This document discusses CMOS VLSI design and MOS transistors. It introduces MOS transistors as the basic building blocks of integrated circuits and describes their four terminals - source, gate, drain, and body. It explains how doping silicon with group III or V elements creates n-type or p-type semiconductors and how applying different voltages to the gate controls the flow of current from source to drain, allowing MOS transistors to function as electrically controlled switches. The document presents the three operating regions for MOS transistors - cutoff, linear, and saturation - and how their I-V characteristics change based on the voltages applied to each terminal.

1. CMOS VLSI
Digital Design Slide 1
CMOS VLSI DESIGN
MOS Transistor Theory

2. CMOS VLSI
Introduction
 Integrated circuits
 Moore’s law
 Transistors
Digital Design Slide 2

3. CMOS VLSI
MOS Transistors
Digital Design Slide 3

4. CMOS VLSI
Digital Design Slide 4
Dopants
 Silicon is a semiconductor
 Pure silicon has no free carriers and conducts poorly
 Adding dopants increases the conductivity
 Group V: extra electron (n-type)
 Group III: missing electron, called hole (p-type)
As Si
Si
Si Si
Si
Si Si
Si
B Si
Si
Si Si
Si
Si Si
Si
-
+
+
-

5. CMOS VLSI
MOS Transistor
Digital Design Slide 5
4 Terminal device
• Source
• Gate
• Drain
• Body

6. CMOS VLSI
n-MOS operation
Digital Design Slide 6

7. CMOS VLSI
Digital Design Slide 7

8. CMOS VLSI
Transistor operating Region
Digital Design Slide 8

9. CMOS VLSI
Terminal Voltages
Digital Design Slide 9

10. CMOS VLSI
nMOS Cutoff
Digital Design Slide 10

11. CMOS VLSI
nMOS Linear
Digital Design Slide 11

12. CMOS VLSI
nMOS Saturation
Digital Design Slide 12

13. CMOS VLSI
nMOS I-V summary
Digital Design Slide 13

14. CMOS VLSI
Digital Design Slide 14
Transistors as Switches
 We can view MOS transistors as electrically
controlled switches
 Voltage at gate controls path from source to drain
g
s
d
g = 0
s
d
g = 1
s
d
g
s
d
s
d
s
d
nMOS
pMOS
OFF
ON
ON
OFF

15. CMOS VLSI
Digital Design Slide 15
CMOS Inverter
A Y
0
1
VDD
A Y
GND
A Y