Pertemuan:6 (Adder : Combinational Logic Design)

11/02/2013 02:09:00 PM (Basic) Digital Technique 0 Comments

In this section, the discusion is about :

Binary Addition
– Half Adder
– Full Adder
– Ripple Carry Adder
– Carry Lookahead Adder
Decimal Addition (Section 3.12)
– BCD Adder

1-bit Adder:
• Performs the addition of two binary bits.
• Four possible operations:
– 0+0=0
– 0+1=1
– 1+0=1
– 1+1=10
• Circuit implementation requires 2 outputs; one to indicate the sum and another to indicate the carry.

Half-bit Adder:
Performs 1-bit addition.
• Inputs: A0, B0
• Outputs: S0, C1

Index indicates significance,
A0 B0 S0 C1
0 0 0 0
0 1 1 0

Truth Table 0 is for LSB and 1 is for the next higher significant bit.
Boolean equations:
– S0 = A0B0’+A0’B0 = A0 Å B0
– C1 = A0B0

Full Adder
 -Full adder (for higher-order bit addition)
 -Combinational circuit that performs the additions of 3 bits (two bits and a carry-in bit)


You can download full chapter from this link
BDT06-Combinational Logic Design