Self-Calibrated Voltage Scaling for Reliable Logic Timing
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Solution Overview
Problem
As integrated circuits with increasing transistor density and operating frequency face challenges in managing power consumption, reducing supply voltage to lower power consumption can lead to incorrect operation, and leakage currents become a significant issue with advanced process nodes, making it difficult to balance power management with performance and thermal requirements.
Innovation Solution
An integrated circuit with a self-calibration unit and local power manager that iteratively tests supply voltage magnitudes to determine the lowest voltage for correct operation, adjusting the supply voltage dynamically based on measured propagation delays through a series of logic gates to optimize power consumption while ensuring performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If supply voltage is reduced to lower power consumption, then power consumption decreases, but incorrect operation occurs at given operating frequency
Solution Approach 1:
The patent implements dynamic voltage and frequency scaling by making the supply voltage and operating frequency adjustable and interdependent. The system dynamically selects operating points from a set of predefined voltage-frequency pairs, allowing the circuit to adapt its power consumption and performance characteristics based on operational requirements rather than using fixed static values.
Solution Approach 2:
The patent changes the operating parameters (supply voltage and frequency) of the logic circuit to optimize power consumption. By providing a set of predefined voltage-frequency pairs and selecting appropriate combinations, the system can reduce voltage to save power while maintaining correct operation at the corresponding reduced frequency, or increase voltage to support higher frequencies when performance is critical.
2Reliability
If supply voltage is increased to maintain correct operation, then correct operation is ensured, but leakage current increases
Solution Approach 1:
The system dynamically adjusts supply voltage to the minimum necessary level for correct operation at the current frequency and process conditions. By continuously monitoring and adapting voltage levels rather than maintaining a fixed high voltage, the system ensures correct operation while minimizing leakage current that would occur at unnecessarily high voltage levels.
Solution Approach 2:
The patent utilizes process calibration data to determine the actual voltage threshold for correct operation and adjusts the supply voltage parameter accordingly. This allows the system to operate at lower voltages that match the actual circuit characteristics, reducing leakage current while maintaining reliable operation.
3Reliability
If static supply voltage is used across all variations, then manufacturing variations are covered, but power consumption cannot be optimized
Solution Approach 1:
The patent performs process calibration during manufacturing to characterize each circuit's actual voltage threshold for correct operation. This preliminary measurement allows the system to store calibration data that reflects the specific circuit's characteristics, enabling later dynamic voltage adjustment that is optimized for that particular circuit rather than using a conservative static voltage that would work for all circuits but waste power on faster-than-average ones.
Solution Approach 2:
The system uses calibration data obtained during manufacturing as feedback to determine the appropriate supply voltage for each circuit. This feedback mechanism allows the voltage to be set based on actual circuit performance characteristics rather than worst-case assumptions, enabling power optimization while ensuring correct operation for each specific circuit instance.
Data Source
AI summary
In one embodiment, an integrated circuit includes a self calibration unit configured to iterate a test on a logic circuit in the integrated circuit at respectively lower supply voltage magnitudes until the test fails. A lowest supply voltage magnitude at which the test passes is used to generate a requested supply voltage magnitude for the integrated circuit. In an embodiment, an integrated circuit includes a series connection of logic gates physically distributed over an area of the integrated circuit, and a measurement unit configured to launch a logical transition into the series and detect a corresponding transition at the output of the series. The amount of time between the launch and the detection is used to request a supply voltage magnitude for the integrated circuit.