Integrated Circuit Aging Budget Management
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Solution Overview
Problem
The reliability and expected lifetime of integrated circuits, particularly MOSFETs, are compromised by high electric fields and failure mechanisms such as metal migration, hot carrier injection, time-dependent gate oxide breakdown, and bias temperature instability, which are exacerbated by high operating frequencies and temperatures.
Innovation Solution
An integrated circuit with a clock manager that dynamically adjusts the operating frequency of subsystem units by allocating an aging budget over a moving time window, allowing for boosted frequency operation within the expected lifetime by monitoring and estimating aging rates, thereby limiting accelerated aging and ensuring the circuit operates within reliability limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the operating frequency is increased to improve performance, then productivity is improved, but reliability deteriorates due to accelerated aging from high electric fields
Solution Approach 1:
The patent implements dynamic frequency adjustment by introducing a clock manager that continuously monitors aging indicators and adapts the operating frequency in real-time. The system transitions from a static maximum frequency to a dynamic frequency that fluctuates based on accumulated aging, allowing the circuit to operate at boosted frequencies when aging is low and reduce frequency when aging thresholds are approached, thus resolving the contradiction between maintaining high productivity and ensuring reliability
Solution Approach 2:
The patent establishes a feedback loop where aging indicators (derived from ring oscillator frequency shifts) are continuously measured and fed back to the clock manager. This feedback mechanism enables the system to detect aging accumulation and adjust the operating frequency accordingly, preventing reliability degradation while maximizing productivity during periods of lower aging stress
2Productivity
If the operating frequency is boosted for higher performance, then productivity is improved, but the aging rate increases causing the circuit to reach failure thresholds earlier
Solution Approach 1:
The patent implements periodic action by dividing the operating timeline into discrete time windows and applying an aging budget allocation strategy. Instead of continuous frequency boosting, the system periodically assesses aging status and allows boosted frequency operation only within allocated time budgets, creating a rhythmic pattern of high-performance periods followed by conservative operation periods to extend overall circuit lifetime
Solution Approach 2:
The patent applies preliminary action by pre-allocating an aging budget before the circuit begins operation. This aging budget serves as a predetermined allowance for accelerated aging that can be spent during boosted frequency operation. By establishing this budget in advance and tracking its consumption, the system can safely utilize boosted frequencies to improve productivity while ensuring the total aging accumulation remains within acceptable limits throughout the circuit's operational life
Data Source
AI summary
A circuit block is operated, for limited times, at a boosted frequency that is above the conventional maximum operating frequency specified to achieve an expected lifetime goal. The aging caused by both regular operation and boosted frequency operation is estimated and tracked block-by-block over the both the lifetime of the part and over shorter windows of time (e.g., daily, weekly, monthly, etc.) The shorter time windows are dynamically assigned aging budgets to ensure the part will still be expected to meet the expected lifetime even though its aging will be at an ‘accelerated’ rate whenever the block is operated at a boosted frequency. Aging budgets are assigned based on estimates of the amount of aging the block has experienced, and the amount of aging budget that is left for that time window.