1. 4 bit Full Adder Layout and Analysis using Lasi and WinSpice
Final Exam Project
4 bit Full Adder Layout and Analysis using Lasi and WinSpice

2. Assignment Objectives
Do a hierarchal layout of a half adder, full adder and 4 bit adder using LASI, then simulate the circuit using SPICE to make sure that the design will work.

3. Overview Hierarchal Layout design is done using Lasi.
N3X2, P3X2, NAND, XOR, Half-Adder, Full-Adder and 4 bit Full Adder layouts are made in hierarchal sfashion using bottom up approach.
Each Cell is analyzed by using Winspice3 .CIR file created by Lasi.

4. P3X2 (Rank 1)Cell- Standard cell from Lasi Library

5. N3X2 (Rank 2) Cell -Standard cell from Lasi Library

6. INVERTER (Cont’d) Inverter cell has Rank 2.
Inverter cell is made using P3X2 and N3X2 cell.
It is used to provide A’ and B’ for XOR input and NAND input to make OR gate.Also it is used at output of a NAND to make AND.

7. INVERTER

8. NAND (Cont’d) NAND cell has rank 2.
It is used to make AND gate and OR gate.

9. NAND

10. XOR (Cont’d) XOR cell has Rank 2.
It is is made to provide sum of Half Adder.
It is little different than regular XOR because it requires four inputs A, A’, B, and B’.
By designing in with four inputs we simplify design and reduced transistors.

11. XOR

12. Half-Adder (Cont’d) Half-Adder has rank 3.
It is designed using INVERTER, NAND and XOR gate.
Sum = AB’ + B’A.
Carry = AB.

13. Half-Adder

14. Full-Adder (Cont’d) It has rank 4.
Full adder is made using two HALF-ADDER , 2 Inverter and a NAND gate.
S1 = HA(A,B)
Sum = HA(S1,Carry In)
Carry = OR(Carry 1,Carry 2)

15. Full-Adder

16. 4 Bit Full Adder (Cont’d)
It has rank 5.
It is made using four 1 bit Full-Adder.
First Full-Adder has Carry in 0.
4th Carry out is Final Carry out of 4 bit Full-Adder.

17. 4 Bit Full Adder

18. SPICE SIMULATION Each cell is compiled using LasiCkt.
Generate .CIR files used in WinSpice3 for simulation of circuit.
Every analyzed signal is offset by 6V to see each signal properly.

19. INVERTER Simulation (Cont’d)
Next slide shows screen capture of Inverter simulation.
A_ is output of signal input signal A.

20. INVERTER Simulation

21. NAND Simulation (Cont’d)
Next slide show simulation of NAND gate.
AB_ is output of NAND gate.
11,10,01,00 signals analyzed.

22. NAND Simulation

23. XOR Simulation (Cont’d)
Next slide show simulation of XOR gate.
AXORB is output of XOR gate.
11,10,01,00 signals analyzed.
It is Sum of Half-Adder.

24. XOR Simulation

25. Half-Adder Simulation (Cont’d)
Next slide show simulation of Half-Adder gate.
S is Sum and C is carry.
11,10,01,00 signals analyzed.

26. Half-Adder Simulation

27. Full-Adder Simulation(Cont’d)
Next slide show simulation of full adder.
All the combination from 000 to 111 is used as Cin, B and A inputs.

28. Full-Adder Simulation

29. 4 Bit Full Adder Simulation (Cont’d)
Next four slides shows simulation of 4 bit Full Adder.
Individual plot used each inputs for proper demonstration.
VN4 is Carry out 1.
VN5 is Carry out 2.
VN6 is Carry out 3.

30. 4 Bit Full Adder Simulation- A0+B0 (Cont’d)

31. 4 Bit Full Adder Simulation- A1+B1 (Cont’d)

32. 4 Bit Full Adder Simulation- A2+B2 (Cont’d)

33. 4 Bit Full Adder Simulation- A3+B3 (Cont’d)

34. Related Documents
Included floppy contains two directories LASI and CIR.
LASI Directory Contains all the Layout files and other required files to open layouts in LASI .
To open LASI Layout files create shortcut of LASI executable file, and change the “Start in” option through properties to A:\ LASI \.
Circuit simulation .CIR files are located in CIR directories.