Logic Circuit Design

Teacher ： Wei-Ru Lai ( 賴薇如 )wrlai@saturn.yzu.edu.tw

Office: 2307 Telephone:2431

Lab: 3412 Telephone:2414-35

Text Book and Reference

Textbook– Charles H. Roth, Jr., Fundamentals of Logic

Design, 5th edition, West Publishing Co., 1992.

Reference book– A First Course in Digital System Design, An

Integrated Approach, John P. Uyemura, Georgia Institute of Technology. Books/Cole Publishing Company

Course Time

B 班– Monday 8 (3:10 - 4:00) – Friday 1,2 (8:10 - 10:00)

Classroom: 2008 Office Hour: Wednesday 13:10-14:30

3412R

Teacher Assistant

周旭陵 (Nash), 彭健倫 (Artist)– 3412R – Tel: 2415 – 35

You can get some papers for homework at 3412 Room.

Please use A4-size papers for your homework.

Web Site

IP address: 140.138.137.171 or pcs.eed.yzu.edu.tw– Handout, old examination questions

Portal– Homework and solution– Discussion – Information, ex: Time and place of quiz

It’s necessary to watch these web sites.

Requirements for Class

Take your textbook. Take notes in class. Don’s chat in class. Close your handset. Ask questions if you don’t understand. To hand in an assignment in time.

Esteem your teachers, TAs and classmates.

Change Your Mindset

Adapt yourself to the new environments, new teachers, and new teaching methods.

Read the textbook written in English. You should spend a lot of times in this course. Do your homework by yourself. Find your favorite department. Try to achieve the basic requirements of our

departments.

Evaluation

Class Presentation (10%) Homework (2%*10=20%) Quizzes (7%*4=28%)

– 10/3, 10/24, 11/28,12/19 (13:00-14:00)

Mid exam (20%) 11/9 Final exam (22%) 1/11

Your Background

Do you know...– Analog ( 類比 ), digital ( 數位 )– Bit (=0/1), byte (=8 bits)– 2-state signal – 0/1 – binary number – Diode, transistor, TTL, CMOS...– System design, logic design, circuit design

Analog vs. Digital

Analog system– The physical quantities or signals may vary continuously

over a specified range.

Digital system– The physical quantities or signals can assume only

discrete values.

0 1 2 3 3 0 3 2 3 2 0...

Analog Signals

Nature signals are analog. Analog signals: the quantities may vary

continuously over a specified range. Distortion( 失真 ): the wave is distorted due

to attenuation or noise. If an analog signal is distorted, it is difficult

to regenerate a original one.

Digital Signals

Think the nature signal as 0 and 1. Digitalize（數位化）： transfer the nature signal to a series of 0s and 1s.

– Binary system: only 0 &1

– Ex: 510=01012

logic 0

logic 1

volt

1

2

3

4

5

0

Unknown

0 1 0 1

Analog or Digital? (1/2)

The differences between analog systems and digital systems are the idea to view and process the data.– Analog view: every amplitude is meaningful in

every moment. Every qualify between 0-5V is meaningful.

– Digital view: only 0 & 1

Analog or Digital? (2/2)

Question: Which one is an analog signal? Which one is a digital signal?– human voice, electromagnetic wave of handset, ,

data in CD, voice sent by handset, watercolor, a negative of photo, data in digital camera

Question: What are the advantages and disadvantages to store photos (or send audio) by the analog (or digital) method?

Advantages of Digital Signals

It is easy to distinguish between 0 and 1 even though the digital signal is distorted.

Distorted digital signal can be regenerated. Special encoding schemes is used for error

detection or error correction Encryption can prevent from

eavesdropping. 01010011

odd parity0 1 0 1

Digital System

A digital system is an electronic network that “process” information using only digits to implement calculations and operations.

– Ex: answer machine, video game, CD, computer...

1. Transfer analog signals to digital signals.

2. Perform operations by 0 and 1.

3. Transfer the results to analog signals.

Accuracy

Operation in analog systems: the error (i.e., distortion) will be accumulated. – Ex: to compute 6*100. These is an error 0.1.

5.9*100=590

Operation in digital systems: the distorted signal can be regenerated and the error will not be accumulated.– Ex: 1102*11001002=1001011002

– Digital systems are capable of greater accuracy.

Audio System

Analog data

Digital data

Sampling ( 取樣 )

To achieve some discrete values from the originally continuous signals is called as sampling.

