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    What Is A Full Adder?: Block Diagram

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    A full adder is a digital circuit that performs addition of three binary bits. It takes two input bits (A and B) and a carry bit (Cin) and produces a sum bit and a carry out bit (Cout). The full adder can be implemented using logic gates by breaking it down into half adders and an OR gate. It is described using a truth table and Verilog code is provided to design a full adder circuit and test bench.

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    What Is A Full Adder?: Block Diagram

    Uploaded by

    Abcd
    55 views5 pages
    A full adder is a digital circuit that performs addition of three binary bits. It takes two input bits (A and B) and a carry bit (Cin) and produces a sum bit and a carry out bit (Cout). The full adder can be implemented using logic gates by breaking it down into half adders and an OR gate. It is described using a truth table and Verilog code is provided to design a full adder circuit and test bench.

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    What is a full adder

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    A full adder is a digital circuit that performs addition of three binary bits. It takes two input bits (A and B) and a carry bit (Cin) and produces a sum bit and a carry out bit (Cout). The full adder can be implemented using logic gates by breaking it down into half adders and an OR gate. It is described using a truth table and Verilog code is provided to design a full adder circuit and test bench.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    55 views5 pages

    What Is A Full Adder?: Block Diagram

    Uploaded by

    Abcd
    A full adder is a digital circuit that performs addition of three binary bits. It takes two input bits (A and B) and a carry bit (Cin) and produces a sum bit and a carry out bit (Cout). The full adder can be implemented using logic gates by breaking it down into half adders and an OR gate. It is described using a truth table and Verilog code is provided to design a full adder circuit and test bench.

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    © All Rights Reserved
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    Download as docx, pdf, or txt
    of 5

    What is a full adder?

    The full adder is a digital circuit that performs the addition of three numbers. It
    is implemented using logic gates. A one-bit full adder adds three one-bit
    binary numbers (two input bits, mostly A and B, and one carry bit Cin being
    carried forward from previous addition) and outputs a sum and a carry bit.
    BLOCK DIAGRAM

    the Boolean Logical Functions for the Circuit


    S = A ⊕ B ⊕ Cin
    Cout = A.B + B.C + C.A
    OR
    Cout = A & B | (A^B) & Cin

    Logic Diagram of Full Adder Circuit


    Truth Table for Full Adder:
    A B Cin SUM (S) CARRY (Cout)

    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
    Design the RTL Schematic (Gate Level Diagram) for the Circuit

    Hardware Schematic for full adder


    This is the hardware schematic for the design code that has been executed.

    RTL Schematic for Full Adder Circuit


    Write the HDL module and Test bench program for the Circuit

    Full Adder using Verilog HDL


    step by step as follows.
    Step-1/2 :
    Concept –  
    Full Adder is a digital combinational Circuit which is having three input a, b and cin and
    two output sum and cout. above Truth Table to do the functionality
    Step-3 :
    Verilog HDL code for Full Adder (Design Part) –
    // Code your design : Full Adder
    module full_add(a,b,cin,sum,cout);
    input a,b,cin;
    output sum,cout;
    wire x,y,z;

    // instantiate building blocks of full adder


    half_add h1(.a(a),.b(b),.s(x),.c(y));
    half_add h2(.a(x),.b(cin),.s(sum),.c(z));
    or o1(cout,y,z);
    endmodule : full_add

    // code your half adder design


    module half_add(a,b,s,c);
    input a,b;
    output s,c;

    // gate level design of half adder


    xor x1(s,a,b);
    and a1(c,a,b);
    endmodule :half_add
    Step-4 :
    Test bench –
    // Code your testbench here
    module full_add_tb;
    reg a,b,cin;
    wire sum,cout;

    // instantiate the DUT block


    full_add f1(.a(a),.b(b),.cin(cin),.sum(sum),.cout(cout));

    // this particular line is added to dump the file on online simulator


    initial begin $dumpfile("full_tb.vcd");$dumpvars(); end

    // insert all the inputs


    initial begin a=1'b1; #4; a=1'b0;#10 $stop();end
    initial begin b=1'b1; forever #2 b=~b;end
    initial begin cin=1'b1;forever #1 cin=~cin; #10 $stop();end

    // monitor all the input and output ports at times


    // when any of the input changes its state

    initial begin $monitor(" time=%0d A=%b B=%b


    Cin=%b Sum=%b Cout=%b",
    $time,a,b,cin,sum,cout);end
    endmodule : full_add_tb
    Step-5 :
    Expected Output –
    time=0 A=1 B=1 Cin=1 Sum=1 Cout=1
    time=1 A=1 B=1 Cin=0 Sum=0 Cout=1
    time=2 A=1 B=0 Cin=1 Sum=0 Cout=1
    time=3 A=1 B=0 Cin=0 Sum=1 Cout=0
    time=4 A=0 B=1 Cin=1 Sum=0 Cout=1
    time=5 A=0 B=1 Cin=0 Sum=1 Cout=0
    time=6 A=0 B=0 Cin=1 Sum=1 Cout=0
    time=7 A=0 B=0 Cin=0 Sum=0 Cout=0
    time=8 A=0 B=1 Cin=1 Sum=0 Cout=1
    time=9 A=0 B=1 Cin=0 Sum=1 Cout=0
    time=10 A=0 B=0 Cin=1 Sum=1 Cout=0
    time=11 A=0 B=0 Cin=0 Sum=0 Cout=0
    time=12 A=0 B=1 Cin=1 Sum=0 Cout=1
    time=13 A=0 B=1 Cin=0 Sum=1 Cout=0

    Draw the CMOS Logic Circuits

    CMOS circuit for full adder

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