Electronics Principles and Digital Design

Welcome to ELEC S222, Electronics Principles and Digital Design.

This course was adapted from the course T202 Analogue and Digital Electronics by the Open University in the U.K. Some aspects of the course presentation, however, are very different here in Hong Kong from the way they are in Britain. The main differences relate to the practical work associated with the course. In Britain, students are sent a 'Home Kit' consisting of electronic components, circuit modules and a 'Generatorscope' (a combined oscilloscope, signal generator and power supplies). With this kit, they are expected to carry out a large number of experiments in their own homes. We do not issue a home kit at HKMU, but instead, you are expected to attend several 'short laboratory' sessions where you will carry out the same experiments. Don't be confused by references in the course texts to 'home kits', 'home experiments' or 'the Generatorscope' — they are not relevant to you. You may also find references to 'Summer School'. This is a whole week of practical work, tutorials and lectures that OUUK students must attend. Here in Hong Kong, the same experiments are carried out at 'long laboratory' sessions held on Sundays later in the course.

This Course Guide has been designed to provide you with some essential information about the course and to assist you in planning the best use of your available study time. Sections 2 to 6 present an overview of the course and therefore help you see the course as a whole. You should therefore read these sections before you start work on Block 1.

You will also have received the Presentation Schedule in this mailing, which shows how long you should spend studying each block of the course. This schedule can help you to do the overall planning of your 34 weeks of study. To assist your detailed planning, Section 6 of this Guide contains detailed study guides to each of the blocks in the course, showing how you are expected to allocate your time to each of the individual components of a block. You will need to read the relevant Block Guide each time you start your study of a new block. These block guides will assist you in planning the detailed allocation of your study time week-by-week as you progress through the course. Section 6 also contains some 'study notes' that explain ideas or terms used in the texts with which U.K. students are assumed to find familiar, but which you may find confusing. 

If during your study of the course, you have difficulty understanding the course materials, you should contact your tutor, whose name, address and telephone number will be supplied to you by the HKMU Registry.

If you have not received course materials that you believe have been dispatched to you, or if the materials you receive are incomplete, you should contact Office for Advancement of Learning and Teaching (ALTO) at 2768 6446.

If you have any problems other than subject matters in the course materials or have any suggestions for improvements, please write to:

It is important in electronics to be able to do more than 'get the right answer' to a specific set of questions. As in all fields of study in which design is a major activity, the main task is to be able to solve new problems as well as to know the answers to previously solved problems. The kinds of tasks that arise in electronics include:

1. designing a circuit to meet a new performance specification,
2. explaining to someone else the reason why you have designed a circuit the way you have,
3. diagnosing the cause of an unfamiliar fault or a new sort of circuit behaviour so that you can correct it,
4. being able to argue the good and bad points of different circuits and ask important questions about them, and so on.

The common feature of all these activities is having the ability to cope sensibly with new and unexpected problems. So it is this 'capability', as it is called, that this course tries to help you acquire.

There are subsidiary aims that are much easier to teach and to learn which undoubtedly form part of the capability that the course is trying to help you develop. There are some tried and tested circuits that you ought to know about and whose performance you should be able to describe precisely. They often form the starting point for any one of the problem-solving tasks listed above. Equally, there are several techniques available, like using mathematics or drawing circuit diagrams, which help you analyse a problem in preparation for devising a solution to it. Knowing about these circuits and being able to use these techniques are the beginnings of electronic capability, and they are usually referred to as knowledge and skills. But understanding the circuits and how they are used, and grasping the concepts on which they depend are the key parts of capability. Capability is being able to use such knowledge and skills to solve new problems. It is the ability to go beyond the information given.

The course sets self-assessed questions (SAQs) and assignments to test your knowledge and skills, but to gain the understanding that you need requires you to tackle new problems, or at least problems that are new to you; to try to design things, to try to explain things in your own words, to try to diagnose faults, to ask sensible questions and so on. There may be no 'right' answers to these questions, they are developed to reveal to yourself, as well as to your tutor, your degree of understanding. Giving you model answers merely tempts you to learn the answers by heart instead of thinking about the problem. So the 'answers' that are provided may refer only to the sort of things you should have thought about. In trying to answer such assignments, the important thing is not whether you can solve the problem quickly, but whether you can show that you have understood the problem and can see how to tackle it successfully.

