D-Algorithm
By
Dr. Amin Danial Asham
References
An Introduction to Logic
Circuit Testing
II. D-intersection of different D-cubes that coexist for
different gates in a logic circuit.
• Rules: if one cube assigns a specific signal value,
the other cubes must assign either the same value
or 𝑥, since it not possible to find 1 at one end of a
wore and 0 on the other end.
Therefore,
II. D-intersection of different D-cubes that coexist for
different gates in a logic circuit. (continue)
Inconsistency
Greek symbols 𝝁
and 𝝀 indicate
incompatibilities if both are present in 𝑫cubes with multiple input 𝑫 and 𝑫.
Example:
𝐷𝑥𝐷 ∩ 𝐷0𝐷 = 𝐷𝑥𝐷 ∩ 𝐷0𝐷 = 𝐷0𝐷
Consistency
Inconsistency
𝐷𝑥𝐷 ∩ 𝐷0𝐷
D-Algorithm Steps
1. Select a PDCF for the given fault.
2. Select propagation D-cubes to propagate fault-effect to
primary outputs (D-Drive or Forward-Tracing).
3. Select singular cover cubes to justify internal circuit signals
(Consistency Procedure or Backward-Tracing).
•The D-algorithm’s main problem is that it selects cubes
and singular covers arbitrarily during test generation.
PDC’s
Example 1:
PDCF for the faulty gate is 11D
A
B
D
1
1
D
C
Singular Covers
d
e
F
A
B
D
1
1
1
D
D
0
x
0
D
D
x
0
0
e
1
1
1
0
1
D
0
x
1
D
D
X
0
1
B
1
1
D
X
1
0
D
0
1
x
0
D
D
0
0
1
C
d
e
D
D
1
1
1
1
Test Pattern
F
0
D-Drive
1
d
D
A
Consistency
Procedure
C
0
0
D
0
F
Example 2:
s-a-1
1
1
B
a
4
5
1
0
f
A
B
1
1
B
F
D
x
0
1
D
1
0
x
1
D
D
1
1
0
B
1
a
F
4
G2
G2
1
D
5
D
D
x
NAND
Singular Covers
A
A
1
Inconsistency
A
NAND
PDC’s
PDCF for the faulty gate
is 11𝑫
G3
1
1
D
D
D
D
D
Test
1
1
f
Thanks