Transcript NOT and NOR Gates

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Digital Logic Structures:
Chapter 3
COMP 2610
Dr. James Money
COMP 2610
Logic Gates

One level up from the transistor is a logic
gate

We use individual MOS transistors to
construct our basic logic structures

We will consider AND, OR, and NOT gates
The NOT Gate (Inverter)

To construct a NOT gate, we need
–
One n-type transistor
–
One p-type transistor

These are connected together to obtain the
NOT gate

This is sometimes called an inverter
The NOT Gate (Inverter)
2.9 Volts
In
Out
0 V 2.9 V
2.9 V
0 Volts
0V
In
Out
0
1
1
0
The NOT Gate (Inverter)
OR and NOR Gates
A
B
C
0V
0V
2.9 V
0V
2.9 V
0V
2.9 V
0V
0V
2.9 V
2.9 V
0V
OR and NOR Gates
A
B
C = A NOR B
0
0
1
0
1
0
1
0
0
1
1
0
OR and NOR Gates

How to we obtain the OR gate now?

We chain the NOT gate to the end of the
NOR gate

NOT (NOR) = OR

We do this b/c it is cheaper to produce NOT
type gates versus regular ones
OR and NOR Gates
OR Gate