These discrete values are called discrete signal（離散信號） or samples （取樣點） .

Sampling rate （取樣頻率） is the times to achieve discrete signals per second.– Ex: If we get 8000 samples per second, the sampling

rate is 8000Hz.

Sampling Theorem ( 取樣定理 )

Sampling Theorem （取樣定理） or Nyquist Theorem ： Sampling rate must be twice (or more) of the original data rates.

For example, the frequency of human voice is about 300-3400Hz. Then the sampling rate in PSTN is 8000Hz.

Quantization ( 量化 )

If the length of 0/1 bit stream is finite, the number of amplitude quantities that can be represented by these bit streams （ referred to quantization level 量化準位） is finite.

To find a relative level for each sample is called quantization （量化）。

The distance between the sample and its quantization level is called quantization error（量化誤差）。

Coding ( 編碼 )

Coding （編碼）： use a series of 0s and 1s to represent every quantization level 。

Pulse Code Modulation （ PCM ） used in PSTN is 8-bit coding and 256 quantization level.

The sampling rate is 8KHz. 64,000 bits are sent per second. That is, the data rate is 64,000bps 。

Questions

How to store 0 and 1 by physical devices? How to perform the operations of 0 and 1

by these physical devices? – Ex: How to do “1+1=10”?– What is the basic physical devices? – What is the basic digital operation? – Answer: AND, OR, NOT, NOR, NAND and

XOR logic gates.

Switching Devices (1/2)

Two-state devices: the output can assume only two different discrete values.– Example of switching devices: relays, diodes,

transistors, CMOS.

logic 0

logic 1

volt

1

2

3

4

5

0

On

Off

Unknown

Gate

Source

Drain

Transistor

Switching Devices (2/2)

A B F

0 0 +V 0 +V +V +V 0 +V +V +V 0

Connecting several switching devices may perform some operations of 0 and 1. That is, you have created a binary system 。

We can use binary system to present the circuits made by switching devices.

NAND Gate

Circuit Design

Circuit design involves specifying the interconnection of specific components such as resistors, diodes, and transistors to form a gate, flip-flop, or other logic building block.

To design Integrated circuit (IC) Electronics, VLSI (Very Large Scale

Integrated circuits), Practicum of VLSI

Representation of AND, OR, XOR, and NOT Gates (1/2)

Representation of AND, OR, XOR, and NOT Gates (2/2)

Logic Design

Logic design involves determining how to interconnect basic logic building blocks to perform a specific function.– Block: logic gates, latches, flip-flops– Larger blocks: addition, counter, memory, multiplexer, CPLD, FPGA

A B F

0 0 1 0 1 1 1 0 0 1 1 1

S-R Latch

To store 0 or 1. Use OR/NOT gates to construct a larger component!

LS

R

S

R

Q

P

Q

P

A new block

Half Adder

A + B = Sum with a Carry– Sum = A XOR B– Carry = A AND B

A

BCarry

SumXOR

AND

Half Adder

A B Carry Sum

0 0 0 0 0 1 0 1 1 0 0 1 1 1 1 0

HAA

B Carry

Sum

Theory in the Logic Design

“Logic Design” tells us the theory necessary for understanding the logic design process.

Boolean algebra: the binary number system used in the logic design.

Technologies of digital systems are improved fast. However, its background theory is never changed.

Combinational Networks

The output values depend only on the present value of the inputs and not on past values.

Sequential Networks

The outputs depend on the present value of the inputs and past input values.

Basic memory elements: flip-flops feedbackmemory

Switching Circuits

Both combinational networks and sequential networks are called as switching circuits.

Computer Science, Practicum of Digital Circuit

System Design

System design involves breaking the overall system into subsystems and specifying the characteristics of each subsystem.•Subsystem of computer includes memory units, arithmetic units, input-output units and control units.

Categories of Designs

The design of digital systems may be divided roughly into three parts– Circuit design, logic design, system design

Easy to design a digital system!– Basic block Small blocks Large blocks A

large system

Microcomputer System ， Practicum of Microcomputer System, Digital System Design, Computer Architecture

Need to Learn for Logic Design

Number systems Boolean algebra Logic gates Combinational logic circuit design Multiplexers, decorders, and PLD Flip-Flops Sequential logic circuit design VLSI

Conclusions

This is an interesting course. Hope you like it.