OLED Sensing Gain Amplifier Cells for Inter-Channel Error Reduction
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Solution Overview
Problem
The existing gain amplifiers in OLED display systems suffer from inter-channel errors, which decrease the operating efficiency of the sensing circuit, affecting the accuracy of image compensation and overall display performance.
Innovation Solution
A gain amplifier design featuring a plurality of gain amplifier cells sequentially coupled to an operational amplifier, utilizing capacitors between internal nodes to determine voltage gain and DC offset without considering parasitic capacitance, and incorporating a differential voltage input and output scheme to cancel common mode noise, along with a reset circuit to prevent memory effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If traditional gain amplifier cells are used with shared operational amplifier, then circuit hardware area and power consumption are reduced, but inter-channel errors increase
Solution Approach 1:
The gain amplifier is divided into multiple independent gain amplifier cells (first gain amplifier cell, second gain amplifier cell, etc.), each processing signals from different sensing lines. This segmentation allows each cell to independently amplify signals without mutual interference, eliminating inter-channel errors while maintaining the shared operational amplifier architecture for power efficiency.
2Device complexity
If gain amplifier shares operational amplifier among multiple channels, then device complexity is reduced, but inter-channel error increases
Solution Approach 1:
The sensing circuit is segmented into multiple independent gain amplifier cells, each dedicated to a specific sensing line. This segmentation maintains circuit simplicity by sharing the operational amplifier while ensuring measurement precision through isolated signal processing paths that prevent inter-channel interference.
Solution Approach 2:
Each gain amplifier cell performs preliminary amplification of its designated sensing line signal before the signals are further processed. This preliminary action ensures that each channel's signal is properly conditioned independently, preventing inter-channel errors from affecting subsequent processing stages.
3Ease of manufacture
If conventional capacitor placement is used in gain amplifier cell, then parasitic capacitance affects voltage gain and DC offset, but manufacturing becomes simpler
Solution Approach 1:
The critical capacitors (first capacitor and second capacitor in each gain amplifier cell) are extracted and placed outside the gain amplifier cell boundary, connected to the output node of the operational amplifier. This extraction removes these capacitors from the vulnerable internal node environment where parasitic capacitance would affect their values, ensuring precise voltage gain and DC offset control while maintaining ease of manufacture through standardized external connections.
Data Source
AI summary
A gain amplifier of a sensing circuit for sensing degradation of an OLED display panel, the gain amplifier comprising: an operation amplifier; and a plurality of gain amplifier cells sequentially coupled to the operation amplifier. Each of the gain amplifier cells comprises a plurality of capacitors each placed between two internal nodes of the gain amplifier cell, excluding a ground node, such that a voltage gain of the gain amplifier and a DC offset of the gain amplifier are determined according to capacitances of the capacitors without considering parasitic capacitance.