1. An Efficient Test Vector Compression Scheme
Using Selective Huffman Coding
Under the guidance of Prof.Aarthi
Presented By
Dipu P
12MVD0060
Venketa Ramesh E 12MVD0062
HarshaVardhan B 12MVD0063

2. INTRODUCTION:
A SOC based design provide several design challenges
These chips are composed of several reusable intellectual
property (IP) cores
The volume of test data for a SOC is growing rapidly as IP
cores become more complex
Extreme challenges to current tools and methodologies

3. 1/2
 In present days the complexity of SOC is keep on
increasing, so for testing those IC’s requires huge cost
 Various factors of ATE are limitations to a testing technique
and methodology
 Various techniques available for reducing the test data
 They are BIST and Test Data Compression

4. 1/3
•
Various methods
i) code based schemes
ii) Linear-decompression based schemes
iii) Broad cast based schemes
• Code Based Schemes
1) Fixed to Fixed
2) Fixed to Variable
3) Variable to fixed
4) Variable to Variable

5. Huffman Encoding Scheme
1/4
Building up of Huffman Tree
Selective Huffman
 Compression Ratio
1
0010
0010
0010
0001
1100
2
0100
0100
0110
0100
1000
3
4
5
6
0010
0010
0010
0010
0100
0110
0110
0010
0111
0111
0000
0000
0010
0010
0010
0010
0110
0100
0010
0010
7
1011
0010
0100
0111
0111
Test File under consideration
8
9
10
11
12
0100
0100
0110
0111
0111
0010
0110
0010
0100
0010
0100
0010
0010
0100
0100
0110
0010
1000
1000
1111
0010
0000
0101
0101
0011

6. ENCODING SCHEME
2/4
0010010000100110000000101
0110100001001000110011010
1011010101011000001110000
1111000001101010101010000
SORTED
TEST VECTORS
HUFFMAN TREE
0010
Algorithm of Huffman Encoder
Feed the Test File
Divide in to set of four bits
Sorting the 4-bit block descending order of their
occurrence(frequency)
Tree Development
Encoding

7. 3/4
 Feed the Test File.
 Divide in to set of four bits.
 Sorting the 4-bit block descending order of their
occurrence(frequency).
 Select the most frequently occurring bit sets.
(Those having High Frequency).
 Huffman Coding For the Selected Set.
 Set MSB=1 for the Selected encoded bits.
 Set MSB=0 for unselected bit sets.
 Zero tag indicate no need of decompression .

8. 4/4
Comparison Between Huffman And
Selective Huffman

15. Selective Huffman Decoding-Look Up Table
Method

16. 1/2
RESULTS-Decoded Output and
Comparison
Huffman
Selective
Huffman
Total
Combinational
functions
102
73
Total Registers
41
40
% of Compression=
% of
Compression=19.166
Decoded output for a given serial input

17. 2/2
Total no of bits=240
Compressed bits for Huffman=178
Compressed bits for Huffman=194

18. CONCLUSION




Importance of compression and decompression in testing field.
Huffman Compression-Decompression
Selective Huffman Compression-Decompression
Simple-Decoder with Lesser Logic Elements.
Results indicate that the proposed scheme can provide test
data compression nearly equal to that of an optimum
Huffman code with much less area overhead for the
decoder.

19. REFERENCES
[1] Xrysovalantis Kavousianos, Emmanouil Kalligeros, and Dimitris Nikolos” Optimal Selective
Huffman Coding for Test-Data Compression “IEEE TRANSACTIONS ON COMPUTERS,
VOL. 56, NO. 8, AUGUST 2007
[2] Abhijit Jas, Jayabrata Ghosh-Dastidar, Mom-Eng Ng, and Nur A. ToubaAn “Efficient Test Vector
Compression Scheme Using Selective Huffman Coding” IEEE TRANSACTIONS ON
COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMSJUNE 2003.
[3] J. Aerts and E. J. Marinissen, “Scan chain design for test time reduction
in core-based ICs,” in Proc. Int. Test Conf., 1998, pp. 448–457.
[4] I. Bayraktaroglu and A. Orailoglu, “Test volume and application time reduction through scan
chain
concealment,” in Proc. Design Automation Conf., 2001, pp. 151–155.
[5] M. L. Bushnell and V. D. Agrawal, Essentials of Electronic Testing For Digital, Memory, And
MixedSignal VLSI Circuits. Norwell, MA Kluwer, 2000.
[6] Ji-Han Jiang*, Chin-Chen Chang*, and Tung-Shou Chen” An Efficient Huffman Decoding
Method
Based onPattern Partition and Look-up Table”
[7] Kinjal A. Bhavsar” Analysis of Test Data Compression Techniques Based on Complementary
Huffman Coding” International Journal of Engineering Science and Technology (IJEST)

20. THANK YOU