Test-access mechanism optimization for core-based three-dimensional SOCs

Embedded cores in a core-based system-on-chip (SOC) are not easily accessible via chip I/O pins. Test-access mechanisms (TAMs) and test wrappers (e.g., the IEEE Standard 1500 wrapper) have been proposed for the testing of embedded cores in a core-based SOC in a modular fashion. We show that such a modular testing approach can also be used for emerging three-dimensional integrated circuits based on through-silicon vias (TSVs). Core-based SOCs based on 3D IC technology are being advocated as a means to continue technology scaling and overcome interconnect-related bottlenecks. We present an optimization technique for minimizing the post-bond test time for 3D core-based SOCs under constraints on the number of TSVs, the TAM bitwidth, and thermal limits. The proposed optimization method is based on a combination of integer linear programming, LP-relaxation, and randomized rounding. It considers the Test Bus and TestRail architectures, and incorporates wire-length constraints in test-access optimization. Simulation results are presented for the ITC 02 SOC Test Benchmarks and the test times are compared to that obtained when methods developed earlier for two-dimensional ICs are applied to 3D ICs. The test time dependence on various 3D parameters (e.g. 3D placement, the number of layers, thermal constraints, and the number of TSVs) is also studied.     

基于复用的SOC测试集成和IEEE P1500标准

以复用核测试为目标的测试策略是解决SOC测试问题的基础.IEEE P1500标准是国际上正在制订的嵌入式核测试标准,该标准旨在简化核测试信息的复用,提高SOC级测试集成的效率.文章介绍了截至目前为止P1500标准的制订情况,包括嵌入式核测试的体系结构、P1500的标准化目标,以及P1500的两级服从认证等.     

Modular and rapid testing of SOCs with unwrapped logic blocks

Extensive research has been carried out for test planning of core-based system-on-a-chip devices. Most of the prior work assumes that all of the embedded cores are wrapped for test purpose. However, some designs may contain user-defined logic or cores that cannot be wrapped due to area constraints or timing violations. This paper discusses how these unwrapped logic blocks can be tested rapidly by adapting the TestRail architecture, which uses only the test control mechanism and the test instructions available through the IEEE 1500 standard for embedded core test. A new test scheduling algorithm, which facilitates a concurrent test of both unwrapped logic blocks and IEEE 1500-wrapped cores, is proposed, and experiments show that it outperforms a previous approach when the available number of tester channels and/or the number of unwrapped logic blocks are small.     

IEEE Standard 1500 Compatible Delay Test Framework

Rapid advances in semi-conductor technology have made timing-related defects increasingly crucial in core-based system-on-chip designs. Currently, modular test strategies based on IEEE Standard 1500 are applied to test the functionality of each embedded core in system-on-chip (SoC) designs but fail to verify the corresponding timing specifications. In this paper, to achieve high quality of delay tests, hardware implementation of an embedded Delay Test Framework including the modified test wrappers and the Embedded delay test mechanism is presented to build an entirely embedded delay test environment where at-speed clock is applied inside the chip to increase test accuracy. Additionally, the proposed delay test framework is capable of supporting all current solutions of core-based delay test. The experimental results successfully demonstrate the delay testing application using the proposed framework to a Crypto Processor with satisfying test quality and effectiveness.      

一种基于嵌入式IP内核模块的测试方法

嵌入式内核结构的测试正面临着新的挑战,需要提出有效的测试方法。针对IP内核模块测试所面临的技术难点,详细介绍了IP核模块实现测试所需要构建的硬件环境和完整的测试方法,并分析了由测试理论和方法而形成的国际公认标准IEEEP1500。     

基于安全控制边界单元的IP核测试封装方法

为了解决测试信息传递的问题,IEEE组织推出了IEEE1500 IP(Intellectual Property)核测试封装标准以标准化口核测试接口.然而该标准给出的典型测试封装存在由测试数据扫描移人造成的不安全隐患.本文提出了一种基于安全控制边界单元的IP核测试封装方法.这种方法的核心思想是在典型的测试封装边界单元的...     

CAS-BUS: A Test Access Mechanism and a Toolbox Environment for Core-Based System Chip Testing

As System on a Chip (SoC) testing faces new challenges, some new test architectures must be developed. This paper describes a Test Access Mechanism (TAM) named CAS-BUS that solves some of the new problems the test industry has to deal with. This TAM is scalable, flexible and dynamically reconfigurable. The CAS-BUS architecture is compatible with the IEEE P1500 standard proposal in its current state of development, and is controlled by Boundary Scan features.This basic CAS-BUS architecture has been extended with two independent variants. The first extension has been designed in order to manage SoC made up with both wrapped cores and non wrapped cores with Boundray Scan features. The second deals with a test pin expansion method in order to solve the I/O bandwidth problem. The proposed solution is based on a new compression/decompression mechanism which provides significant results in case of non correlated test patterns processing. This solution avoids TAM performance degradation.These test architectures are based on the CAS-BUS TAM and allow trade-offs to optimize both test time and area overhead. A tool-box environment is provided, in order to automatically generate the needed component to build the chosen SoC test architecture.     