To make it clear that you are being asked to learn both knowledge and skills, as well as to acquire understanding, the course includes two kinds of objectives. The specific objectives are those you are used to. They lead to questions about what you know and about the calculations that you should be able to do. The general objectives lead to questions whose aim is to bring out what you understand and to reveal whether you have grasped the important concepts on which understanding depends.

The course contains several different components, closely integrated to produce a coherent teaching package. These components are as follows.

3.1 The main texts. These texts form the main teaching medium of the course, and you will spend most of your time reading these texts and answering the self-assessment questions (SAQs) that they contain. You must tackle the SAQs as you read through a block text, as they are the main means you have of testing whether you have understood the contents. These texts are arranged in blocks, with most blocks having several parts. The blocks vary in length, and the individual parts within a block are also usually of different lengths.

3.2 The glossary. The course glossary lists each of the new terms and concepts introduced in the course, with a very brief description of each and an indication of where, in the main texts, the term is introduced and described. Whenever a term is used, and you can't remember the meaning of it, you should first look in the glossary. The short description there mayserve to refresh your memory. If that description doesn't help, you should refer back to the main text where the term has been described in detail.

3.3 Home computing. Throughout the course, some home computing exercises require you to use Computer-Aided Design (CAD) software known as OrCAD to analyse circuit behaviour. These computing exercises are an essential component of the course, and the CAD software is provided as part of the course materials. You are required to have access to an IBM PC or compatible running Windows 7 (or later) and English Windows is preferred. You will find the software NODALOU and LOGANOU used in the main text. You can simply ignore them because OrCAD has replaced these old software packages.

3.4 Short laboratories. Several 'short laboratory' sessions spread throughout the course will be held in HKMU's laboratory on the Homantin campus. At these sessions, you will carry out experiments designed to reinforce the teaching of skills and knowledge and to assist in developing understanding. While attendance at these sessions is optional, much of the teaching in the texts assumes you have performed the experiments, so if you do not attend the texts will be harder to understand and learn from. Also, some of the assignments may contain questions that you might not be able to answer fully unless you have attended the short laboratory sessions. The detailed information of the short lab. will be provided in Stop Presses.

3.5 Long laboratories. There are two 'long laboratory' sessions to be held on Sundays in the HKMU laboratory near the end of the course. Each of these long labs lasts for a whole day, and provides an opportunity for you to engage in realistic design exercises, as well as to perform extended experiments to reinforce the teaching of essential concepts. Attendance at these sessions is compulsory. If you do not attend, you cannot pass the course.  The detailed information of the long lab. will be provided in Stop Presses.

3.6 Tutorials.  There will be regular face-to-face tutorial sessions with your tutor, supporting the teaching in the main texts. Exact information about the date, time and place of each tutorial will be provided in Stop Presses. Attendance at tutorials is optional.

3.7 Surgeries. Regular surgery sessions are scheduled throughout the course, a tutor will be available to answer specific problems that you may have with the course work. These 'surgery' sessions are intended to provide you with specific assistance with specific problems; the tutor will not run a tutorial, and will not have facilities for talking to more than a few students at a time. The surgeries provide the opportunity for you to resolve difficulties without having to wait for your next scheduled tutorial. Details of these surgery sessions will be sent to you in Stop Presses.

3.8 OLE. This course will use the Online Learning Environment (OLE). You are recommended to visit the OLE regularly.

The ELEC S222 Study Blocks will use the following blocks from T202.

Since ELEC S222 only uses part of the T202 course material, you can ignore the references to the unused blocks in T202.

Block 1 Introduction to signals and circuits (parts 1-5)

Part 1: Basic electrical principles
This text, as its name suggests, introduces some of the basic concepts with which all students need to be familiar before starting on the course subject matter proper in Part 2 of the block. Topics covered are: current, e.m.f., potential difference, electrical energy, electrical power, resistance and conductance, resistors in series and in parallel, and the measurement of current, voltage and resistance. A short lab introduces the use of a multimeter for the measurement of current, voltage and resistance, and contains some simple experiments to reinforce the concepts introduced in the text. One of the experiments provides data for the introduction of new concepts in Part 2 of the block.

