Partitioning-Based Test Access Mechanism for SoC Diagnosis
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Solution Overview
Problem
Current test access mechanisms for System-on-Chip (SoC) designs with multiple cores face challenges in failure diagnosis, as they cannot distinguish between defects in different cores, leading to poor diagnosis resolution, and require additional resources such as pins and time for effective diagnosis.
Innovation Solution
The implementation of a partitioning-based Test Access Mechanism (TAM) that divides scan cells into non-overlapping partitions using partitioning scheme generators, allowing for the generation of partition pass/fail signals to identify failing cells and improve diagnostic resolution without increasing test data volume or hardware overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a broadcast-based Test Access Mechanism is used to test multiple cores in parallel, then the number of chip level pins remains constant and test time is reduced, but the ability to distinguish between defects in different cores is lost, resulting in poor diagnosis resolution
Solution Approach 1:
The scan chains are divided into multiple non-overlapping partitions, where each partition is associated with a specific core. This segmentation allows the test response to be traced back to the specific core that generated it, thereby resolving the inability to distinguish defects in different cores while maintaining parallel testing efficiency
Solution Approach 2:
Partition pass/fail signals are introduced as intermediary elements between the scan chains and the observation pins. These signals act as mediators that carry diagnostic information from the partitioned scan chains to the output, enabling core-level defect identification without requiring separate observation pins for each core
2Measurement precision
If partitioning scheme generators and additional logic are added to enable failure diagnosis, then diagnostic resolution is improved, but hardware overhead and device complexity increase
Solution Approach 1:
The partitioning scheme generators are integrated into the existing scan chain infrastructure, merging the diagnostic functionality with the existing test architecture. This combining approach enables core-level diagnosis without requiring completely separate hardware systems, thereby limiting the increase in device complexity
Solution Approach 2:
The partitioning scheme generators serve multiple functions: they partition the scan chains for diagnostic purposes, generate pass/fail signals for each partition, and enable both parallel testing and core-level diagnosis using the same hardware infrastructure. This multi-functionality reduces the need for additional dedicated hardware components
3Measurement precision
If multiple observation pins are added to increase diagnostic resolution, then the ability to identify failing cells is improved, but the number of pins required increases, affecting ease of manufacture
Solution Approach 1:
Instead of increasing the number of observation pins in the spatial dimension, the solution introduces a temporal dimension by using partition pass/fail signals that are generated at different times for different partitions. This allows diagnostic information from multiple partitions to be observed through a limited number of pins by sequential observation, thereby maintaining ease of manufacture while improving diagnosis resolution
Data Source
AI summary
Disclosed are representative embodiments of methods, apparatus, and systems for partitioning-based Test Access Mechanisms (TAM). Test response data are captured by scan cells of a plurality scan chains in a circuit under test and are compared with test response data expected for a good CUT to generate check values. Based on the check values, partition pass/fail signals are generated by partitioning scheme generators. Each of the partitioning scheme generators is configured to generate one of the partition pass/fail signals for one of partitioning schemes. A partitioning scheme divides the scan cells into a set of non-overlapping partitions. Based on the partition pass/fail signals, a failure diagnosis process may be performed.