Enhanced Reduced Pin-Count Test for Full-Scan Design

This paper presents enhanced reduced pin-count test (E-RPCT) for low-cost test. E-RPCT is an extension of traditional RPCT for circuits in which a large number of digital IC pins is multiplexed for scan. The basic concept of E-RPCT is to provide access to the internal scan chains via an IEEE 1149.1 compatible boundary-scan architecture, instead of direct access via the IC pins. The boundary-scan chain performs serial/parallel conversion of test data. E-RPCT also provides I/O wrap to test non-contacted pins. The paper presents E-RPCT for full-scan design, as well as for full-scan core-based design.     

A Gated Clock Scheme for Low Power Testing of Logic Cores

Test power is now a big concern in large core-based systems. In this paper, we present a general approach for minimizing power consumption during test of integrated circuits or embedded cores. The proposed low power/energy technique is based on a gated clock scheme that can be used in a test-per-scan or a test-per-clock environment. The idea is to reduce the clock rate on the scan path (test-per-scan) or the test pattern generator (test-per-clock) without increasing the test time. Numerous advantages can be found in applying such a technique.     

基于外壳架构与测试访问机制的数字芯核可测试性设计

深亚徽米技术的应用以及芯核的嵌入性特点.使传统的测试方法不再能满足芯核测试的需要.IEEEStdl 500针对此问题提出了芯核的可测试性设计方案——外壳架构和测试访问机制.基于IEEE Stdl 500.以74373与741 38软梭为例,提出数字芯梭可测试性设计的方法,并通过多种指令仿真验证了设计的合理性;设计的TAM控制器复用JTAC-端口,节约了测试端口资源.提供了测试效率.     

Design of reconfigurable access wrappers for embedded core based SoC test

Testing of embedded core based system-on-chip (SoC) ICs is a well known problem, and the upcoming IEEE P1500 Standard on Embedded Core Test (SECT) standard proposes DFT solutions to alleviate it. One of the proposals is to provide every core in the SoC with test access wrappers. Previous approaches to the problem of wrapper design have proposed static core wrappers, which are designed for a fixed test access mechanism (TAM) width. We present the first report of a design of reconfigurable core wrappers which allow for a dynamic change in the width of the TAM executing the core test. Analysis of the corresponding scheduling problem indicates that good approximate schedules can be achieved without significant computational effort. Specifically, we derive a O(N/sub C//sup 2/B) time algorithm which can compute near optimal SoC test schedules, where N/sub C/ is the number of cores and B is the number of top level TAMs. Experimental results on benchmark SoCs are presented which improve upon integer programming based methods, not only in the quality of the schedule, but also significantly reduce the computation time.     

Scheduling Tests for 3D Stacked Chips under Power Constraints

This paper addresses Test Application Time (TAT) reduction under power constraints for core-based 3D Stacked ICs (SICs) connected by Through Silicon Vias (TSVs). Unlike non-stacked chips, where the test flow is well defined by applying the same test schedule both at wafer sort and at package test, the test flow for 3D TSV-SICs is yet undefined. In this paper we present a cost model to find the optimal test flow. For the optimal test flow, we propose test scheduling algorithms that take the particulars of 3D TSV-SICs into account. A key challenge in testing 3D TSV-SICs is to reduce the TAT by co-optimizing the wafer sort and the package test while meeting power constraints. We consider a system of chips with cores that are accessed through an on-chip JTAG infrastructure and propose a test scheduling approach to reduce TAT while considering resource conflicts and meeting the power constraints. Depending on the test schedule, the JTAG interconnect lines that are required can be shared to test several cores. This is taken into account in experiments with an implementation of the proposed scheduling approach. The results show significant savings in TAT.     

Interconnect Delay Fault Test on Boards and SoCs with Multiple Clock Domains

This paper introduces an interconnect delay fault test (IDFT) controller on boards and system‐on‐chips (SoCs) with IEEE 1149.1 and IEEE 1500 wrappers. By capturing the transition signals launched during one system clock, interconnect delay faults operated by different system clocks can be simultaneously tested with our technique. The proposed IDFT technique does not require any modification on boundary scan cells. Instead, a small number of logic gates needs to be plugged around the test access port controller. The IDFT controller is compatible with the IEEE 1149.1 and IEEE 1500 standards. The superiority of our approach is verified by implementation of the controller with benchmark SoCs with IEEE 1500 wrapped cores.     