Part 2: Methods of circuit analysis
This develops some of the fundamental tools of circuit analysis in the context of d.c. resistive circuits. These concepts include: Kirchhoff's current and voltage laws, nodal analysis, ideal voltage and current sources, Thévenin and Norton equivalent circuits, and the Superposition principle. There is no short lab associated with this part of the block, but there is a substantial home computing component.

Part 3: Signals and waveforms
This describes the nature and properties of the current and voltage waveforms that are handled by electronic circuits, with particular reference to sinusoidal waveforms, analogue signals and digital signals. It introduces ideas of: frequency spectra and bandwidth; signals, messages and carriers; noise and distortion; and how signals and waveforms are quantified. A short lab introduces the use of an oscilloscope and reinforces some of the concepts introduced in the text.

Part 4: Basic circuit components
This describes the nature and properties of some basic a.c. circuit components — namely, inductors, capacitors, transformers and rectifiers, and their response to both sinusoidal waveforms and sudden step changes of voltage or current. The role of the transistor as a power amplifier is also described. The concepts of linearity and the small-signal equivalent circuit are introduced.

Part 5: Amplifiers and amplification
This part of the block explains what is meant by amplification, and shows how feedback can be used with operational amplifiers to obtain different kinds of amplifier performance.

Block 3 Digital principles

Part 1: Combinational circuits
This is concerned with the basic principles of combinational logic circuits, introducing the binary number system, binary signals, gates, de Morgan's theorem, half-adder and full-adder, codes and code conversion.

Part 2: Logic design and implementation
This deals with the design of logic circuits. It describes the process of conversion from a truth table via a Karnaugh map to the circuit (consisting of a combination of logic gates) that implements the required logic function. Devices introduced to implement logic circuits include SSI (small-scale integration) devices such as AND, OR, NAND and NOR gates, MSI (medium-scale integration) devices such as decoders and AND-OR-INVERT gates, and programmable devices such as PALs (programmable array logic devices) and PROMs (programmable, read-only memories). The text ends with a description of the TTL (transistor-transistor logic) family of gate devices.

Part 3: Sequential circuits
This part of the block is concerned with the design of sequential logic circuits. It describes a design method using the concepts of a general sequential machine, state-transition diagram, state table and state assignment table. Specific sequential logic circuits are implemented using gates and memory elements such as D-type flip-flops. Counters are treated as a special set of examples of sequential logic circuits, and the design of synchronous counters using JK flip-flops is described. The text ends with descriptions of the 555 timer, integrated circuit counters and PLSs (programmable logic sequencers).

Part 4: Analogue-digital conversion
This final part of the block considers the conversion of analogue signals to digital form. It first describes the digital-to-analogue (D-A) converter, and then describes three different methods of analogue-to-digital (A-D) conversion — the flash converter, the counter-ramp converter and the successive approximation converter. It ends with descriptions of sample-and-hold devices and multiplexers. There is a short lab associated with this part of the block that requires you to investigate the characteristics of D-A and A-D converters.

The block ends with a substantial home computing component using OrCAD, the circuit analysis software.

Block 4 Transistors and basic circuits (parts 1 & 3)

Part 1: p-n junctions and transistors (Part 1 of T202 block 4)
This first part of the block looks at some of the physics underlying semiconductor devices, and explains the properties of diodes and transistors in terms of the properties of silicon and the structure of the devices. It also explains one application of the d.c. characteristics of the devices, and the design of d.c. current sources using transistors.

Part 2: Analogue transistor circuits (Section 1–2 Part 2 of T202 block 4, Page 48–59)
These two sections look at the way a transistor can be represented by an equivalent circuit, and how numerical values for the equivalent circuit parameters are obtained from datasheets and graphs of transistor characteristics.

Part 3: Digital transistor circuits (Part 3 of T202 block 4)
The remaining part of the block deals with digital transistor circuits. It starts by describing the switching properties of transistors and proceeds to describe the design of various widely-used families of transistor switching circuits — namely, TTL (transistor-transistor logic), ECL (emitter-coupled logic), NMOS (n-channel metal-oxide silicon) and CMOS (complementary metal-oxide silicon). The properties of a selection of these circuits are explained in terms of the properties of the transistors of which they are made.

