1、Circuits and Analog Electronics 电路与模拟电子技术,Prof. Li Chen, School of Information Science and Technology, Sun Yat-sen University 中山大学信息科学与技术学院 陈立副教授 Email: ,10 级计算机科学 22,References： W. H. Hayt, Jr., J. E. Kemmerly and S. M. Durbin, Engineering Circuit Analysis, McGraw-Hill, 2005, ISBN 978-7-121-01667-7
2、. R. L. Boylestad and L. Nashelsky, Electronic Devices and Circuit Theory, Pearson Education, 2007, ISBN 978-7-121-04396-3. 高玉良, 电路与模拟电子技术, 高教出版社, 2004, ISBN 7-04-014536-7.,Circuits and Analog Electronics,Handouts available at: References： W. H. Hayt, Jr., J. E. Kemmerly and S. M. Durbin, Engineerin
3、g Circuit Analysis, McGraw-Hill, 2005, ISBN 978-7-121-01667-7. R. L. Boylestad and L. Nashelsky, Electronic Devices and Circuit Theory, Pearson Education, 2007, ISBN 978-7-121-04396-3. 高玉良, 电路与模拟电子技术, 高教出版社, 2004, ISBN 7-04-014536-7.,Circuits and Analog Electronics,Teaching Schedule,Ch1 Basic Concep
4、ts and Laws of Electric Circuits,1.1 Basic Concepts and Electric Circuits 1.2 Basic Quantities 1.3 Circuit Elements 1.4 Kirchhoffs Current and Voltage Laws,References: Hayt: Ch1, 2, 5; Gao: Ch1;,Circuits and Analog Electronics,Signal processing and transmission,1.1 Basic Concepts and Electric Circui
5、ts,Speaker,transmitter,1.1 Basic Concepts and Electric Circuits,Electrical power conversion and transmission,1.1 Basic Concepts and Electric Circuits,Question: What is the current through the bulb?,Concept of Abstraction,Solution:,1.1 Basic Concepts and Electric Circuits,Lumped circuit abstraction!,
6、A resistor is a circuit element that transforms the electrical energy (e.g. electricity heat); Commonly used devices that are modeled as resistors include incandescent, heaters, wires and etc;,A circuit consists of sources, resistors, capacitors, inductors and conductors; Elements are lumped. Conduc
7、tors are perfect.,Resistance: R = V/I, 1 =1V/A, ohm; Conductance: G = 1/R = 1A/V, siemens (S); 1S = 1A/V, i(t) = G v(t);,Instantaneous current and voltage at time t;,1.1 Basic Concepts and Electric Circuits,Understanding the AM radio requires knowledge of several concepts Communications/signal proce
8、ssing (frequency domain analysis) Electromagnetics (antennas, high-frequency circuits) Power (batteries, power supplies) Solid state (miniaturization, low-power electronics),The AM Radio System,Example 1: The AM audio systemExample 2: The telephone system,1.1 Basic Concepts and Electric Circuits,1.1
9、 Basic Concepts and Electric Circuits,The AM Radio System,A signal is a quantity that may vary with time. * Voltage or current in a circuit * Sound (sinusoidal wave traveling through air) * Light or radio waves (electromagnetic energy traveling through free space),The analysis and design of AM radio
10、s (and communication systems in general) is usually conducted in the frequency domain using Fourier analysis, which allows us to represent signals as combinations of sinusoids (sines and cosines).,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Frequency is the rate at which a signal os
11、cillates. Duration of the signal T, frequency of the signal f = 1/T.,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Visible light is the electromagnetic energy with frequency between 380THz (Terahertz) and 860THz. Our visual system perceives the frequency of the electromagnetic energy
12、as color: is 460THz, is 570THz, and is 630THz. An AM radio signal has a frequency of between 500kHz and 1.8MHz. FM radio and TV uses different frequencies.,Mathematical analysis of signals in terms of frequency Most commonly encountered signals can be represented as a Fourier series or a Fourier tra
13、nsform. A Fourier series is a weighted sum of cosines and sines.,red,green,blue,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Fourier Series: A Fourier series decomposes a periodic function (or signal) into the sum of a set of sines and cosines. Given function f(t) with angular freque
14、ncy and period T, its Fourier series can be written as: f(t) = A0 + A1msin(t + 1) + A2msin(2t + 2) + =,1.1 Basic Concepts and Electric Circuits,Example: Given function during a period:,For the example :,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Example-Fourier Series,Signals can b
15、e represented in terms of their frequency components. The AM transmitter and receiver are analyzed in terms of their effects on the frequency components signals.,1st series + 3rd series,1st series (k = 1),3rd series (k = 3),1.1 Basic Concepts and Electric Circuits,The AM Radio System,The modulator c
16、onverts the frequency of the input signal from the audio range (0-5kHz) to the carrier frequency of the station (i.e. 605kHz-615kHz),Frequency domain representation of output,Modulator,Transmitter Block Diagram,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Input Signal,Output Signal,M
17、odulator: Time Domain,1.1 Basic Concepts and Electric Circuits,The AM Radio System,A typical AM station broadcasts several kW Up to 50kW-Class I or Class II stations Up to 5kW-Class III station Up to 1kW-Class IV station Typical modulator circuit can provide at most a few mW Power amplifier takes mo
18、dulator output and increases its magnitude,Power Amplifier,The antenna converts a current or a voltage signal to an electromagnetic signal which is radiated through the space.,Antenna,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Receiver Block Diagram,1.1 Basic Concepts and Electric
19、Circuits,The AM Radio System,The antenna captures electromagnetic energy and converts it to a small voltage or current. In the frequency domain, the antenna output is,Antenna,interferences,interferences,1.1 Basic Concepts and Electric Circuits,The AM Radio System,RF Amplifier amplifies small signals
20、 from the antenna to voltage levels appropriate for transistor circuits. RF Amplifier also performs as a Bandpass filter for the signal Bandpass filter attenuates the other components outside the frequency range that contains the desired station,RF (Radio Frequency) Amplifier,The AM Radio System,IF
21、(Intermediate Frequency) Mixer,The IF Mixer shifts its input in the frequency domain from the carrier frequency to an intermediate frequency of 455kHz,The IF amplifier bandpass filters the output of the IF mixer, eliminating all of the undesired signals.,IF Amplifier,1.1 Basic Concepts and Electric
22、Circuits,The AM Radio System,Computes the envelope of its input signal,Envelope Detector,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Audio Amplifier,Amplifies signal from envelope detector Provides power to drive the speaker,Hierarchical System Models,Modelling at different levels o
23、f abstraction Higher levels of the model describe overall function of the system Lower levels of the model describe necessary details to implement the system,In the AM receiver, the input is the antenna voltage and the output is the sound energy produced by the speaker. In EE, a system is an electri
24、cal and/or mechanical device, a process, or a mathematical model that relates one or more inputs to one or more outputs.,1.1 Basic Concepts and Electric Circuits,The AM Radio System,Top Level Model,Second Level Model,1.1 Basic Concepts and Electric Circuits,The AM Radio System,1.1 Basic Concepts and
25、 Electric Circuits,The Telephone System,The modern telephone system is developed from the following Electrical Engineering sub-disciplines: Signal processing: Speech compression, noise reduction, A/D and D/A conversion. E.g. channel coding + equalisation. Communications and networking: transmission
26、technologies, network architectures and protocols. Digital and computer: configurable switching hardware. Electromagnetics: microwave transmission hardware. Solid state: miniaturization, integration of complex systems onto a single chip. E.g. building a signal processing chips , called very-large-sc
27、ale integration(VLSI) Power Electronics: extremely reliable power supplies.,1.1 Basic Concepts and Electric Circuits,The Telephone System,An Early Phone System,1.1 Basic Concepts and Electric Circuits,The Telephone System,The major components include a carbon microphone and a speaker made from an el
28、ectromagnet and a paramagnetic diaphragm. Telephones were connected to the central office by twisted-pair wires. At the central office, calls were completed by a human operator at a switchboard-a physical connection between two telephones was made.,An Early Phone System,An Early Phone Circuit,Teleph
29、one Handset,Carbon Microphone,Earphone,Central Office,Battery,Telephone Handset,Carbon Microphone,Earphone,1.1 Basic Concepts and Electric Circuits,The Telephone System,The Modern Telephone System,A similar network structure . There are very significant differences: Data, video, and other signals ar
30、e transmitted along with speech. Calls are routed automatically under software control. Most transmission is digital.,1.1 Basic Concepts and Electric Circuits,The Telephone System,Analog Vs. Digital,An analog signal is a continuous signal represented over time domain:,A digital signal is a sequence
31、of 1s and 0s: 1101001010011100100110001001110,BPSK Input 1 , =0 Input 0 , =180,1.1 Basic Concepts and Electric Circuits,The Telephone System,Why Digital?,Analogue signal is prone to interference and degradation. Digital signal easily be retreated and repeat without any signal distortion - long dista
32、nce transmission. Can carry many types of information (phone, video, data, etc.) Digital hardware is less expensive. Digital data can be encrypted.,PCM-Pulse Code Modulation,A PCM encoder converts an analog signal into a digital signal with a particular format. A PCM decoder converts a digital signa
33、l into an analog signal. PCM is a form of quantization. PCM is a form of analog-to-digital (A/D) conversion.,1.1 Basic Concepts and Electric Circuits,The Telephone System,PCM-Pulse Code Modulation,PCM Encoder,A continuous signal is converted into a bit stream:,0 1 1,Involves three operations: Sampli
34、ng, Quantization and Encoding,The Telephone System,PCM-Pulse Code Modulation,Sampling: Value of the signal is obtained at equally spaced points in time:,Quantization: each sample is quantized to one of a finite number of values.,1.1 Basic Concepts and Electric Circuits,Ts sampling time . Fs=1/Ts sam
35、pling frequency .,The Telephone System,PCM-Pulse Code Modulation,Encoding: a pattern of bits is used to represent different output level of the quantizer; n bits can represent 2n quantizer output levels.,PCM decoder is one type of digital-to-analog (D/A) converter.,0000010100000000111111,1.1 Basic C
36、oncepts and Electric Circuits,We have 5 output levels , we need at least 3 bits to represent them.,Telephone Network,A house or business is called a subscriber. Typically, phone lines to houses or small businesses are analog twisted-pair wire connections. Subscribers analog lines are connected to a
37、Regional Terminal (RT) or to a Central Office (CO). At the RT or CO, the analog signal is converted to a digital signal.,The Telephone System,1.1 Basic Concepts and Electric Circuits,1.2 Basic Quantities,Units,Standard SI Prefixes 10-12 pico (p) 10-9 nano (n) 10-6 micro () 10-3 milli (m) 103 kilo (k
38、) 106 mega (M) 109 giga (G) 1012 tera (T),Electric charge (q) in Coulombs (C) Current (I) in Amperes (A) Voltage (V) in Volts (V) Energy (W) in Joules (J) Power (P) in Watts (W),Current,Time rate of change of charge,Constant current,Time varying current,1.2 Basic Quantities,A mount of electric charg
39、es flowing through the surface per unit time.,Current,Positive versus negative current,P1.1, In the wire electrons moving left to right to create a current of 1 mA. Determine I1 and I2.,Ans: I1 = -1 mA; I2 = +1 mA.,1.2 Basic Quantities,Current is always associated with arrows (directions),Voltage(Po
40、tential),Voltage,Units: 1 V = 1 J/C,1.2 Basic Quantities,Energy per unit charge. It is an electrical force drives an electric current.,Voltage (Potential),a,b,+Q from point b to point a get energy ，Point a is Positive? or negative ?,1.2 Basic Quantities,Example,Voltage (Potential),1.2 Basic Quantiti
41、es,Example,I,Voltage (Potential),Va=?,1.2 Basic Quantities,Example,I,I,I,1.2 Basic Quantities,Example,I,Power One joules of energy is expanded per second.,Rate of change of energy,P = W/t,Used to determine the electrical power is being absorbed or supplied if P is positive (+), power is absorbed if
42、P is negative (), power is supplied,p(t) = v(t) i(t),v(t) is defined as the voltage with positive reference at the same terminal that the current i(t) is entering.,1.2 Basic Quantities,Power,Example,1.2 Basic Quantities,Power,Power absorbed by a resistor:,1.2 Basic Quantities,Power,P1.5 Find the pow
43、er absorbed by each element in the circuit.,1.2 Basic Quantities,Supply energy : element 1、3、4 . Absorb energy : element 2、5,1.2 Basic Quantities,Loaded Circuit,1.2 Basic Quantities,1.3 Circuit Elements,Key Words: Resistors, Capacitors, Inductors, voltage source, current source,Passive elements (can
44、not generate energy) e.g., resistors, capacitors, inductors, etc. Active elements (capable of generating energy) batteries, generators, etc. Important active elements Independent voltage source Independent current source Dependent voltage source voltage dependent and current dependent Dependent curr
45、ent source voltage dependent and current dependent,1.3 Circuit Elements,Resistors,Dissipation Elements,v=iR,P=vi=Ri2=v2/R 0 ，,v-i relationship,1.3 Circuit Elements,Capacitors,Capacitance occurs when two conductors (plates) are separated by a dielectric (insulator). Charge on the two conductors creat
46、es an electric field that stores energy. The voltage difference between the two conductors is proportional to the charge: q = C v The proportionality constant C is called capacitance. Units of Farads (F) - C/V 1F= one coulomb of charge of each conductor causes a voltage of one volt across the device
47、.,1F=106F, 1F=106PF,1.3 Circuit Elements,Capacitors,store energy in an electric field,v-i relationship,1.3 Circuit Elements,vC(t+) = vC(t-),Capacitors,P1.7,1.3 Circuit Elements,For (1) :,Capacitors,P1.7,1.3 Circuit Elements,Inductors,store energy in a magnetic field that is created by electric passi
48、ng through it.,v-i relationship,Inductors connected in series: Leq= L1 + L2 + L3 + Inductors connected in parallel: 1/Leq=1/L1 + 1/L2 + 1/L3 + ,1.3 Circuit Elements,iL(t+) = iL(t-),Independent voltage source,practical,1.3 Circuit Elements,Independent current source,I,Ideal,practical,1.3 Circuit Elem
49、ents,Voltage source connected in series:,Voltage source connected in parallel:,1.3 Circuit Elements,Voltage controlled (dependent) voltage source (VCVS),Current controlled (dependent) voltage source (CCVS),Q: What are the units for and r?,1.3 Circuit Elements,Voltage controlled (dependent) current source (VCCS),Current controlled (dependent) current source (CCCS),Q: What are the units for and g?,1.3 Circuit Elements,Independent source,dependent source,Can provide power to the circuit; Excitation to circ