A System-layer Infrastructure for SoC Diagnosis

During IC manufacturing phase, discriminating between good and faulty chips is not enough. In fact, especially in the first phase of the production of a new device, a complete understanding of the possible failures is quickly required to ramp up production yield. For test engineers, dealing with the manufacturing test of Systems-on-chip (SoCs) means to tackle the extraction of diagnostic data from faulty chips. Another equally important aim of diagnosis, in a later step of a product lifecycle, is to find the real root cause of silicon misbehaviors for field returns. At the core test layer, the adoption of diagnosis-oriented Design-for-Testability structures is almost mandatory and many solutions have been worked out for several types of cores; diagnosis data retrieval often consists in the execution of a set of self-test procedures whose application order and/or customization may depend on the obtained results themselves. This paper details the characteristics of a system-layer test architecture able to manage efficiently SoC self-diagnostic procedures. This architecture is composed of a diagnosis-oriented Test Access Mechanism (TAM) and an Infrastructure-IP owning enough intelligence to automatically manage core diagnostic procedures. Both of them have been designed in compliance with the IEEE 1500 Standard for Embedded Core Test and exploit the characteristics of Self-Test structures inserted for the diagnosis of memory, processor and logic cores. This approach to SoC diagnosis minimizes ATE memory requirements for pattern storage and drastically speeds up the complete execution of diagnostic procedures. Experimental results highlight the convenience of the approach with respect to alternative ATE driven diagnosis procedures, while resorting to negligible area overhead.

系统芯片的可测性设计与测试

阐述了系统芯片(SoC)测试相比传统IC测试的困难,SoC可测性设计与测试结构模型,包括测试存取配置、芯核外测试层,以及测试激励源与测试响应汇聚及其配置特性、实现方法与学术研究进展,介绍了基于可复用内嵌芯核的SoC国际测试标准IEEE P1500的相关规约;最后,建议了在SoC可测性设计及测试中需要密切关注的几个理论问题。     

ALTECC_DECODER IP核的IEEE 1500 Wrapper设计

IP核的广泛应用提高了电路集成的效率。由于众多功能各异的IP核集成在电路中,完善的测试机制是确保其正常工作的前提。因此,如何对IP核进行测试成为复用IP核技术必须解决的问题。IEEE Std 1500提供了IP核的测试实现机制,文中基于IEEE 1500研究如何实现IP核的Wrapper设计,实验以Hamming码译码IP核ALTECC_DECODER为测试对象,验证了IEEE 1500 Wrapper可有效地对IP核进行测试。     

Test Planning for Core-based Integrated Circuits under Power Constraints

This paper addresses reduction of test cost for core-based non-stacked integrated circuits (ICs) and stacked integrated circuits (SICs) by test planning, under power constraint. Test planning involves co-optimization of cost associated with test time and test hardware. Test architecture is considered compliant with IEEE 1149.1 standard. A cost model is presented for calculating the cost of any test plan for a given non-stacked IC and a SIC. An algorithm is proposed for minimizing the cost. Experiments are performed with several ITC’02 benchmark circuits to compare the efficiency of the proposed power constrained test planning algorithm against near optimal results obtained with Simulated Annealing. Results validate test cost obtained by the proposed algorithm are very close to those obtained with Simulated Annealing, at significantly lower computation time.     

SoC的存储器Wrapper设计及故障测试

在系统芯片SoC测试中,存储器的可靠性测试是一项非常重要内容.IEEE Std 1500是专门针对嵌入式芯核测试所制定的国际标准,规范了IP核提供者和使用者之间的标准接口.基于此标准完成针对SoC存储器的Wrapper测试壳结构和控制器的设计.以32×8的SRAM为测试对象进行测试验证.结果表明,系统能够准确的诊断出存储器存在故障.     

On Concurrent Test of Core-Based SOC Design

In this paper, a method to solve the resource allocation and test scheduling problems together in order to achieve concurrent test for core-based System-On-Chip (SOC) designs is presented. The primary objective for concurrent SOC test is to reduce test application time under the constraints of SOC pins and peak power consumption. The methodology used in this paper is not limited to any specific Test Access Mechanism (TAM). Additionally, it can also be applied to SOC budgeting at design phase to predict a tradeoff between test application time and SOC pins needed. The contribution of this paper is the formulation of the problem as a well-known 2-dimensional bin-packing problem. A best-fit heuristic algorithm is adopted to achieve optimal solution.