Source Driver Interpolation for OLED Linearity
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Solution Overview
Problem
Existing OLED display drivers face challenges in achieving high-resolution output with minimal area while dealing with non-linear interpolation issues, leading to significant deviations from ideal linear voltage relationships.
Innovation Solution
A source driver method that includes a digital-to-analog converter and an output buffer with an interpolation function, where the output buffer averages non-linear and opposite interpolated voltage curves at different times to achieve a linear interpolated voltage characteristic, utilizing time-mixing and offset techniques to improve linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a 12-bit DAC is used to achieve high-resolution output, then the resolution is improved, but the area consumption increases significantly
Solution Approach 1:
The patent segments the 12-bit DAC into a 4-bit DAC and an output buffer that performs additional interpolation. The 4-bit DAC generates base voltage levels, and the output buffer interpolates these levels to achieve effective 12-bit resolution. This segmentation allows the actual DAC hardware to occupy minimal area while the interpolation function is implemented through switching and combining existing voltage levels.
Solution Approach 2:
The output buffer acts as an intermediary between the small 4-bit DAC and the OLED display. It takes the limited 4-bit digital input and through interpolation techniques (duplicating and combining voltage levels), produces output that effectively provides 12-bit resolution. This intermediary buffer resolves the contradiction by mediating between the small DAC area and the high resolution requirement.
2Area of stationary object
If interpolation is used to reduce area, then the area consumption is reduced, but the non-linear problem becomes more obvious
Solution Approach 1:
The patent employs periodic switching of the output buffer to generate interpolated voltage levels. By systematically switching between different input voltage combinations in a periodic sequence and averaging the results, the system achieves linear voltage output characteristics. This periodic action ensures that the interpolation process maintains linearity despite the reduced DAC resolution.
Solution Approach 2:
The patent changes the operating parameters of the output buffer, specifically controlling the switching timing and duration of different input voltage combinations. By adjusting these temporal parameters and the weighting of different interpolated levels, the system compensates for non-linearities and achieves improved voltage linearity while maintaining area reduction benefits.
Data Source
AI summary
A source driver including a digital-to-analog converter and an output buffer with an interpolation function is disclosed. A digital-to-analog converter converts a plurality of digital input voltages into a plurality of analog input voltages. The output buffer interpolates the analog input voltages. The output buffer outputs a first interpolated output voltage at a first time and a second interpolated output voltage at a second time respectively. A first interpolated voltage output curve of the first interpolated output voltage versus a digital input code and a second interpolated voltage output curve of the second interpolated output voltage versus the digital input code are both non-linear and opposite each other. The output buffer averages the first interpolated voltage output curve at the first time and the second interpolated voltage output curve at the second time to achieve a linear interpolated voltage characteristic.