04-05-2012, 12:15 PM
On Clustering of Undetectable Single Stuck-At Faults And Test Quality in Full-Scan Circuits
ABSTRACT
We demonstrate that undetectable single stuck-at faults in full-scan benchmark circuits tend to cluster in certain areas. This implies that certain areas may remain uncovered by a test set for single stuck-at faults. We describe an extension to the set of target faults aimed at providing a better coverage of the circuit in the presence of undetectable single stuck-at faults. The extended set of target faults consists of double stuck-at faults that include an undetectable fault as one of their components. The other component is a detectable fault adjacent to the undetectable fault. We present experimental results of fault simulation and test generation for the extended set of target faults.
EXISTING SYSTEM
Fault models used as targets for test generation are expected to guide the generation of tests that will be effective in detecting defects. Thus, a test set generated for single stuck-at faults in a full-scan circuit is expected to detect defects associated with the sites of stuck-at faults. Test sets that contain several different tests for each fault (n-detection test sets) are expected to increase the likelihood of detecting defects associated with the sites of target faults. When a single stuck-at fault is undetectable, it leaves an uncovered site in the circuit. In benchmark circuits, undetectable single stuck-at faults tend to cluster in certain areas. This implies that certain areas of the circuit remain uncovered, or less covered than other areas, by a test set for single stuck-at faults. This phenomenon is discerned from the gate level description of the circuit, and it is independent of layout parameters.
DISADVANTAGES OF EXISTING SYSTEMS
• It cannot detect all stuck at faults
• It cannot detect double stuck at faults
PROPOSED SYSTEM
We demonstrate that undetectable single stuck-at faults tend to cluster in certain areas of benchmark circuits. We define the extended set of target faults that includes double stuck-at faults based on undetectable single stuck-at faults. We also describe a fault simulation and test generation experiment targeting the extended set of faults. We present experimental results of fault simulation and test generation. We discuss the case where complete information about detectable and undetectable faults is not available, and present additional experimental results.
• Clustering Of Undetectable Faults
In this section, we demonstrate that undetectable single stuck-at faults in full-scan benchmark circuits tend to cluster in certain areas of the circuit. We consider the set F1 of un collapsed single stuck-at faults. This allows us to define clustering, based on structural adjacencies between faults in the circuit, without the need to account for undetectable faults that are missing due to fault collapsing.
• Extended Set of Target Faults
In this section, we define an extended set of target stuck-at faults that consists of double stuck-at faults. The goal of the extension is to provide a target for improving the coverage for sites of undetectable single stuck-at faults. We describe a particular way of selecting the double faults. Other approaches can be used instead to define a larger or smaller subset of double faults.
ADVANTAGES OF PROPOSED SYSTEM
• Error checking rate is high.
• Detects double stuck at fault.
ABSTRACT
We demonstrate that undetectable single stuck-at faults in full-scan benchmark circuits tend to cluster in certain areas. This implies that certain areas may remain uncovered by a test set for single stuck-at faults. We describe an extension to the set of target faults aimed at providing a better coverage of the circuit in the presence of undetectable single stuck-at faults. The extended set of target faults consists of double stuck-at faults that include an undetectable fault as one of their components. The other component is a detectable fault adjacent to the undetectable fault. We present experimental results of fault simulation and test generation for the extended set of target faults.
EXISTING SYSTEM
Fault models used as targets for test generation are expected to guide the generation of tests that will be effective in detecting defects. Thus, a test set generated for single stuck-at faults in a full-scan circuit is expected to detect defects associated with the sites of stuck-at faults. Test sets that contain several different tests for each fault (n-detection test sets) are expected to increase the likelihood of detecting defects associated with the sites of target faults. When a single stuck-at fault is undetectable, it leaves an uncovered site in the circuit. In benchmark circuits, undetectable single stuck-at faults tend to cluster in certain areas. This implies that certain areas of the circuit remain uncovered, or less covered than other areas, by a test set for single stuck-at faults. This phenomenon is discerned from the gate level description of the circuit, and it is independent of layout parameters.
DISADVANTAGES OF EXISTING SYSTEMS
• It cannot detect all stuck at faults
• It cannot detect double stuck at faults
PROPOSED SYSTEM
We demonstrate that undetectable single stuck-at faults tend to cluster in certain areas of benchmark circuits. We define the extended set of target faults that includes double stuck-at faults based on undetectable single stuck-at faults. We also describe a fault simulation and test generation experiment targeting the extended set of faults. We present experimental results of fault simulation and test generation. We discuss the case where complete information about detectable and undetectable faults is not available, and present additional experimental results.
• Clustering Of Undetectable Faults
In this section, we demonstrate that undetectable single stuck-at faults in full-scan benchmark circuits tend to cluster in certain areas of the circuit. We consider the set F1 of un collapsed single stuck-at faults. This allows us to define clustering, based on structural adjacencies between faults in the circuit, without the need to account for undetectable faults that are missing due to fault collapsing.
• Extended Set of Target Faults
In this section, we define an extended set of target stuck-at faults that consists of double stuck-at faults. The goal of the extension is to provide a target for improving the coverage for sites of undetectable single stuck-at faults. We describe a particular way of selecting the double faults. Other approaches can be used instead to define a larger or smaller subset of double faults.
ADVANTAGES OF PROPOSED SYSTEM
• Error checking rate is high.
• Detects double stuck at fault.