Segmented Source Driver DAC for Gamma Curve Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The expansion of grayscales in modern display panels leads to increased area and cost for digital-to-analog converters (DACs) in display driver integrated circuits (DDICs, with differential difference amplifiers (DDAs) facing limited output voltage range due to linearity issues, hindering performance as grayscale values increase.
Innovation Solution
A source driver with a digital-to-analog converter (DAC) comprising m-bit and k-bit sub-DACs and an operational amplifier, which selects appropriate gamma voltages for different output voltage ranges to improve linearity and output accuracy of the differential difference amplifier (DDA).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of grayscales is increased to support wide color gamuts, then the output accuracy and linearity of the differential difference amplifier (DDA) deteriorate due to limited output voltage range
Solution Approach 1:
The patent divides the grayscale data codes into multiple segments, each processed by a dedicated sub-DAC (m-bit sub-DAC for first data codes, k-bit sub-DAC for second data codes). This segmentation allows each sub-DAC to handle a specific portion of the grayscale range with optimized precision, thereby maintaining output linearity across the full grayscale spectrum while supporting an increased total number of grayscales.
2Area of stationary object
If the area of digital-to-analog converters (DACs) is reduced to lower costs, then the output voltage range of the differential difference amplifier (DDA) is limited
Solution Approach 1:
The patent segments the DAC functionality into multiple sub-DACs (m-bit and k-bit sub-DACs) that process different portions of the data codes. This segmentation reduces the area requirement for each individual sub-DAC compared to a single high-resolution DAC, while the combined output of multiple sub-DACs extends the overall output voltage range of the DDA, thus achieving both area reduction and range expansion.
Solution Approach 2:
The patent extends the output voltage range by utilizing multiple dimensions of control through separate sub-DACs handling different data code portions. By combining the outputs of m-bit and k-bit sub-DACs in parallel, the system achieves an extended effective resolution and voltage range that would require a much larger single DAC, thereby expanding adaptability without proportionally increasing area.
3Area of stationary object
If the circuit area of the display driver integrated circuit (DDIC) is reduced, then the number of grayscales must be limited
Solution Approach 1:
The patent segments the DAC into multiple smaller sub-DACs (m-bit and k-bit) that can be arranged in a compact configuration within the DDIC. This segmentation allows the circuit to support a high number of grayscales using less total area compared to a single large high-resolution DAC, as each sub-DAC requires less area and they can be efficiently packed and shared across different grayscale ranges.
Data Source
AI summary
A source driver includes a digital-to-analog converter (DAC), comprising: a m-bit sub-DAC, configured to receive a plurality of first data codes within a plurality of data codes and generate a set of first intermediate voltages according to the plurality of first data codes; and a k-bit sub-DAC, configured to receive a plurality of second data codes within the plurality of data codes and generate a set of second intermediate voltages according to the plurality of second data codes; and an operational amplifier, configured to output a data voltage according to the set of first intermediate voltages or the set of second intermediate voltages; wherein m and k are positive integers.