Voltage Generator Segmentation for LCD Source Drivers
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Solution Overview
Problem
Existing gamma reference voltage generators for liquid crystal display source drivers suffer from noise issues due to poor power supply rejection ratio (PSRR) and have large size due to multiple DAC blocks required for generating various voltage levels.
Innovation Solution
A voltage generator comprising a reference block and digital-to-analog conversion blocks, where the reference block provides fractional parts of the supply voltage to the DAC blocks, and the covering range of output voltages is optimized to reduce circuit size and noise immunity, using filter and buffer circuits to isolate noise and reduce the range of output voltages generated by each DAC block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple DAC blocks are used to generate various voltage levels, then the voltage generator can provide comprehensive output voltage ranges, but the circuit size becomes large
Solution Approach 1:
The patent divides the voltage generation task into segments by allocating different output voltage ranges to different DAC blocks. Each DAC block is responsible for a specific voltage range, and the reference block provides corresponding reference voltages for each segment. This segmentation allows the system to cover a comprehensive voltage range while keeping each individual DAC block compact, thereby reducing the overall circuit size.
2Device complexity
If the power supply device is used directly, then the voltage generator can operate with simple power supply, but noises occur due to poor power supply rejection ratio
Solution Approach 1:
The patent introduces an intermediary mechanism where the reference block generates reference voltages that are derived from the power supply voltage but are designed to be less sensitive to power supply noise. These reference voltages serve as mediators between the power supply and the DAC blocks, isolating the noise and providing stable reference levels for voltage generation.
3Area of stationary object
If the covering range of each DAC block is reduced, then the circuit size is minimized, but the ability to generate all required voltage levels may be compromised
Solution Approach 1:
The patent segments the overall voltage range into multiple sub-ranges, with each DAC block assigned to a specific segment. The reference block provides multiple reference voltages corresponding to each segment, enabling each DAC block to operate within its optimized, smaller voltage range while the combination of all DAC blocks covers the complete required voltage spectrum.
Data Source
AI summary
A voltage generator for providing a plurality of output voltages having different levels includes: a reference block and a plurality of digital-to-analog conversion blocks. The reference block is employed for providing a plurality of reference voltages according to a supply voltage. The plurality of digital-to-analog conversion blocks is coupled to the reference block, and each of the digital-to-analog conversion blocks receives the reference voltages and generates a digital-to-analog output voltage according to a digital code, wherein digital-to-analog output voltages generated by the digital-to-analog conversion blocks have different levels, respectively. In addition, a range of the digital-to-analog output voltage generated by a first digital-to-analog conversion block of the digital-to-analog conversion blocks is different from that of the digital-to-analog output voltage generated by a second digital-to-analog conversion block.