I need full 4 bits adder circut with small project

how to connect full adder

I need full 4 bits adder circuit with small project
like full adder work manner
I'm bigenner , I appreciate any help



thanks in advance

Hello Heartstation,
This topic has been posted more than once.

Your problem can be solved easily indeed.
All you have to do is first build a 1 - bit full adder and connect 4 1- bit full adders to make a 4 - bit full adder. Connect the Carry_OUT output of the adder to the next adder's Carry_IN input.

The following is a guide to make a 1 - bit full adder. You can implement it in two ways using a Decoder - OR combination ( the one being described below) or gate level implementation (make the eqaution out of the minterms given below).

A, B are your addends
C = Carry Input
S = Sum Output
Y = Carry Out

1.) The Truth Table Looks like this:
A B C : S Y
0 0 0 : 0 0
0 0 1 : 1 0
0 1 0 : 1 0
0 1 1 : 0 1
1 0 0 : 1 0
1 0 1 : 0 1
1 1 0 : 0 1
1 1 1 : 1 1

DECODER - OR implementation

2.) Connect your Inputs (ABC) to 3 -to -8 DECODER inputs in that order ABC.

3.) I am not sure if there is a positive logic output decoder. I used once the 74LS138 3 -to -8 decoder but it is a negative logic output. If you can find a positive logic out put 3 - to - 8 decoder then it is possible to implement your problem. but otherwise you need inverters.

4.) You didn't say how many inputs are there in your OR gate so I assume that this its input is variable.

5.) Basically connect the outputs of the decoder to the inputs of the 4 - input OR gate using the following equation.

S (Sum) = Σm(1,2,4,7)
Y (Carry Out) = Σ (3,5,6,7)



Gate Level Implementation
S = A xor B xor C
Y = AB + C (A xor B)

Your problem can be solved easily indeed. All you have to do is first build a 1 - bit full adder and connect 4 1- bit full adders to make a 4 - bit full adder. Connect the Carry_OUT output of the adder to the next adder's Carry_IN input.