Display Data Driver DAC Buffering to Prevent Resistor String Loading
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Solution Overview
Problem
Existing data drivers in flat panel display devices experience load effects due to direct connections between resistor strings of digital-to-analog converters, leading to distorted voltage division and inefficiencies in current distribution.
Innovation Solution
Incorporation of pseudo amplifiers and main amplifiers with class AB controllers to separate current paths between digital-to-analog converters, ensuring each converter receives a stable reference current independently, thereby preventing load effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If digital-to-analog converters are directly connected with resistor strings, then device complexity is reduced, but load effects occur causing voltage division distortion and current distribution inefficiency
Solution Approach 1:
Pseudo amplifiers are introduced as intermediary components between the digital-to-analog converters and main amplifier. These pseudo amplifiers act as buffer stages that isolate the resistor strings from direct connection, preventing load effects while maintaining signal transmission. The pseudo amplifiers receive signals from multiple converters and condition them before passing to the main amplifier, thus resolving the contradiction between simple connection structure and stable voltage division.
2Device complexity
If multiple digital-to-analog converters share a common main amplifier, then device complexity is reduced, but current distribution efficiency deteriorates due to load effects
Solution Approach 1:
The amplifier system is segmented into two distinct functional blocks: pseudo amplifiers and main amplifier. Each digital-to-analog converter is assigned to a specific pseudo amplifier, creating dedicated signal paths. This segmentation allows each converter to have its own current path through the pseudo amplifier to the main amplifier, eliminating load effects and improving current distribution efficiency while maintaining overall system integration.
3Manufacturing precision
If resistor strings of digital-to-analog converters are directly connected, then manufacturing precision requirements are reduced, but voltage division distortion occurs leading to poor display quality
Solution Approach 1:
Pseudo amplifiers serve as intermediary buffering stages that isolate the resistor strings from direct interaction. By introducing these active components, the system achieves precise voltage division through active control rather than relying solely on passive resistor matching. This eliminates voltage division distortion caused by direct connections while maintaining manufacturing simplicity.
Data Source
AI summary
A data driver is disclosed that includes a first digital-to-analog converter, a second digital-to-analog converter, a third digital-to-analog converter, a first pseudo amplifier, a second pseudo amplifier, and a main amplifier. The first digital-to-analog converter includes a first resistor string including first resistors and a first decoder. The second digital-to-analog converter includes a second resistor string including second resistors and a second decoder, and is connected to the first digital-to-analog converter. The third digital-to-analog converter is connected to the second digital-to-analog converter. The first pseudo amplifier includes first and second driving transistors. The second pseudo amplifier includes third and fourth driving transistors. The main amplifier is connected to the first and second pseudo amplifiers, and is configured to generate a reference current. The second resistor string is connected between first and second nodes, and a first output node disposed between the first and second driving transistors is connected to the first node. A second output node disposed between the third and fourth driving transistors is connected to the second node.