Flexible PSRO Integrated in Scan Chain for ACV Monitoring
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Solution Overview
Problem
As integrated circuits shrink, across chip variation (ACV) becomes a concern due to differences in transistor behavior, leading to reduced performance and increased power requirements, as current performance screen ring oscillators (PSROs) occupy significant space and require many units to monitor various areas effectively.
Innovation Solution
A flexible performance screen ring oscillator (PSRO) is integrated within a scan chain, utilizing programmable scan chain elements with both forward and backward paths, allowing the PSRO to be of any size and adaptable for monitoring local or global performance areas within integrated circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional performance screen ring oscillators are used to monitor integrated circuit performance, then performance prediction capability is improved, but space occupation and wiring complexity increase significantly
Solution Approach 1:
The patent combines the PSRO functionality with the scan chain structure, merging two separate functions (performance monitoring and scan testing) into a single integrated system. The scan chain elements are configured to form a ring oscillator when needed, eliminating the need for separate PSRO circuits and reducing overall space occupation.
Solution Approach 2:
The scan chain elements are designed to serve multiple functions: they can operate as standard scan chain elements for testing, or be configured to form a performance screen ring oscillator for performance monitoring. This multi-functionality allows the same hardware structure to adapt to different operational modes, reducing the need for dedicated monitoring circuits.
2Adaptability or versatility
If multiple performance screen ring oscillators are deployed to monitor various areas of integrated circuit, then monitoring coverage is improved, but device complexity and wiring increase
Solution Approach 1:
The integrated circuit is divided into multiple scan chain elements, each capable of being configured as part of a PSRO. By segmenting the monitoring function across multiple reusable scan chain elements rather than requiring complete separate PSRO units, the wiring complexity is reduced while maintaining the ability to monitor multiple areas.
Solution Approach 2:
The system dynamically configures scan chain elements to form PSROs of varying sizes and configurations based on monitoring needs. The programmable nature of the scan chain elements allows the PSRO topology to be adjusted without physical reconfiguration, reducing wiring complexity while maintaining adaptability for different monitoring scenarios.
3Reliability
If margins are increased to ensure integrated circuit operates as desired across chip variation, then reliability is improved, but performance and power requirements worsen
Solution Approach 1:
The patent replaces conservative design margins with active performance monitoring and prediction using PSROs integrated in the scan chain. Instead of relying on fixed margins to account for across-chip variation, the system uses real-time oscillation frequency measurements from distributed PSROs to predict actual circuit behavior, enabling tighter margins without sacrificing reliability.
Data Source
AI summary
Aspects of the invention provide for a flexible performance screen ring oscillator (PSRO) integrated within a scan chain. In one embodiment, a circuit structure to create the flexible PSRO includes: a plurality of programmable scan chain elements; and a forward test scan chain path through the plurality of scan chain elements; wherein each of the programmable scan chain elements includes additional circuitry for a backward path, such that the backward path and the forward test scan chain path are combined to create the PSRO.