Display DAC Gamma Decoder Gating for Lower Power Conversion
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Solution Overview
Problem
As display device resolution increases, the number of bits in digital image signals grows, leading to higher power consumption and increased capacity and element count for digital-analog converters, which is inefficient.
Innovation Solution
A digital-analog converter that reduces power consumption by turning off some gamma decoders in the global ramp using a ramp controller, which generates a ramp control signal based on the most significant bits of the digital image data to selectively disable gamma decoders during horizontal periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of bits of digital image signal increases to support higher resolution, then the resolution quality is improved, but power consumption and the number of elements in the digital-analog converter increase
Solution Approach 1:
The patent segments the global ramp into multiple independent gamma decoders (first gamma decoder, second gamma decoder, etc.), each handling a specific range of gray levels. This segmentation allows selective activation of only the necessary decoders based on the input digital signal range, reducing power consumption while maintaining high resolution capability.
Solution Approach 2:
The patent dynamically controls the operation of gamma decoders based on the input digital signal. The controller activates only the gamma decoders needed for the current signal range (e.g., only the first gamma decoder for lower gray levels, or both first and second decoders for higher gray levels), making the system adaptable and energy-efficient.
2Measurement precision
If the number of bits of digital image signal increases to support higher resolution, then the resolution quality is improved, but the capacity and number of elements in the digital-analog converter increase
Solution Approach 1:
The patent divides the digital-analog converter into multiple functional blocks (voltage divider, multiple gamma decoders, controller) that work together. Each gamma decoder handles a specific portion of the conversion task, allowing the system to achieve high resolution without requiring a single large, complex converter with all elements active simultaneously.
Solution Approach 2:
The controller dynamically configures the operational state of different gamma decoders based on the input signal characteristics. This dynamic control reduces the effective number of active elements at any given time, lowering the overall device complexity while maintaining the capability to handle high-bit digital signals.
3Reliability
If all gamma decoders are kept active to ensure complete signal coverage, then the signal conversion accuracy is improved, but power consumption increases
Solution Approach 1:
The controller dynamically adjusts which gamma decoders are active based on the input digital signal range. For example, when the input signal falls within the range handled by the first gamma decoder, only that decoder is activated. When the signal exceeds this range, the second gamma decoder is activated. This dynamic adaptation ensures accurate signal conversion while minimizing power consumption.
Solution Approach 2:
Each gamma decoder is designed with specific local characteristics optimized for its designated gray level range. The first gamma decoder is optimized for lower gray levels, while the second is optimized for higher gray levels. This local optimization ensures high conversion accuracy within each decoder's operational range while allowing selective activation to reduce overall power consumption.
Data Source
AI summary
A digital-analog converter of the disclosure converts digital image data to generate analog data signals. The digital-analog converter includes a voltage divider which generates a plurality of gamma reference voltages based on a first reference voltage and a second reference voltage; a global ramp including a plurality of gamma decoders which generates a plurality of global gamma voltages based on the gamma reference voltages; a decoder which selects one of the global gamma voltages according to the digital image data to generate the analog data signals; and a ramp controller which turns off at least some of the gamma decoders based on the digital image data.