Demultiplexer Sample-Hold Circuits Reduce IC Count
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Solution Overview
Problem
Conventional demultiplexers for current-driven display devices, such as AMOLEDs, are inefficient in reducing the number of ICs required for data drivers while maintaining high-resolution display capabilities, as they prolong data programming time due to the need for alternately turning on and off switches.
Innovation Solution
The implementation of a demultiplexer using four sample/hold circuits that sequentially sample and hold data currents, allowing for simultaneous programming to multiple signal lines, reducing the number of ICs needed without significantly increasing data programming time through the use of sampling and holding switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional analog switches are used for demultiplexing data current, then the number of ICs in the data driver is reduced, but the data programming time is significantly increased
Solution Approach 1:
The demultiplexer is divided into multiple independent sample/hold circuits (first, second, third, and fourth circuits) that operate in parallel. Each circuit handles a specific data line independently, allowing simultaneous data programming to multiple lines without sequential switching delays.
Solution Approach 2:
The sample/hold circuits perform preliminary sampling of data currents during idle periods or when other circuits are programming data. This allows data to be pre-sampled and held ready for immediate programming, eliminating waiting time and enabling continuous operation without extending the overall programming cycle.
2Device complexity
If data is programmed to pixels sequentially through alternating switch operations, then the demultiplexer structure is simplified, but the resolution capability for high-definition displays is compromised
Solution Approach 1:
The demultiplexer is segmented into multiple independent sample/hold circuits, each capable of independently sampling and holding data for a specific data line. This segmentation enables parallel data programming to multiple pixels simultaneously, providing sufficient programming time for high-resolution displays while maintaining a relatively simple overall structure.
Solution Approach 2:
Each sample/hold circuit is designed as a universal module that can handle data sampling and holding for any data line. The circuits perform multiple functions: sampling incoming data currents, holding them at stable voltage levels, and providing them to data lines as needed. This multi-functionality allows the same circuit design to be replicated for multiple lines without increasing structural complexity.
Data Source
AI summary
A display device includes a demultiplexer. The demultiplexer programs time-divided and sequentially input data currents to at least two signal lines. The demultiplexer includes first and second sample/hold circuits for alternately sampling data currents and holding sampled data corresponding to the sampled data, and third and fourth sample/hold circuits for respectively sampling the sampled data held by the first and second sample/hold circuits and programming the current which correspond to the sampled data to the two signal lines.