Block 6 Digital systems

Part 1: Memory systems
This describes some of the circuit components used to store digital data, and how these components can be interconnected to form large memories. It deals with registers, RAM (random access memory), DRAM (dynamic RAM), SRAM (static RAM), and a range of different ROM (read-only memory) types.

Part 2: Microprocessors and microcontrollers
This describes the basic characteristics of a microprocessor and a microcontroller, and shows how such devices can be used as versatile components in digital and analogue circuit design. It introduces concepts such as: sequential operation, stored program, processor architecture, RISC (reduced instruction set computers) and CISC (complex instruction set computers). It goes on to describe in detail a commercially available device, the Motorola MC68HC05B6 microcontroller, and an application of the device in the control of a domestic washing machine. The block ends with a look at an example of the digital processing of analogue signals.

The assessment of this course consists of a continuous assessment component and a final examination. Your progress throughout the course (the continuous assessment component) will be assessed through one Assignment (Multiple Choices) and Assignments. All of them are required for assessment. At the end of the course, you will be required to sit a three-hour examination.

Your overall course mark will be calculated from the results of your assignments and your examination result as follows:

The Assignments 01, 02 & 04 and the Assignment (Multiple Choices) are used to assess your progress with the main texts, the home computing and the short labs. Assignment 03 will assess your performance in the long laboratories.

The final examination is a written paper of three hours, and you will attempt the questions without the help of any notes or printed materials relating to the course. A simple scientific calculator is allowed. You will be sent a Specimen Examination Paper, which resembles the actual paper in both style and format, so that you can get some idea of what to expect.

The course grade is mainly determined by the overall course score (CS) yet students are normally required to obtain a minimum in both overall examination score (OES) and overall continuous assessment score (OCAS) set by the University to obtain a Pass result. To be awarded a particular course grade, a student must meet the minimum CS set by the Award Committee.

Assignments

This course is designed to help you move easily from the required readings to the assignments and the examination. You are expected to apply information and techniques presented during the course when completing the assignments.

You must submit assignments to the e-submission in the OLE following the due dates stated on each assignment. The due dates can also be found on the Presentation Schedule. The self-tests or SAQs are, by definition, not part of your formal assessment, but you must complete them as you work through the blocks. They not only expose you to the types of problems you are required to complete for the assignments, but they also reflect the demands of the block objectives and are designed to help you understand and apply the principles covered in the blocks.

E-submission of Assignments: There are four assignments for this course. These are all assignment exercises. You are required to submit your assignments via e-submission in the OLE. You must submit the assignments on or before the corresponding due date. You can prepare your assignments using word processing software (e.g. Word) and then upload the pdf file to OLE. Or you can complete your assignments on paper and convert them to soft copy by scanning or taking pictures. The recommended format is pdf (the file size should be less than 10 MB).  

Your tutor will mark these assignments. Each assignment has a weighting of 10%.

How to do your assignments

For each assignment, first, read quickly through the description of the problem in the Assignment File. Make brief notes on what you believe are the key points raised. Next, carefully read the description two or three times while referring to your notes. Make sure that you have identified all the key points. Then, read the instructions that accompany the problem. These explain what you are required to do. Make sure you understand what is required and that your assignment provides what is required.

When you have completed the assignment, you should submit your assignment via the e-submission in the OLE. Make sure that each assignment is uploaded to the OLE before the due date. Marks may be deducted for work that is late without prior authorization. If, for any reason, you cannot complete your work on time, contact your tutor before the assignment is due. This is to discuss the possibility of an extension. Extensions will not be granted after the due date unless there are extremely exceptional circumstances.

You should use references other than your textbooks or work when researching the answers for your assignments. Make sure that you reference your work properly. If you do not, you commit plagiarism and will be penalized severely. Plagiarism is the theft of somebody else's work or ideas. This applies just as much to using the work of other students as it does to the authors of books. If you use somebody else's ideas in your work, give them credit for it. You do this by referencing. In the body of the work, this appears as (Stallings, 2000) for example. At the end of your assignment, list all of your references alphabetically in a section called 'References'. Include the full name, title, date and place of publication. For instance, one way to cite a reference is:

Stallings, W (2000) Computer Organization and Architecture (5th Edition), Upper Saddle River, NJ: Prentice Hall.

6.1 The course as a whole

The following table shows the amount of study time allocated to each of the blocks of the course.

