Design & Implement FULLADDER
AIM:To Design & Implement FULLADDER program using Verilog HDL.
Objectives: Students will learn the various types of programming models like Dataflow, Structural and Behavioural .
TOOL:Xilinx ISE 9.2i Version
FAMILY 
SPARTAN 3 
Device 
XC3S400 
Package 
PQ208 
Speed 
4/5 
Synthesis 
XST(VERILOG/VHDL) 
Simulator 
ISE Simulator 
Architecture:
Truth Table:
A 
B 
C_in 
C_out 
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 
SOURCE CODE:
Dataflow Modeling:
module fulladddataflow(a, b, c, sum, carry);
input a;
input b;
input c;
output sum;
output carry;
assign#2 p=a&b;
assign#2 q=b&c;
assign#2 r=c&a;
assign#4 sum=a^b^c;
assign#4carry =(p1  p2)  p3;
Behavioral Modeling:
module fuladbehavioral(a, b, c, sum, carry);
input a;
input b;
input c;
output sum;
output carry;
reg sum,carry;
reg p1,p2,p3;
always @ (a or b or c) begin
sum = (a^b)^c;
p1=a & b;
p2=b & c;
p3=a & c;
carry=(p1  p2)  p3;
end
endmodule
Structural Modeling:
module fulladder(s,co,a,b,cin);
input a,b,cin;
output s,co;
wire t1,t2,t3;
xor x1 (t1,a,b);
xor x2 (s,t1,cin);
and x3 (t2,a,b);
and x4 (t3,t1,cin);
or x5 (co,t2,t3);
endmodule
Test Bench:
module fulladdertb();
reg a,b,cin;
wire s,co;
fulladder f1 (s,co,a,b,cin);
initial begin
{a,b,cin}=3'b000;
End
always #40 a=~a;
always #20 b=~b;
always #10 cin=~cin;
initial #80 $stop;
endmodule
SIMULATED WAVEFORMS:
RTL SCHEMATIC:
SYNTHESIS REPORT:
TIMING REPORT:
DEVICE UTILIZATION SUMMARY:
SYNTHESIS DIAGRAM:
CONCLUSION:
The Full adder was designed using Verilog HDL & implemented in FPGA Spartan 3 kit.
Viva Questions
1. Why is NAND gate preferred over NOR gate for fabrication?
2. What is Body Effect?
3. Why is the substrate in NMOS connected to Ground and in PMOS to VDD?
4. What is the fundamental difference between a MOSFET and BJT?
5. What is the disadvantage with carry chain?
6. What is the purpose of guard rings?
7. List any two nonsynthesizable verilog statements.
8. What is the difference between Spartan 3E and Vertex FPGA.
9. What is the number of NAND gates required to implement a 3bit full adder?
10. What is the number of NOR gates required to implement a 3bit full adder?
Outcomes: The outcome of this program is know the difference between the three modeling styles and when to use and where is it suitable.

UpdatedNov 28, 2021

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