Chapter 3 Testability Measure.pdf

An Example of Combinational Circuit (2/3)
An Example of Combinational Circuit (3/3)
First, calculate the TM for the nodes on the
second level, F, H, and G
1.CC1(F)=CC1(A)+CC1(B)+CC1(C)+1=4
2.CC0(F)=min{CC0(A), CC0(B), CC0(C)}+1=2
3.CC1(H)=min{CC0(A), CC0(B)}+1=2
4.CC0(H)=CC1(A)+CC1(B)+1=3
5.CC1(G)=CC0(C)+1=2
6.CC0(G)=CC1(C)+1=2
These TM values are then used in calculating
the primary output controllability
7.CC1(Y)=min{CC1(F), CC1(H)}+1=3
8.CC0(Y)=CC0(F)+CC0(H)+1=6
9.CC1(Z)=min{CC0(H), CC0(G)}+1=3
10.CC0(Z)=CC1(H)+CC1(G)+1=5
A
B
C
G1
G2
G3
H
F
G
G4
G5
Y
Z
The observability of a node indicates the
effort needed to observe the logic value on
the node at a primary output
For second level,
11.CO Y (F)=CO(Y)+CCO(H)+1=5
12.CO Z (G)=CO(Z)+CC1(H)+1=4
13.CO Y (H)=CO(Y)+CC0(F)+1=4
14.CO Z (H)=CO(Z)+CC1(G)+1=5
For primary inputs,
15. CO Z (C)=CO Z (G)+1=[CO(Z)+CC1(H)+1]+1 =5
(line C)
16. CO Y (C)=CO Y (F)+CC1(A)+CC1(B)+1
=[CO(Y)+CC0(H)+1]+CC1(A)+CC1(B)+1=8
(line C)
17.CO YH (A)=CO Y (H)+CC1(B)+1=6
18.CO Z (A)=CO Z (H)+CC1(G)+1=8
A
B
C
CC1(F)=4
CC0(F)=2
CC1(H)=2
CC0(H)=3
CC1(G)=2
CC0(G)=2
CC1(Y)=3
CC0(Y)=6
CC1(Z)=3
CC0(Z)=5
G1
G2
G3
H
F
G
G4
G5
Y
Z
P.L.Lai, VLSI Testing 2010 Chapter 3-13
P.L.Lai, VLSI Testing 2010 Chapter 3-14
SCOAP for Sequential Circuit (1/5)
Sequential controllability and observability calculation
The combinational and sequential
controllability measures of signal d:
CC0(d)=min{CC0(a), CC0(b)}+1
SC0(d)=min{SC0(a), SC0(b)}
CC1(d)=CC1(a)+CC1(b)+1
SC1(d)=SC1(a)+SC1(b)
SCOAP for Sequential Circuit (2/5)
The combinational and sequential controllability and
observability measures of q:
CC0(q)=min{CC0(d)+CC0(CK)+CC1(CK)+CC0(r), CC1(r)+CC0(CK)}
SC0(q)=min{SC0(d)+SC0(CK)+SC1(CK)+SC0(r)+1, SC1(r)+SC0(CK)}
CC1(q)=CC1(d)+CC0(CK)+CC1(CK)+CC0(r)
SC1(q)=SC1(d)+SC0(CK)+SC1(CK)+SC0(r)+1
SCOAP sequential circuit example
P.L.Lai, VLSI Testing 2010 Chapter 3-15
P.L.Lai, VLSI Testing 2010 Chapter 3-16