How these overall times break down into study times for the individual parts of each block is described in each of the detailed block study guides that follow. Before starting to study each block, you should read the detailed study guide for that block to plan the use of your time effectively. The Presentation Schedule shows how the tutorials, short labs, and assignments relate to your study of the texts.

Study note — a domestic central heating system.

Twice in Block 1 (in Parts 1 and 5) and again in Block 6, the text authors have used a central heating system, either as an analogy to an electrical circuit or as an example of the application of electronics. Because the course was written in the U.K. where central heating systems are fitted into most homes, the authors assume familiarity with such systems that Hong Kong residents may not possess. Consequently, included below is a general description of a typical domestic central heating system. If you are already familiar with such systems, you will not need to read them. If you do need to read it, remember that it is not material that will ever be assessed in the continuous assessment or the examination. It is provided solely for clarification when reading the block texts.

In Britain, winters can be very cold, and energy must be used to provide heat to maintain a comfortable living environment inside the home. The most common way of providing this heat in Britain is the domestic central heating system, and the most common form of central heating uses natural gas as the source of energy.

The gas is burned in a boiler, where it raises the temperature of water to about 60°C. A local controller monitors the water temperature and switches the gas supply to the boiler on and off to maintain this water temperature. A pump circulates the water through the boiler and some radiators are distributed around the house. Each radiator is a thin hollow rectangle, perhaps 600 mm high by 2 m long, mounted on a wall, and about 50 mm away from it. When the hot water is pumped through it, the surface of the radiator becomes hot and heat is radiated from it (hence the name 'radiator') and also removed from it by convection air currents, so warming the room in which the radiator is placed. Each of the radiators is normally connected in parallel between a 'supply' hot water pipe from the boiler and the pipe returning the water to the boiler so that any one radiator can be manually turned off by closing a tap in its supply pipe without stopping the flow of water to the other radiators in the system.

As well as the local control of the gas consumption in the boiler, a temperature sensor (usually called a thermostat) detects the air temperature at some central point of the house and automatically switches the pump circulating the hot water on and off. When the temperature is lower than the required value, the pump is switched on. When the temperature reaches the required value, the pump is switched off. By this means, a comfortable temperature can automatically be maintained throughout the home.

In addition to these two control mechanisms, a central controller usually provides facilities for fixing the times at which the whole system switches itself on and off, for example, so that the heating switches on an hour before the occupants of the house wake up in the morning, so that it switches itself off 30 minutes before they go out to work, so that it switches on one hour before they return from work, and so that it automatically switches itself off 30 minutes before they go to bed at night. (Because the house 'stores' heat in the furniture, in the walls, and in the air contained within the house, the temperature falls quite slowly after the system is switched off, and switching the system off early can save a considerable amount of costly energy.) Such a central controller can also provide facilities for using different switching times at weekends, or for independently controlling the supply of heat to different areas of the house (for example, bedrooms might only be heated for one hour before bedtime).

The simple system shown in Figure 9 of Block 1, Part 5 (page 45) is an oversimplified system that is not representative of central heating systems in general but is adequate for the discussion of feedback systems presented there.

6.2 Block 1 (Introduction to signals and circuits) Study Guide

This block is scheduled to occupy about 7.5 weeks of your study time.

There are five parts in this block, and you are advised to study them in the order in which they are presented. You may find that some of the earlier parts, particularly Part 1, cover topics that you have studied before, in which case you may need to do no more than read them to refresh your memory.

Parts 1 and 2 are concerned with d.c. currents and voltages, so you will only be considering components such as batteries, resistors and lamps and the like. The practical work associated with Part 1 is fairly elementary and will take place during the first part of Short Lab 1. Please remember that there is more practical work to come in the course, and gaining familiarity with real circuits and components may be more important than you think. The use of a CAD package (OrCAD) to calculate circuit performance is almost certain to be new to you. It is something you will return to frequently throughout the course, so you need to become familiar with the package as early as possible, and to gain as much experience of using it as you can.

