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Test data compression is an enabling technology for low-cost test. Compression schemes however, require communication between the system under test and the automated test equipment. This communication, referred to in this paper as synchronization overhead, may hinder the effective deployment of this new test technology for core-based systems-on-a-chip. This paper analyzes the sources of synchronization overhead and discusses the different trade-offs, such as area overhead, test time and automatic test equipment extensions. A novel scalable and programmable on-chip distribution architecture is proposed, which addresses the synchronization overhead problem and facilitates the use of low cost testers for manufacturing test. The design of the proposed architecture is introduced in a generic framework, and the implementation issues (including the test controller and test set preparation) have been considered for a particular case.

Test data compression (TDC) is a promising low-cost methodology for System-on-a-Chip (SOC) test. This is due to the fact that it can reduce not only the volume of test data but also the bandwidth requirements. In this paper we provide a quantitative analysis of two distinctive TDC methods from the system integrator’s standpoint considering a core based SOC environment. The proposed analysis addresses four parameters: compression ratio, test application time, area overhead and power dissipation. Based on our analysis, some future research directions are given which can lead to an easier integration of TDC in the SOC design flow and to further improve the four parameters.

This paper discusses an integrated solution for reducing the volume of test data for deterministic system-on-a-chip testing. The proposed solution is based on a new test data decompression architecture which exploits the features of a core wrapper design algorithm targeting the elimination of useless test data. The compressed test data can be transferred from the automatic test equipment to the on-chip decompression architecture using only one test pin, thus providing an efficient reduced pin count test methodology for multiple scan chains-based embedded cores. In addition to reducing the volume of test data, the proposed solution decreases the control overhead, test application time and power dissipation during scan. Further, it also requires lower on-chip area when compared to the testing scenarios which employ decompression architectures for every scan chain and it eliminates the synchronization overhead between the automatic test equipment and the system-on-a-chip. Moreover, the proposed solution is scalable and programmable and, since it can be considered as an add-on to a test access mechanism of a given width, it provides seamless integration with any design flow. Thus, the proposed integrated solution is an efficient low-cost test methodology for systems-on-a-chip.

Synchronization overhead between the core under test and the automatic test equipment is the main drawback of test data compression/decompression environments, which hinders the deployment of this new embedded test technology. This paper introduces two new methods to reduce the synchronization overhead. Firstly, the synchronization overhead is reduced by tailoring the compressed test set and not the compression method as proposed by previous approaches. It is shown, by means of experimental data, that the proposed method obtains similar or smaller test sets, without modifying the on-chip decoder, thus facilitating the reuse of the existing hardware infrastructure. Secondly, to provide a full scenario for testing complex systems-on-a-chip with multiple embedded cores, a new distribution architecture is introduced. The architecture exploits the features of parallel on-chip decoders and, in contrast to the interleaving architecture recently proposed, no changes to the on-chip decoders are required. In addition to reusing the existing decoders the distinctive features of the proposed architecture are scalability and programmability, which ease the integration into any existing design and test flow.