LBIST Controller Frequency Adaptation for Voltage Drop Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuit testing using Logic Built-in Self-Test (LBIST) is time-consuming and power-intensive, often resulting in unreasonably high electrical power consumption and voltage drops that can lead to failures, especially during start-up.
Innovation Solution
An integrated circuit with a voltage monitoring circuit and a controller that runs LBIST tests in stages, adjusting frequencies based on voltage comparisons to manage current consumption and reduce test time, including a first test at a high frequency, a second test on failing partitions, and subsequent tests at lower frequencies if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LBIST testing is performed at high frequency to reduce test time, then productivity is improved, but power consumption increases unreasonably high
Solution Approach 1:
The patent implements dynamic frequency adjustment where the LBIST test frequency is not fixed but adapts based on real-time voltage monitoring. The system transitions from a static high-frequency approach to a dynamic multi-frequency approach, switching between frequencies based on power conditions to resolve the contradiction between test speed and power consumption
Solution Approach 2:
The system changes the operating parameter (frequency) of the LBIST test based on monitored conditions. By adjusting the frequency parameter dynamically rather than maintaining a constant high frequency, the system achieves both fast testing when power is available and safe operation when power is constrained
2Loss of time
If LBIST testing is performed at high frequency to reduce test time, then test duration is reduced, but voltage drop increases leading to failures
Solution Approach 1:
The patent introduces a feedback mechanism where voltage monitoring continuously observes power conditions during LBIST testing. This feedback loop allows the system to detect voltage drops and respond by adjusting test frequency, thereby maintaining both speed and reliability through condition-based adaptation
Solution Approach 2:
The testing system dynamically adapts its operation based on real-time conditions. Rather than running at fixed high frequency regardless of power state, the system modulates frequency in response to voltage monitoring, ensuring reliability is maintained while minimizing test duration
3Manufacturing precision
If full-chip LBIST scan is performed to test all partitions, then manufacturing precision is improved, but power consumption becomes unreasonably high
Solution Approach 1:
The patent divides the integrated circuit into multiple partitions that can be tested independently. This segmentation allows selective testing of specific partitions based on power conditions rather than forcing full-chip testing, thereby maintaining defect detection capability while reducing power consumption when necessary
Solution Approach 2:
The system performs partial testing by selecting specific partitions for LBIST based on monitored conditions. Rather than always executing full-chip testing, the system applies testing selectively to relevant partitions, achieving adequate manufacturing precision while avoiding excessive power consumption
Data Source
AI summary
A controller executes a first LBIST test on a device at a first shift frequency on a plurality of partitions and detects any voltage drop at sense points in each partition during the test. If a voltage drop is detected, then the test is re-run for those partitions that failed the first test. If failures are detected during the re-execution, then a further test at a lower shift frequency is performed. The partitions can be tested sequentially or in parallel and invention has the advantage of reducing the time taken for executing LBIST when the device is booted.