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Design full adder using decoder with active high output

written 4.7 years ago by teamques10 ★ 70k

•   modified 4.7 years ago

digital electronics

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written 4.7 years ago by teamques10 ★ 70k

modified 3.6 years ago by phenjoisilab • 0

The inuts of a full adder are threee and the outputs of a full adder are two (i.e. Sum and Carry).

The decoder circuit has 'n' inputs and '2n' outputs.

The truth table of a full adder:

Input	Output
X	Y	Cin	Cout	Sum
0	0	0	0	0
0	0	1	0	1
0	1	0	0	1
0	1	1	1	0
1	0	0	0	1
1	0	1	1	0
1	1	0	1	0
1	1	1	1	1

 The truth table of a 3x8 decoder

X	Y	Z	m7	m6	m5	m4	m3	m2	m1	m0
0	0	0	0	0	0	0	0	0	0	1
0	0	1	0	0	0	0	0	0	1	0
0	1	0	0	0	0	0	0	1	0	0
0	1	1	0	0	0	0	1	0	0	0
1	0	0	0	0	0	1	0	0	0	0
1	0	1	0	0	1	0	0	0	0	0
1	1	0	0	1	0	0	0	0	0	0
1	1	1	1	0	0	0	0	0	0	0

 Sum=m1+m2+m4+m7

Carryout=m3+m5+m6+m7

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