between analog and digital 1.1 Electronic systems Figure 1.1 Block diagram of a simple electronic system: an AM radio. 1.1 Electronic systems Many electronic systems falls into one or more of these categories: digital-signal processing systems, communication systems, medical electronics, instrumentation, control systems, computer systems. The primary concern of many electronic systems: to extract, store, transport, or process the information in a signal Some are concerned mainly with the power content of signals. A cardiac pacemaker uses information extracted form the electrical signals produced by the heart to determine when to apply a stimulus in the form of a minute pulse of electricity to ensure proper pumping action. 1.1 Electronic systems Analog versus digital signals Information-bearing signals can be either analog or digital. ADC DAC Figure 1.2 Analog signals take a continuum of amplitude values. Digital signals take a few discrete amplitudes. 1.1 Electronic systems Relative advantages of analog and digital systems Noise is any undesired disturbance added to the desired signal. One of the most significant advantages that digital systems have, compared with analog systems, is in the way that noise affects the signals. Figure 1.5 After noise is added, the original amplitudes of a digital signal can be determined. This is not true for an analog signal. 1.1 Electronic systems In general, analog systems requires fewer individual circuit components than do digital systems. Discrete circuits — circuit components are manufactured separately Integrated circuits — all at one time by a small number of steps Digital circuits tend to be easier to implement with IC technology. Digital systems are more adaptable to a variety of uses. Many of the input and output signals are analog. Furthermore, many functions – particularly those that deals with low signal amplitudes or very high frequencies – require an analog approach. The availability of complex digital circuits have actually increased the amount of analog electronics in existence because many modern systems contain both digital and analog portions, but would not be feasible as either totally digital or totally analog systems. 1.2 The design process Figure 1.6 Typical flowchart for design of electronic systems. System designer designs the block diagrams of the electronic system. 1.2 The design process Figure 1.7 Flowchart of the circuit-design process. Circuit designers select the proper devices and determine how to interconnect them to realize the blocks in the system. 1.2 The design process The need for documentation Accurate and complete documentation throughout the design process is very important. Contents include: circuit diagram, mechanical drawings, parts list, testing procedures, records of waveforms or measurements at various points in the circuit, an explanation of the operation of the circuit, wiring list … Information must be kept in written or machine-readable form, so that it is available to others working on a given system and not entrusted to memory. 1.3 Integrated circuits 1906, Lee DeForest, vacuum triode (amplifying and switching device) 1920s spread of radio broadcasting 1930s television 1940 the electronic computer 1947, William Shockley (AT&T), solid-state transistor Doping, free electrons, holes Bipolar junction transistor (BJT) Metal-oxide-semiconductor field-effect transistor (MOSFET) 1958, Jack Kilby (TI), Noyce and Moore (fairchild), integrated circuit Combines BJTs, MOSFETs, resistors, and capacitors, as well as their interconnections, into a functional circuit on a single chip. 1.3 Integrated circuits 1960s, 100 devices, 25m Today, >10 million devices, 0.25 m (A human hair is about 0.25 m in diameter.) We can anticipate even greater advances in the field of electronics. These advances will result from teamwork by physical electronics scientists, process designers, circuit designers, and system designers. 1920s spread of radio broadcasting Physical electronics scientists the physical principles of electronic materials and devices Process designers design the manufacturing processes for devices and ICs 1.4 Basic amplifier concepts same waveshape larger amplitude vo(t)=Av vo(t) Load resistor RL Voltage gain Av=Vo/Vi Often, one of the input terminals and output terminals are connected to a common ground. Figure 1.15 Electronic amplifier. 1.4 Basic amplifier concepts Figure 1.16 Input waveform and corresponding output waveforms. 1.4 Basic amplifier concepts iC I 0 I1m Cost I 2 m Cos 2t Open-circuit voltage gain Avo Input resistance Ri Output resistance Ro Think over: write an expression for vo and state what happens if the load is an open circuit? 1.4 Basic amplifier concepts Gain (增益) Voltage gain Open-circuit voltage gain Source voltage gain Current gain Power gain dB notation (P22) 1.4 Basic amplifier concepts Example : A source with an internal voltage of Vs=1mv rms and an internal resistance of Rs=1M is connected to the input terminals of an amplifier having an open-circuit voltage gain of Avo=104, an input resistance of Ri=2M , and an output resistance of Ro=2 . The load resistance is RL=8. Find the voltage gains Avs and Avo. Also find the current gain Ai and power gain G. Exercise P17 1.2, 1.3 Attention: What value of load resistance maximizes the power gain? Review: Maximum Power Transfer Theorem 1.5 Cascaded amplifiers The overall voltage gain of cascaded amplifier stages is the product of the voltage gains of the individual stages. Think over: If Avo1=100, Avo2=200, what is the overall open circuit voltage gain of cascaded amplifier? Avo=Avo1 Avo2 (refer to p17) 1.5 Cascaded amplifiers Applications calling for high or low input impedance Applications calling for high or low output impedance Application calling for a particular impedance Refer to examples shown on page 26-27 1.6 Differential Amplifier Characteristics of differential amplifiers Two input source Output proportional to the difference between the input voltages (For ideal amplifier) 1.6 Differential Amplifier Two types of input signals Differential input signal vid=vi1-vi2 Differential gain vo=Advid Common mode input signal vicm=(vi1+vi2)/2 Common-mode gain vo=Acmvicm The output voltage of a real differential amplifier vo=Advid+Acmvicm For well-designed differential amplifiers, Ad>>Acm CMRR (common-mode rejection ratio) CMRR=20lg (|Ad|/|Acm|) Try to understand common-mode input signal and differential input signal through reading the example on page 36. Summary Functional blocks of electronic systems System design & circuit design Advantages of digital systems over analog ones Why do both systems coexist? Discrete circuit & integrated circuit Equivalent circuit for an amplifier Cascade amplifier and Loading effect (IDEAL) Differential amplifier Exercise 1.1~1.5, 1.8, D1.9, 1.10~1.12, 1.13~1.14, 1.15~1.16, 1.18~1.19, 1.21, 1.37, 1.59, 1.60