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### Chap1

1. 1. DIGITAL ELECTRONICS (BEL 20303) Section 5 & 6
2. 2. PERSONAL DETAILS Name: Nur Ilyani Ramli Room: Block C15, Room 17 Contact No: 013-4549494 Email: ilyani@uthm.edu.my
3. 3. CHAPTER 1 INTRO TO DIGITAL SYSTEM 1. 2. 3. 4. 5. 6. Numerical Representation Digital & Analog Systems Advantages of Digital Techniques Limitation of Digital Techniques Overcoming the limitation of an analog world TTL and CMOS technology (Assignment 1)
4. 4. Learning Outcomes At the end of this chapter, you must be able to: 1. Distinguish between analog & digital representations 2. State the advantages and disadvantages of digital techniques compared with analog 3. Appreciate the need for ADCs and DACs 4 of 28
5. 5. 1. Numerical Representations - Most naturally occurring physical quantities in our world are analog in nature. - Quantities are measured, monitored, recorded, manipulated arithmetically, observed in most physical systems. - Important when dealing with quantities – To represent their values efficiently and accurately – 2 ways to represent them: 1) ANALOG representation 2) DIGITAL representation 5 of 28
6. 6. Analog Representation Represent a quantity by a continuously variable Characteristic of analog quantities – They vary over a continuous range of values Example – 1) Speedometer – 2) Thermometer Use a mechanical means ⇒ In electrical mean, the measured/processed physical quantity is converted to a proportional electrical signal (V or I) → used by the system for display, processing or control purposes 6 of 28
7. 7. Digital Representation Represent a quantity by a symbol, called digits. Characteristic of digital quantities – They varied in discrete steps Example 1) Digital Clock 2) Digital weighting scale 7 of 28
8. 8. Digital Number Systems There are many numbering systems used in digital technology. – Decimal ⇒ most familiar to us – Binary – Octal – Hexadecimal 8 of 28
9. 9. 1.2 Digital & Analog Systems ANALOG SYSTEM Devices that manipulate physical quantities that are represented in analog form. Example: magnetic tape recording and playback equipment DIGITAL SYSTEM Combination of devices designed to manipulate logical information or physical quantities that are represented in digital form. Example: digital calculator 9 of 28
10. 10. Example 1: Tape During playback, the ferromagnetic material in the tape head is magnetized as the magnetic tape passes. Then, the magnetic field penetrates a coil of wire which is wrapped around it. Change in magnetic field will induce a voltage in the coil according to Faraday's law. This induced voltage forms an electrical image of the signal which is recorded on the tape. Source: http://hyperphysics.phy-astr.gsu.edu/HBASE/Audio/tape.html#c4 10 of 28
11. 11. Example 2: Computer All the stored and processed data are in binary form. Why ? 11 of 28
12. 12. Example 3: CD CD player: digital and analog parts co-exist together (source: How Stuff Works website) 12 of 28
13. 13. 1.3 Advantages of Digital Techniques 1. Digital systems are easier to design 2. Information storage is easy 3. Accuracy & precision are easier to maintain throughout the system 4. Operation can be programmed 5. Digital circuits are less affected by noise 6. Digital circuitry can be fabricated on IC chips 13 of 28
14. 14. 1.4 Disadvantages of Digital Techniques 1. The real world is analogue 2. Processing digitised signals takes time 3. Digital circuits use more energy than analogue circuits & produce more heat 4. Digital circuits are made from analogue components – must make sure the digital behaviour is not affected by the analogue 5. Digital circuits are sometimes more expensive (in small quantity) 14 of 28
15. 15. 1.5 Digital Systems Overcome the Drawback of Analog Systems When dealing with analogue inputs and outputs, four steps must be followed 1. Convert the physical variable to an electrical signal (analogue) 2. Convert the electrical (analogue) signal into digital form ⇒ ADC (Analogue Digital Converter) 3. Process (operate on) the digital information 4. Convert the digital outputs back to real-world analogue form ⇒ DAC (Digital Analogue Converter) 15 of 28
16. 16. DIGITAL Example: Block diagram for a digital temperature control system 16 of 28
17. 17. Reference Thomas L. Floyd, Digital Fundamentals (10th edition), Pearson, 2009 Ronald J. Tocci, Neal S. Widmer & Gregory L. Moss, Digital Systems: Principles and Applications (11th edition), Pearson, 2011 17 of 28
18. 18. Group Assignment 1 Prepare a one page work describing TTL or CMOS Technology. 1- Explain current TTL/CMOS technology in general. 2- Advantage and disadvantage of TTL/CMOS. 3- Application. Dateline: Tuesday, 17 September 2013 18 of 28