Gamma Reference Voltage Circuit with Abnormal Current Sensing
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Solution Overview
Problem
Existing display devices lack effective mechanisms to sense abnormal outputs in gamma reference voltage circuits, leading to potential overcurrent issues that can damage the driving circuits.
Innovation Solution
A gamma reference voltage output circuit with operational amplifiers connected in a specific configuration, including transistors and sensing parts, to monitor current flow and output error signals when abnormal conditions are detected, protecting the display device from overcurrent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gamma reference voltage output circuit operates without sensing mechanism, then device complexity is reduced, but reliability deteriorates due to potential overcurrent damage
Solution Approach 1:
The sensing parts are integrated into the operational amplifier circuits before abnormal conditions occur, enabling proactive detection of overcurrent conditions. The connection nodes are pre-configured to allow current sensing through the power terminals, so that when abnormality occurs, the error signal is already ready to be generated and can immediately protect the circuit without requiring additional complex protection circuits.
2Reliability
If multiple operational amplifiers are connected with power terminal to output terminal configuration, then abnormal output sensing capability is improved, but device complexity increases
Solution Approach 1:
Each operational amplifier serves multiple functions: it generates gamma reference voltage, acts as a buffer, and simultaneously enables abnormal output sensing through its power terminal connections. The connection nodes allow the same operational amplifier structure to perform both voltage generation and current sensing functions, eliminating the need for separate sensing circuits and reducing overall system complexity despite the multi-functional requirements.
3Measurement precision
If sensing parts monitor current through transistors, then measurement precision of abnormal current is improved, but device complexity increases due to additional components
Solution Approach 1:
The sensing parts are merged with the operational amplifier circuits, sharing common transistors and connection nodes. The first and second transistors in each operational amplifier serve both the voltage generation function and the current sensing function. This merging allows accurate current measurement through the existing transistor structures without requiring separate dedicated sensing circuits, thereby maintaining measurement precision while minimizing additional complexity.
Data Source
AI summary
Discussed are a gamma reference voltage output circuit and a display device. The gamma reference voltage output circuit includes an (N)th operational amplifier configured to output an (N)th gamma reference voltage through an (N)th output terminal, where N is a natural number, an (N+1)th operational amplifier configured to output an (N+1)th gamma reference voltage being lower than the (N)th gamma reference voltage through its (N+1)th output terminal, an (N+2)th operational amplifier configured to output an (N+2)th gamma reference voltage being lower than the (N+1)th gamma reference voltage to an (N+2)th output terminal, and one or more connection nodes to which a power terminal of one of adjacent operational amplifiers in the (N)th operational amplifier, the (N+1)th operational amplifier, and the (N+2)th operational amplifier is connected to an output terminal of another operational amplifier.