Some basic ideas concerning a.c. or varying currents and voltages are introduced in Parts 3, 4 and 5. Their function is to prepare you for the extensive theoretical and practical work associated with electronic circuits. Part 3 describes a.c. waveforms and the way they can be specified, and the practical work associated with this part, which occupies the remaining part of Short Lab 1, includes an introduction to the use of an oscilloscope and a signal generator. In Part 4, some additional components that are used with a.c. waveforms are described and explained, including capacitors, inductors, diodes and transformers. Transistors are also introduced, though they are not dealt with in any detail until Block 4. Part 5 explains some of the things you can do with them.

You can ignore Part 6 in Block 1 because it applies to the old T202 course only. However, if you are interested, you can read Sections 1–4 of Part 6.

The order of study and the approximate study time for each part of Block 1 is shown below. This assumes that the time that you spend studying the course is about 9 hours per week (on average) for the 34 weeks of the course, plus the time spent at weekend schools.

6.3 Block 3 (Digital principles) Study Guide

This block is scheduled to occupy about 13.5 weeks of your study time..

Part 1 introduces you to the concept of binary logic and shows you how a problem can be specified so that it can be finally implemented using electronic devices. Part 2 continues with this theme and develops the necessary skills for you to be able to carry out a complete combinational logic design. Part 3 introduces the topic of synchronous sequential logic circuits. It shows you how these circuits can be designed, using the knowledge that you already have about designing combinational logic circuits, because of the existence of specific types of memory devices. Part 4 deals with the interface between analogue and digital electronics. The supplementary readings will provide further information on selected logic circuits.

Finally, there are home computing exercises and short labs. The home computing exercises allow you to simulate and test the logic circuits that you have designed as part of your study of the block. The short lab experiments are based on Part 4 of the block and are therefore concerned with analogue-to-digital and digital-to-analogue conversion.

The order of study and the approximate study time for each part of the block is shown below.

6.4 Block 4 (Transistors and basic circuits) Study Guide

This block is scheduled to occupy about 7 weeks of your study time. Most of the students find this block is a difficult one and need a longer time to study it.

This block is about diodes and transistors: how they work and how they can be used in basic transistor circuits. There are three parts in total in the block: Part 1 (p-n junctions and transistors), Part 2 (Analogue transistor circuits) and Part 3 (Digital transistor circuits) in ELEC S222. In this course, you are only required to study Sections 1-2 of Part 2 and the remaining sections of Part 2 will be covered in the course ELEC S225 Analogue Circuits.

Part 1 (p-n junctions and transistors) is about how the devices work. It goes more deeply into the operation of devices than simply describing their properties, but it only provides enough explanation to enable you to cope sensibly with simple circuits. It does not, for example, give sufficient explanation to enable you to construct transistors or even fully understand how they are made. The explanations given are intended, for example, to enable you to calculate what changes in device characteristics to expect when you change the operating current or supply voltage of a device, or to enable you to look for causes of unsatisfactory performance in circuits that you have built.

Sections 1–2 of Part 2 (Analogue transistor circuits) is about the small-signal equivalent circuits of transistors.

Part 3 (Digital transistor circuits) is about the response times of different designs of switching circuits. It explains the causes of speed limitations in transistor switching circuits, as well as the meaning and cause of some other important performance parameters. These explanations should, for example, help you choose the kind of circuit to suit a particular application and to see why there are constraints on how circuits can be put together.

There are no home computing exercises or short labs associated with this block.

The order of study and the approximate study time for each part of the block is shown below.

6.5 Block 6 (Digital systems) Study Guide

This block is scheduled to occupy about 5 weeks of your study time.

Block 6 builds upon the ideas introduced in Block 3, Part 3.

Part 1 of the block is concerned with memory devices used for the storage and retrieval of data in digital systems. The starting point is the bistable circuit that can be used to store a single bit (binary digit) of data. The text then shows how much larger data storage systems can be built up from these fundamental building units, enabling the storage of many millions of bits of data. You will also learn about the implications of memory size on the associated circuitry needed to control the input and retrieval of data from memories.

In Part 2 you will see how the storage retrieval and manipulation of data in a large memory system can be managed by microprocessors and microcontrollers. Since this course is not primarily about computers and computing, the main aim is to introduce and illustrate the range of activities that a microprocessor or microcontroller can carry out. This will enable you to describe what is happening inside the controller when it is programmed to carry out a program of instructions to fulfil a well-defined task or function.

There are no home computing exercises or short labs associated with this block.

The approximate study time for each part of the block is as follows: