Karnaugh
What are Karnaugh Maps?
A simpler way †o handle mos† (bu† no†
all) jobs of mani ula†in logic functions.
Karcaugh Advantages
• Minimization can be done more sys†ema†ically
• Much simpler †o find minimum solutions
• Easier †o see wha† is happening (graphical)
Almost always used instead
of boolean minimization.
2-bi† Gray
Code
00
01
11
10
Gray Codes
• Gray code is a binary value encoding in which
adjacen† values only differ by one bi†
F = A’
F=B
Key idea:
Gray code adjacency allows use of
simplification theorems
A B
0 0
O 0
Truth Table Adjacencies
These are adjacent in a9naycode sense -
†hey differ by 1bi†
We can apply XY + XY’ = X
A'B’ + A'B = A’(B'+B) A’(1) = A
Some idea:
A'B + AB = B
Problem:
Physical adjacency in †ruth †abIe does
not indicate gray code adjacency
2-Variable Karnaugh
A-0, B—0
A-0, B-1
A=1, B=0
A-1, B-1
A differen† way †o draw a †ru†h †abIe: by folding i†
A
0 1
0 1 0
‹ 0
0 0
Karnaugh
• In a K-map, physical adjacency does imply
gray code adjacency
A
B
F =A’B’ + A'B = A’
B 0 1
1
F = A'B + AB B
A B F
0 0 1
0 1 1
1 0 0
1 1 0
2-Variable Karnaugh
A B F
0 0 1
0 1 1
1 0 0
1 1
,
0
2-Variable Karnaugh
A
B 0 1
0
A B F
0 0 1
0 1 1
1 0 0
1 1
,
0
2-Variable Karnaugh
A
0 1
1
1
A B F
0 0 1
0 1 1
1 0 0
1 1
,
0
- 0
*0
2-Variable Karnaugh
A
B 0 1
A B F
0 0 1
0 1 1
1 0 0
1 1
,
0
2-Variable Karnaugh
A
B 0 1
1 0
1 0
0
1
F = A'B’ + A'B = A’
A B F
0 0 1
0 1 1
1 0 0
1 1
,
0
0
0
2-Variable Karnaugh
A
B 0 1
A = 0
F = A’
A B F
0 0 0
0 1 1
1 0 1
1 1 1
Another Example
A
B 0 1
0 1
1
0
1
F = A'B + AB’ + AB
(A'B + AB) + (AB’ + AB)
= A+ B
1
A B F
0 0 0
0 1 1
1 0 1
1 1 1
Another Example
B = 1
F = A + B
A
A = 1
A B F
0 0 1
0 11
10 1
111
Yet Another Example
A
B
F = 1
Groups of more †han †wo 1's can be combined
•
3-Variable Karnaugh Map Showing
Min†erm Locations
A
BC o 1
No†e †he order of
the BCvariables:
0 0
0 1
1 1
1 0
ABC = 010
00
01
11
10
ABC 101

k-mapping with 2 inputs 3 inputs and 4 inputs value

  • 1.
  • 2.
    What are KarnaughMaps? A simpler way †o handle mos† (bu† no† all) jobs of mani ula†in logic functions.
  • 3.
    Karcaugh Advantages • Minimizationcan be done more sys†ema†ically • Much simpler †o find minimum solutions • Easier †o see wha† is happening (graphical) Almost always used instead of boolean minimization.
  • 4.
    2-bi† Gray Code 00 01 11 10 Gray Codes •Gray code is a binary value encoding in which adjacen† values only differ by one bi†
  • 5.
    F = A’ F=B Keyidea: Gray code adjacency allows use of simplification theorems A B 0 0 O 0 Truth Table Adjacencies These are adjacent in a9naycode sense - †hey differ by 1bi† We can apply XY + XY’ = X A'B’ + A'B = A’(B'+B) A’(1) = A Some idea: A'B + AB = B Problem: Physical adjacency in †ruth †abIe does not indicate gray code adjacency
  • 6.
    2-Variable Karnaugh A-0, B—0 A-0,B-1 A=1, B=0 A-1, B-1 A differen† way †o draw a †ru†h †abIe: by folding i†
  • 7.
    A 0 1 0 10 ‹ 0 0 0 Karnaugh • In a K-map, physical adjacency does imply gray code adjacency A B F =A’B’ + A'B = A’ B 0 1 1 F = A'B + AB B
  • 8.
    A B F 00 1 0 1 1 1 0 0 1 1 0 2-Variable Karnaugh
  • 9.
    A B F 00 1 0 1 1 1 0 0 1 1 , 0 2-Variable Karnaugh A B 0 1 0
  • 10.
    A B F 00 1 0 1 1 1 0 0 1 1 , 0 2-Variable Karnaugh A 0 1 1 1
  • 11.
    A B F 00 1 0 1 1 1 0 0 1 1 , 0 - 0 *0 2-Variable Karnaugh A B 0 1
  • 12.
    A B F 00 1 0 1 1 1 0 0 1 1 , 0 2-Variable Karnaugh A B 0 1 1 0 1 0 0 1 F = A'B’ + A'B = A’
  • 13.
    A B F 00 1 0 1 1 1 0 0 1 1 , 0 0 0 2-Variable Karnaugh A B 0 1 A = 0 F = A’
  • 14.
    A B F 00 0 0 1 1 1 0 1 1 1 1 Another Example A B 0 1 0 1 1 0 1 F = A'B + AB’ + AB (A'B + AB) + (AB’ + AB) = A+ B 1
  • 15.
    A B F 00 0 0 1 1 1 0 1 1 1 1 Another Example B = 1 F = A + B A A = 1
  • 16.
    A B F 00 1 0 11 10 1 111 Yet Another Example A B F = 1 Groups of more †han †wo 1's can be combined
  • 17.
    • 3-Variable Karnaugh MapShowing Min†erm Locations A BC o 1 No†e †he order of the BCvariables: 0 0 0 1 1 1 1 0 ABC = 010 00 01 11 10 ABC 101