Transcript Document

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, 25m
 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 Cos t  I 2 m Cos 2t  
 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