1. ECE 301 – Digital Electronics
Single-bit Adder Circuits
(Lecture #12)
The slides included herein were taken from the materials accompanying
Fundamentals of Logic Design, 6th Edition, by Roth and Kinney,
and were used with permission from Cengage Learning.

2. ECE 301 - Digital Electronics
The Half Adder (HA)
Fall 2010
ECE Digital Electronics

3. ECE 301 - Digital Electronics
The Half Adder
Sum
Carry
Fall 2010
ECE Digital Electronics

4. ECE 301 - Digital Electronics
The Half Adder A B
Sum
Carry 1
Truth Table
Fall 2010
ECE Digital Electronics

5. The Half Adder Given the truth table on the previous slide,
1. Derive the Boolean expressions for the sum and carry.
2. Draw the corresponding circuit diagram.
Fall 2010
ECE Digital Electronics

6. ECE 301 - Digital Electronics
The Full Adder (FA)
Fall 2010
ECE Digital Electronics

7. ECE 301 - Digital Electronics
The Full Adder
Carry-in
Carry-out
Sum
Fall 2010
ECE Digital Electronics

8. ECE 301 - Digital Electronics
The Full Adder A B
Cin
Sum
Cout 1
Truth Table
Fall 2010
ECE Digital Electronics

9. The Full Adder Given the truth table on the previous slide,
1. Derive the Boolean expressions for the sum and carry-out.
2. Draw the corresponding circuit diagram.
Fall 2010
ECE Digital Electronics

10. Design the Full Adder hierarchically, using 2 Half Adders 1 OR gate
Fall 2010
ECE Digital Electronics

11. ECE 301 - Digital Electronics
The Full Adder
Half Adder (ha2)
Cin
Sum B A
Cout
Half Adder (ha1)
Fall 2010
ECE Digital Electronics

12. ECE 301 - Digital Electronics
Questions?
Fall 2010
ECE Digital Electronics