Self-Calibrated Voltage Scaling for Logic Circuit Power Control

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Solution Overview

Problem

As integrated circuits face increasing power consumption due to higher transistor counts and operating frequencies, managing power consumption while maintaining correct operation is challenging, especially with leakage currents becoming a significant issue at advanced semiconductor fabrication nodes, and reducing supply voltage can lead to incorrect operation.

Innovation Solution

An integrated circuit with a logic circuit, a local power manager, and a self-calibration unit that iteratively tests at lower supply voltage magnitudes until a test fails, determining the lowest supply voltage for correct operation and adjusting the supply voltage dynamically to balance power consumption and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the supply voltage is reduced to manage power consumption, then power consumption decreases, but the operating speed decreases and incorrect operation may occur

Engineering Contradiction:
Improvepower consumptionVSAvoidoperating speed
Core Design Contradiction:
Use of energy by moving objectVSSpeed

Solution Approach 1:

The patent implements dynamic voltage and frequency management by allowing the supply voltage and operating frequency to be adjusted in real-time based on actual operating conditions. The system dynamically selects from multiple voltage/frequency pairs to optimize power consumption while maintaining correct operation, rather than using a static voltage specification.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the supply voltage parameter to multiple discrete levels (e.g., 0.8V, 0.9V, 1.0V, 1.1V) and corresponds each voltage level with a specific operating frequency. This allows the system to select appropriate voltage/frequency pairs based on workload and thermal conditions, optimizing power consumption without causing incorrect operation.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the supply voltage is statically specified to ensure correct operation across all variations, then reliability is maintained, but power consumption cannot be optimized

Engineering Contradiction:
Improvecorrect operationVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system transitions from static voltage specification to dynamic voltage management with multiple operating points. The microcontroller monitors operating conditions and dynamically selects the appropriate voltage/frequency pair, ensuring reliability while optimizing power consumption for each specific operating scenario.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates feedback mechanisms where the microcontroller monitors operating conditions (temperature, workload, battery status) and adjusts the voltage/frequency selection accordingly. This closed-loop approach ensures correct operation is maintained while optimizing power consumption based on actual system state.

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If advanced semiconductor fabrication process nodes are used to increase transistor density, then integration density increases, but leakage current increases

Engineering Contradiction:
Improvetransistor densityVSAvoidleakage current
Core Design Contradiction:
Quantity of substanceVSLoss of energy

Solution Approach 1:

The system uses periodic self-calibration routines to measure actual leakage current and adjust operating parameters accordingly. The microcontroller periodically executes calibration sequences that measure standby current and adjust voltage/frequency settings to minimize leakage-related power consumption while maintaining correct operation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent implements multiple voltage levels that allow the system to operate at lower voltages where leakage current has less impact. By providing discrete voltage options (0.8V, 0.9V, 1.0V, 1.1V), the system can select lower voltage modes when high performance is not required, thereby reducing leakage current effects and overall power consumption.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2405324B1Dynamic voltage and frequency management
Publication Date: 2014.03.05 APPLE INC
  • EP2405324B1 patent drawingFigure 1
  • EP2405324B1 patent drawingFigure 2
  • EP2405324B1 patent drawingFigure 3

AI summary

In one embodiment, an integrated circuit (10) includes a self calibration unit (16) configured to iterate a test on a logic circuit (14) 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.