Rohit Kapur

Towards a standard for embedded core test: an example

Integrated circuits are increasingly designed by embedding pre-designed reusable cores. IEEE P1500 Standard for Embedded Core Test (SECT) is a standard-under-development that aims at improving ease of reuse and facilitating interoperability with respect to the test of such core-based ICs, especially if they contain cores from different sources. This paper briefly describes IEEE P1500, and illustrates through a simplified example its dual compliance concept, its Scalable Hardware Architecture, and its Core Test Language. This paper provides a preliminary, unapproved view on IEEE P1500. The standard is still under development, and this paper only reflects the view of five active participants of the Standardization Committee on its current status.

Iddq test: sensitivity analysis of scaling

While technology is changing the face of the world, it itself is changing by leaps and bounds; there is a continuing trend to put more functionality on the same piece of silicon. Without major changes in the CMOS technology, it has been shown that the scaling of devices has significant impact on the effectiveness of Iddq testing. The sensitivity of Iddq testing to individual device parameters is studied. It is explained how Iddq testing becomes increasingly ineffective in the scaled product with respect to most parameters and can be improved with others.

On IEEE P1500's Standard for Embedded Core Test

The increased usage of embedded pre-designed reusable cores necessitates a core-based test strategy, in which cores are tested as separate entities. IEEE P1500 Standard for Embedded Core Test (SECT) is a standard-under-development that aims at improving ease of reuse and facilitating interoperability with respect to the test of core-based system chips, especially if they contain cores from different sources. This paper briefly describes IEEE P1500, and illustrates through a simplified example its scalable wrapper architecture, its test information transfer model described in a standardized Core Test Language, and its two compliance levels. The standard is still under development, and this paper only reflects the view of six active participants of the standardization committee on its current status.

Speed binning with path delay test in 150-nm technology

What would it take to reduce speed binnings dependency on functional testing? One answer is a structural at-speed test approach that can achieve the same effectiveness as functional testing. The authors of this article offer a formula to relate structural critical-path testing frequency to system operation frequency. They demonstrate that there can be a high correlation between frequencies resulting from structural testing and those resulting from functional testing.

A reconfigurable shared scan-in architecture

In this paper, an efficient technique for test data volume reduction based on the shared scan-in (Illinois Scan) architecture and the scan chain reconfiguration (Dynamic Scan) architecture is defined. The composite architecture is created with analysis that relies on the compatibility relation of scan chains. Topological analysis and compatibility analysis are used to maximize gains in test data volume and test application time. The goal of the proposed synthesis procedure is to test all detectable faults in broadcast test mode using minimum scan-chain configurations. As a result, more aggressive sharing of scan inputs can be applied for test data volume and test application time reduction. The experimental results demonstrate the efficiency of the proposed architecture for real-industrial circuits.

On using IEEE P1500 SECT for test plug-n-play

System chips are increasingly designed by embedding reusable cores. A core-based test strategy for such ICs is often attractive and sometimes even mandatory. IEEE P1500 SECT is a standard under development that standardizes a core test language and a core wrapper, in order to facilitate plug-n-play core testing. In this paper, we describe how one standard supports both easy integration and interoperability as well as flexibility and scalability. Possible usage scenarios of the standard for core providers, core users, and EDA tool developers are sketched.

Changing the scan enable during shift

This paper extends the reconfigurable shared scan-in architecture (RSSA) to provide additional ability to change values on the scan configuration signals (scan enable signals) during the scan operation on a per-shift basis. We show that the extra flexibility of reconfiguring the scan chains every shift cycle reduces the number of different configurations required by RSSA while keeping test coverage the same. In addition a simpler analysis can be used to construct the scan chains. This is the first paper of its kind that treats the scan enable signal as a test data signal during the scan operation of a test pattern. Results are presented on some ISCAS as well as industrial circuits.

Overview of the IEEE P1500 standard

Design reuse has been a key enabler to efficient ,SystemOn-Chip creation, by allowing pre-designed functions to be leveraged, thereby reducing development cycles and time to market, The test of these pre-designed blocks, often referred to as cores, is a primordial factor to successful design reuse methodologies, and must be considered by anticipation with various degrees of challenges depending on the mergeable or non-mergeable nature of the core. This paper presents the state and accomplishments of the IEEE 1500 proposal for the test of non-mergeable cores.

Minimizing the Impact of Scan Compression

Scan is widely accepted as the basis for reducing test cost and improving quality, however its effectiveness is compromised by increasingly complex designs and fault models that can result in high scan data volume and application time. The authors present a scan compression method designed for minimal impact in all aspects: area overhead, timing, and design flow. Easily adopted on top of existing scan designs, the method is fully integrated in the scan synthesis and test generation flows. Data and test time compressions of over 10times were obtained on industrial designs with negligible overhead and no impact on schedule.

Efficient compression of deterministic patterns into multiple PRPG seeds

Recent test-cost reduction methods are based on controlling the initial state (seed) of a pseudo-random pattern generator (PRPG) so that deterministic values are loaded in selected scan cells. Combined with an unload-data compression technique, PRPG seeding reduces test data volume and application time. This paper presents a method of mapping each scan load to multiple PRPG seeds, computed so that test pattern count, data volume, and, therefore, test cost are minimized. This method also allows smaller and fewer PRPGs, reducing the area overhead of test-compression circuitry. The results on deep-submicron industrial designs, show significant test cost reduction when this method is applied with either X-tolerant or X-free unload-data compression