Semiconductor Power Gating via Nonvolatile Register Data Retention
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Solution Overview
Problem
Semiconductor devices face challenges in reducing power consumption while maintaining display quality, especially when power supply to certain circuits is stopped, and in efficiently storing data in nonvolatile registers before power is turned off.
Innovation Solution
A semiconductor device incorporating a controller IC with a frame memory, image processing portion, and nonvolatile registers, utilizing OS transistors with metal oxides in the channel formation region to store image data and parameters, and a touch sensor system to predict when power gating can occur, reducing power consumption by temporarily stopping unnecessary circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power supply is stopped to reduce power consumption, then power consumption is reduced, but data may be lost in volatile memory
Solution Approach 1:
The patent applies preliminary action by transferring data from volatile frame memory to nonvolatile register memory before stopping power supply. The controller detects when image data remains unchanged, triggers data transfer to nonvolatile storage in advance, then safely powers down the frame memory without data loss. This resolves the contradiction by preparing the system beforehand to maintain reliability during power reduction.
2Use of energy by moving object
If data is stored in nonvolatile register after sensing no update image data, then power supply can be stopped sooner, but the period for stopping power supply becomes short
Solution Approach 1:
The patent implements feedback by continuously monitoring image data for changes and using this information to control the timing of data transfer and power supply stopping. The controller detects when image data remains unchanged over a predetermined period, uses this feedback to trigger data transfer to nonvolatile register, and then stops power supply. This feedback mechanism optimizes the power reduction period by acting at the precise moment when data stability is confirmed, maximizing energy savings without sacrificing reliability.
3Use of energy by moving object
If power supply is stopped to reduce power consumption, then power consumption is reduced, but display quality may be influenced
Solution Approach 1:
The patent applies preliminary action by completing all necessary data transfers and processing before stopping power supply to circuits that affect display quality. The controller ensures image data is fully transferred to nonvolatile registers and any necessary processing is completed while power is still supplied, then safely powers down peripheral circuits. This timing strategy maintains display quality during active periods while achieving power reduction during idle periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables low power consumption and maintains display quality even when power supply to some circuits is stopped, allowing for efficient data storage and reduced power usage by predicting when to switch to power gating, thereby extending the period of power reduction.
Implementation Method 1
An OS transistor has an extremely low off-state current. With use of this, a technique for reducing refresh frequency in displaying still images and reducing power consumption of a liquid crystal display or an organic EL display has been disclosed
Data Source
AI summary
A semiconductor device with low power consumption is provided. The semiconductor device includes a controller, an AI controller, a frame memory, a register, and an image processing portion. The image processing portion is configured to receive image data from the frame memory and a parameter from the register, and to process the image data using the parameter. The frame memory is configured to retain the image data while power supply is stopped, and the register is configured to retain the parameter while power supply is stopped. The controller is configured to control power supply to the frame memory, the register, and the image processing portion. The AI controller is configured to predict when to switch into power gating and to provide a timing instruction to perform preparation operation for power gating.