Analog Front End Gain Calibration for RGB Channel Matching
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Solution Overview
Problem
Analog-to-digital converters in display systems suffer from gain and offset variations, leading to absolute accuracy distortion and channel mismatch issues, particularly in multi-channel systems like RGB color displays, where imperfect characteristics result in color shift phenomena.
Innovation Solution
An analog front end device comprising a conversion circuit with a clamper, multiplexer, voltage buffer, and analog-to-digital converter, along with a calibration unit that generates gain correction values to adjust and equalize the gain across multiple channels, thereby correcting gain mismatches and eliminating color shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog-to-digital converters are used in multi-channel display systems, then signal conversion capability is improved, but gain variation and channel mismatch occur leading to color shift
Solution Approach 1:
The patent applies preliminary action by performing gain calibration before normal display operation. A calibration unit generates test signals and measures actual gain values of each channel, storing correction values in advance. This pre-calibration approach eliminates color shift issues before they occur during actual image display, resolving the contradiction between maintaining signal conversion capability and ensuring gain accuracy.
Solution Approach 2:
The patent implements feedback through a calibration unit that measures the actual gain values of each analog-to-digital converter channel and generates correction values based on measured deviations from expected gain. This feedback mechanism continuously monitors and corrects gain variations, maintaining measurement precision while preserving the signal conversion capability of the analog-to-digital converters.
2Adaptability or versatility
If multiple analog-to-digital converters are used for different channels, then multi-channel signal processing capability is improved, but channel mismatch and color shift phenomena occur
Solution Approach 1:
The patent applies preliminary action by performing inter-channel gain calibration before normal operation. The calibration unit measures gain values across all channels using test signals and generates channel-specific correction values that compensate for manufacturing variations. This pre-calibration ensures all channels are properly matched before processing actual multi-channel display signals, eliminating color shift while maintaining multi-channel processing capability.
Solution Approach 2:
The patent changes the gain parameter of each channel dynamically based on measured values. The calibration unit determines actual gain values for each analog-to-digital converter channel and applies correction values to adjust the gain parameters. This parameter adjustment compensates for manufacturing tolerances and ensures consistent channel matching, resolving the contradiction between multi-channel versatility and channel matching precision.
3Measurement precision
If calibration processes are added to correct gain variations, then gain accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a calibration unit that can calibrate all analog-to-digital converter channels using a single test signal generation mechanism. The same calibration circuitry and processing logic are used across all channels, reducing overall system complexity while achieving accurate gain correction for each channel. This multi-functional approach improves gain accuracy without proportionally increasing device complexity.
Data Source
AI summary
The invention discloses an analog front end device includes a calibration unit and at least a conversion circuit. The conversion circuit includes a clamper, a multiplexer, an voltage buffer and an analog to digital converter. The clamper receives an image signal and resets the DC voltage level of the image signal to generate a clamped signal. The multiplexer receives the clamped signal and a test signal and outputs the clamped signal or the test signal according to a selecting signal. The voltage buffer amplifies the clamped signal or the test signal to generate a buffer signal. The analog to digital converter converts the buffer signal into a digital signal. The calibration unit generates a gain correction value according to the test signal and calibrates the gain offset of the digital signal according to the gain correction value.