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Low-cost and high-reduction approaches for power droop during launch-on-shift scan-based logic BIST

Low-cost and high-reduction approaches for power droop during launch-on-shift scan-based logic BIST
Low-cost and high-reduction approaches for power droop during launch-on-shift scan-based logic BIST
During at-speed test of high performance sequential ICs using scan-based Logic BIST, the IC activity factor (AF) induced by the applied test vectors is significantly higher than that experienced during its in field operation. Consequently, power droop (PD) may take place during both shift and capture phases, which will slow down the circuit under test (CUT) signal transitions. At capture, this phenomenon is likely to be erroneously recognized as due to delay faults. As a result, a false test fail may be generated, with consequent increase in yield loss. In this paper, we propose two approaches to reduce the PD generated at capture during at-speed test of sequential circuits with scan-based Logic BIST using the Launch-On-Shift scheme. Both approaches increase the correlation between adjacent bits of the scan chains with respect to conventional scan-based LBIST. This way, the AF of the scan chains at capture is reduced. Consequently, the AF of the CUT at capture, thus the PD at capture, is also reduced compared to conventional scan-based LBIST. The former approach, hereinafter referred to as Low-Cost Approach (LCA), enables a 50% reduction in the worst case magnitude of PD during conventional logic BIST. It requires a small cost in terms of area overhead (of approximately 1.5% on average), and it does not increase the number of test vectors over the conventional scan-based LBIST to achieve the same Fault Coverage (FC). Moreover, compared to three recent alternative solutions, LCA features a comparable AF in the scan chains at capture, while requiring lower test time and area overhead. The second approach, hereinafter referred to as High-Reduction Approach (HRA), enables scalable PD reductions at capture of up to 87%, with limited additional costs in terms of area overhead and number of required test vectors for a given target FC, over our LCA approach. Particularly, compared to two of the three recent alternative solutions mentioned above, HRA enables a significantly lower AF in the scan chains during the application of test vectors, while requiring either a comparable area overhead or a significantly lower test time. Compared to the remaining alternative solutions mentioned above, HRA enables a similar AF in the scan chains at capture (approximately 90% lower than conventional scan-based LBIST), while requiring a significantly lower test time (approximately 4.87 times on average lower number of test vectors) and comparable area overhead (of approximately 1.9% on average).
1-12
Omana, Martin
7c091df8-0526-4d15-aa3f-f25dea90dd18
Rossi, Daniele
30c42382-cf0a-447d-8695-fa229b7b8a2f
Beniamino, Edda
191b7785-b817-453b-93c5-92ab2a6c1549
Metra, Cecilia
c420be13-a9cf-471a-96fb-3f43a694ffae
Tirumurti, Chandrasekharan
b8541826-65d5-4973-851b-c5e134701d3a
Galivanche, Rajesh
344d42dd-a120-4720-9c8e-56e4b13007ca
Omana, Martin
7c091df8-0526-4d15-aa3f-f25dea90dd18
Rossi, Daniele
30c42382-cf0a-447d-8695-fa229b7b8a2f
Beniamino, Edda
191b7785-b817-453b-93c5-92ab2a6c1549
Metra, Cecilia
c420be13-a9cf-471a-96fb-3f43a694ffae
Tirumurti, Chandrasekharan
b8541826-65d5-4973-851b-c5e134701d3a
Galivanche, Rajesh
344d42dd-a120-4720-9c8e-56e4b13007ca

Omana, Martin, Rossi, Daniele, Beniamino, Edda, Metra, Cecilia, Tirumurti, Chandrasekharan and Galivanche, Rajesh (2015) Low-cost and high-reduction approaches for power droop during launch-on-shift scan-based logic BIST. IEEE Transactions on Computers, 1-12. (doi:10.1109/TC.2015.2490058).

Record type: Article

Abstract

During at-speed test of high performance sequential ICs using scan-based Logic BIST, the IC activity factor (AF) induced by the applied test vectors is significantly higher than that experienced during its in field operation. Consequently, power droop (PD) may take place during both shift and capture phases, which will slow down the circuit under test (CUT) signal transitions. At capture, this phenomenon is likely to be erroneously recognized as due to delay faults. As a result, a false test fail may be generated, with consequent increase in yield loss. In this paper, we propose two approaches to reduce the PD generated at capture during at-speed test of sequential circuits with scan-based Logic BIST using the Launch-On-Shift scheme. Both approaches increase the correlation between adjacent bits of the scan chains with respect to conventional scan-based LBIST. This way, the AF of the scan chains at capture is reduced. Consequently, the AF of the CUT at capture, thus the PD at capture, is also reduced compared to conventional scan-based LBIST. The former approach, hereinafter referred to as Low-Cost Approach (LCA), enables a 50% reduction in the worst case magnitude of PD during conventional logic BIST. It requires a small cost in terms of area overhead (of approximately 1.5% on average), and it does not increase the number of test vectors over the conventional scan-based LBIST to achieve the same Fault Coverage (FC). Moreover, compared to three recent alternative solutions, LCA features a comparable AF in the scan chains at capture, while requiring lower test time and area overhead. The second approach, hereinafter referred to as High-Reduction Approach (HRA), enables scalable PD reductions at capture of up to 87%, with limited additional costs in terms of area overhead and number of required test vectors for a given target FC, over our LCA approach. Particularly, compared to two of the three recent alternative solutions mentioned above, HRA enables a significantly lower AF in the scan chains during the application of test vectors, while requiring either a comparable area overhead or a significantly lower test time. Compared to the remaining alternative solutions mentioned above, HRA enables a similar AF in the scan chains at capture (approximately 90% lower than conventional scan-based LBIST), while requiring a significantly lower test time (approximately 4.87 times on average lower number of test vectors) and comparable area overhead (of approximately 1.9% on average).

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Accepted/In Press date: 2 October 2015
e-pub ahead of print date: 15 October 2015
Organisations: Electronic & Software Systems

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Local EPrints ID: 393473
URI: http://eprints.soton.ac.uk/id/eprint/393473
PURE UUID: 63a6c3a7-5af8-4ff4-9a2c-58b5079dfac8

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Date deposited: 27 Apr 2016 10:53
Last modified: 15 Mar 2024 00:02

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Contributors

Author: Martin Omana
Author: Daniele Rossi
Author: Edda Beniamino
Author: Cecilia Metra
Author: Chandrasekharan Tirumurti
Author: Rajesh Galivanche

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