Nicola Nicolici

Bio: Nicola Nicolici is an academic researcher from McMaster University. The author has contributed to research in topics: Design for testing & Automatic test pattern generation. The author has an hindex of 32, co-authored 134 publications receiving 3528 citations. Previous affiliations of Nicola Nicolici include University of Southampton.

Scan architecture with mutually exclusive scan segment activation for shift- and capture-power reduction

Abstract: Power dissipation during scan testing is becoming an important concern as design sizes and gate densities increase. While several approaches have been recently proposed for reducing power dissipation during the shift cycle (minimum-transition don't care fill, special scan cells, and scan chain partitioning), limited work has been carried out toward reducing the peak power during test response capture and the few existing approaches for reducing capture power rely on complex automatic test pattern generation (ATPG) algorithms. This paper proposes a scan architecture with mutually exclusive scan segment activation which overcomes the shortcomings of previous approaches. The proposed architecture achieves both shift and capture-power reduction with no impact on the performance of the design, and with minimal impact on area and testing time (typically 2%-3%). An algorithmic procedure for assigning flip-flops to scan segments enables reuse of test patterns generated by standard ATPG tools. An implementation of the proposed method had been integrated into an automated design flow using commercial synthesis and simulation tools which was used on a wide range of benchmark designs. Reductions up to 57% in average power, and up to 44% and 34% in peak-power dissipation during shift and capture cycles, respectively, were obtained when using two scan segments. Increasing the number of scan segments to six leads to reductions of 96% and 80% in average power and, respectively, maximum number of simultaneous transitions.

Algorithms for State Restoration and Trace-Signal Selection for Data Acquisition in Silicon Debug

Abstract: To locate and correct design errors that escape pre-silicon verification, silicon debug has become a necessary step in the implementation flow of digital integrated circuits. Embedded logic analysis, which employs on-chip storage units to acquire data in real time from the internal signals of the circuit-under-debug, has emerged as a powerful technique for improving observability during in-system debug. However, as the amount of data that can be acquired is limited by the on-chip storage capacity, the decision on which signals to sample is essential when it is not known a priori where the bugs will occur. In this paper, we present accelerated algorithms for restoring circuit state elements from the traces collected during a debug session, by exploiting bitwise parallelism. We also introduce new metrics that guide the automated selection of trace signals, which can enhance the real-time observability during in-system debug.

Variable-length input Huffman coding for system-on-a-chip test

Abstract: This paper presents a new compression method for embedded core-based system-on-a-chip test. In addition to the new compression method, this paper analyzes the three test data compression environment (TDCE) parameters: compression ratio, area overhead, and test application time, and explains the impact of the factors which influence these three parameters. The proposed method is based on a new variable-length input Huffman coding scheme, which proves to be the key element that determines all the factors that influence the TDCE parameters. Extensive experimental comparisons show that, when compared with three previous approaches, which reduce some test data compression environment's parameters at the expense of the others, the proposed method is capable of improving on all the three TDCE parameters simultaneously.

Power-Aware Testing and Test Strategies for Low Power Devices

Abstract: Managing the power consumption of circuits and systems is now considered one of the most important challenges for the semiconductor industry Elaborate power management strategies, such as dynamic voltage scaling, clock gating or power gating techniques, are used today to control the power dissipation during functional operation The usage of these strategies has various implications on manufacturing test, and power-aware test is therefore increasingly becoming a major consideration during design-for-test and test preparation for low power devices This book explores existing solutions for power-aware test and design-for-test of conventional circuits and systems, and surveys test strategies and EDA solutions for testing low power devices

Post-silicon validation opportunities, challenges and recent advances

Abstract: Post-silicon validation is used to detect and fix bugs in integrated circuits and systems after manufacture. Due to sheer design complexity, it is nearly impossible to detect and fix all bugs before manufacture. Post-silicon validation is a major challenge for future systems. Today, it is largely viewed as an art with very few systematic solutions. As a result, post-silicon validation is an emerging research topic with several exciting opportunities for major innovations in electronic design automation. In this paper, we provide an overview of the post-silicon validation problem and how it differs from traditional pre-silicon verification and manufacturing testing. We also discuss major post-silicon validation challenges and recent advances.

Embedded deterministic test

Abstract: This paper presents a novel test-data volume-compression methodology called the embedded deterministic test (EDT), which reduces manufacturing test cost by providing one to two orders of magnitude reduction in scan test data volume and scan test time. The presented scheme is widely applicable and easy to deploy because it is based on the standard scan/ATPG methodology and adopts a very simple flow. It is nonintrusive as it does not require any modifications to the core logic such as the insertion of test points or logic bounding unknown states. The EDT scheme consists of logic embedded on a chip and a new deterministic test-pattern generation technique. The main contributions of the paper are test-stimuli compression schemes that allow us to deliver test data to the on-chip continuous-flow decompressor. In particular, it can be done by repeating certain patterns at the rates, which are adjusted to the requirements of the test cubes. Experimental results show that for industrial circuits with test cubes with very low fill rates, ranging from 3% to 0.2%, these schemes result in compression ratios of 30 to 500 times. A comprehensive analysis of the encoding efficiency of the proposed compression schemes is also provided.

Survey of Test Vector Compression Techniques

Abstract: Test data compression consists of test vector compression on the input side and response, compaction on the output side This vector compression has been an active area of research This article summarizes and categories these techniques The focus is on hardware-based test vector compression techniques for scan architectures Test vector compression schemes fall broadly into three categories: code-based schemes use data compression codes to encode test cubes; linear-decompression-based schemes decompress the data using only linear operations (that is LFSRs and XOR networks) and broadcast-scan-based schemes rely on broadcasting the same values to multiple scan chains

System comprising a semiconductor device and structure

Abstract: A system includes a semiconductor device. The semiconductor device includes a first single crystal silicon layer comprising first transistors, first alignment marks, and at least one metal layer overlying the first single crystal silicon layer, wherein the at least one metal layer comprises copper or aluminum more than other materials; and a second single crystal silicon layer overlying the at least one metal layer. The second single crystal silicon layer comprises a plurality of second transistors arranged in substantially parallel bands. Each of a plurality of the bands comprises a portion of the second transistors along an axis in a repeating pattern.