Display Amplifier Offset Compensation for Low-Frequency Uniformity
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Solution Overview
Problem
Existing display technologies face challenges in compensating for amplifier offsets, which affect display resolution and uniformity, particularly in low-frequency display modes, leading to increased chip size and cost, and existing chopping methods are inefficient for low-power driving.
Innovation Solution
A display driving circuit with a first decoder and a second decoder selecting input and reference voltages, a first and second amplifier performing amplification and comparison operations, and processing circuitry determining compensation values to set the second amplifier to an opposite polarity of the first amplifier, thereby compensating for offsets during calibration sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amplifier offset compensation is implemented using existing chopping methods, then display uniformity can be improved, but chip size and cost increase
Solution Approach 1:
The patent combines the offset compensation function with the existing amplifier structure by utilizing the same amplifier circuit for both signal amplification and offset compensation. The compensation is achieved through calibration sequences that reuse existing hardware components (amplifiers, decoders, and processing circuitry) rather than adding separate compensation circuits, thereby avoiding chip size increase while maintaining display uniformity
Solution Approach 2:
The amplifier circuit performs self-compensation for its own offset errors through calibration sequences. The processing circuitry determines compensation values by having the amplifier operate in calibration mode and compare its output against reference values, allowing the system to automatically correct its own deficiencies without external intervention or additional hardware
2Manufacturing precision
If amplifier offset compensation is implemented using existing chopping methods, then display uniformity can be improved, but device cost increases
Solution Approach 1:
The patent merges the offset compensation functionality into the existing display driving circuit architecture. By using the same amplifiers, decoders, and processing circuitry for both normal operation and calibration/compensation functions, the invention avoids additional manufacturing costs that would arise from adding separate compensation hardware components
Solution Approach 2:
The existing amplifier and processing circuitry are designed to perform multiple functions: normal signal amplification during display operation and offset compensation during calibration sequences. This multi-functionality eliminates the need for dedicated compensation hardware, thereby reducing device cost while achieving improved display uniformity
3Manufacturing precision
If conventional calibration methods are used, then amplifier offsets can be compensated, but comparison operation uniformity deteriorates
Solution Approach 1:
The patent inverts the traditional calibration approach by having the amplifier under test perform the comparison operation against reference amplifiers, rather than having reference amplifiers test the device under test. This inversion ensures that all amplifiers operate in identical comparison modes, improving the uniformity and reliability of the calibration process while achieving effective offset compensation
Data Source
AI summary
A display device includes a first decoder configured to select a first input voltage based on one or more gamma voltages during a first calibration sequence of a plurality of calibration sequences, a first amplifier configured to generate and output a first output voltage during the first calibration sequence, the first output voltage generated by amplifying the first input voltage, a second decoder configured to select one or more first reference voltages based on the one or more gamma voltages during the first calibration sequence, a second amplifier configured to output a first comparison result during the first calibration sequence based on the first output voltage and the one or more first reference voltages, and processing circuitry configured to determine a first compensation value based on the first comparison result during the first calibration sequence, the first compensation value compensating for a first offset of the first output voltage.