Transcript Slide 1
Ch 1. Introduction
• Analog Signal
– Continuous voltage
– Unwanted noise
– Can’t transmit data at long distance
• Digital Signal
–
–
–
–
–
‘0’ &’1’, ‘False’ & ‘True’, ‘High’ & ‘Low’
Enables transmission of signals over a long distance
More secure
Lower electromagnetic interference
Enables Multi-directional transmission simultaneously
1.3 Digital Devices
• Gate
– The most basic digital devices
– Got there name from their function (AND, OR…)
– Gate has one or more inputs and produces output
that is function of current input values
INPUT
2 input AND gate
OUTPUT
A
B
Y
0
0
0
0
1
0
1
0
0
1
1
1
INPUT
2 input OR gate
OUTPUT
A
B
Y
0
0
0
0
1
1
1
0
1
1
1
1
1.4 Electronic Aspects of Digital Design
Logic Function
Electronic Function
• Noise Margin
– The voltage difference between the guaranteed output level
and the required input voltage of a logic gate
– In a real circuit, a gate’s output can be corrupted by this
much noise
1.5 Software Aspects of Digital Design
Software Tools
CAD
Schematic Diagram
HDLs
Text editors
Compilers
Synthesizers
Simulators
Test Benches
Timing Analyzers
Ex) Modelsim, Xilinx, Synplify, XST
• HDL
- Hardware Description Language
- 1980년대 초부터 미 국방성에서 사용시작
- 1981년 VHDL (VHSIC Hardware Description Language) 제안,
이후 IEEE 표준으로 채택
• HDL 이전
- Layout editor나 Schematic editor를 사용
- 작은 블록을 설계하고 큰 블록을 설계하는 Bottom-up 방식
- 회로의 규모가 커지고 복잡도가 증가함에 따라 한계 발생
• HDL 이후
- 알고리즘이나 기능 레벨에서 설계가 가능
- Top-down 방식
- 복잡한 회로의 설계 가능
1.6 Integrated Circuits
• IC (Integrated Circuit)
– Collection of one or more gates fabricated on a single silicon chip
– SSI (Small Scale IC) →MSI (Medium Scale IC) →LSI (Large Scale IC)
→ VLSI (Very Large Scale IC)→SoC (System on Chip)
→ NoC (Network on Chip)
– pad, die
Pin diagrams are used only for mechanical reference
1.7 Programmable Logic Devices
PLA (Programmable logic array) : Only two level structure (AND, OR)
PAL (Programmable array logic), PLD(Programmable logic device)
→CPLD(Complex PLD)→FPGA(Field-programmable gate array)
1.10 Digital-Design Levels
input
𝐖𝐡𝐞𝐧 𝑺 = 𝟎, 𝒁 = 𝑨
𝐖𝐡𝐞𝐧 𝑺 = 𝟏, 𝒁 = 𝑩
output
Turn on when ‘0’
output
input
𝒔
Turn on when ‘1’
𝐖𝐡𝐞𝐧 𝑺 = 𝟎, 𝒁 = 𝑨
𝐖𝐡𝐞𝐧 𝑺 = 𝟏, 𝒁 = 𝑩
2-input 4-bit MUX
Input : A and B (0~4bits)
Output : Z (0~4bits)
𝐖𝐡𝐞𝐧 𝑺 = 𝟎, 𝒁 = 𝑨
𝐖𝐡𝐞𝐧 𝑺 = 𝟏, 𝒁 = 𝑩
𝐖𝐡𝐞𝐧 𝑺 = 𝟎, 𝒁 = 𝑨
𝐖𝐡𝐞𝐧 𝑺 = 𝟏, 𝒁 = 𝑩
Conditional operator
𝒁 = 𝐂𝐨𝐧𝐝𝐢𝐭𝐢𝐨𝐧 ? 𝐓𝐫𝐮𝐞: 𝐅𝐚𝐥𝐬𝐞