Touch Controller ADC Circuit for Saturated Sample Processing
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Solution Overview
Problem
Touch screen systems face challenges in maintaining accurate touch position detection due to signal saturation caused by interference from sources like wireless charging, leading to invalid data points that require buffering or pausing processing, which increases hardware complexity and delays.
Innovation Solution
A multiply-accumulate circuit with dual multiplexer paths handles invalid ADC samples by substituting zero values during interference, accumulating coefficients, and seamlessly transitioning to regular operation when valid data returns, eliminating the need for buffering and maintaining consistent processing rates across channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If buffering or pausing processing is implemented to handle invalid ADC samples, then signal accuracy is preserved, but processing delays and hardware complexity increase
Solution Approach 1:
The system performs preliminary validation of ADC samples against saturation thresholds before they enter the main processing pipeline. When invalid samples are detected, the system proactively switches to alternative processing paths (using previously validated coefficients or default values) rather than waiting for buffer accumulation, thus preserving accuracy without time loss.
Solution Approach 2:
The invention extracts and handles invalid ADC samples separately from the main processing stream. By identifying saturated samples and removing them from the normal processing flow, the system can substitute alternative values without disrupting the continuous processing of valid samples, thereby maintaining both accuracy and processing speed.
2Measurement precision
If buffering is used to handle invalid ADC samples, then signal accuracy is maintained, but device complexity increases
Solution Approach 1:
The system extracts the validation and error-handling logic from the main processing path, using separate comparison circuits and conditional switching mechanisms. This allows invalid samples to be identified and handled without requiring complex buffering infrastructure in the critical signal path.
Solution Approach 2:
The processing system performs self-validation by automatically comparing each ADC sample against predefined saturation thresholds and autonomously selecting alternative processing paths when invalid data is detected, eliminating the need for external buffer management complexity.
3Measurement precision
If consistent sampling rates are maintained across all channels, then touch position detection accuracy is improved, but processing becomes vulnerable to interference from invalid samples
Solution Approach 1:
The system applies different processing qualities to different samples based on their validity. Valid ADC samples undergo full processing while invalid samples are detected and handled with alternative methods (substitution or skipping), allowing consistent sampling rates to be maintained without compromising overall signal integrity.
Solution Approach 2:
The system continuously monitors ADC samples against saturation thresholds and uses this feedback to dynamically adjust processing paths. When invalid samples are detected, the feedback mechanism triggers alternative processing modes, ensuring that touch position detection accuracy is maintained even in the presence of interference.
Data Source
AI summary
According to an embodiment, a signal processing circuit includes a coefficient accumulator and dual multiplexer paths for handling invalid ADC samples in touch controllers. When ADC samples exceed a saturation threshold, the circuit selects zero values through one multiplexer while accumulating coefficients through another multiplexer path. Upon receiving a first valid sample, the circuit multiplies it with accumulated coefficients before resuming normal coefficient processing. The architecture enables continuous processing across multiple touch sensor channels without buffering requirements while maintaining mathematical equivalence through the distributive property of multiplication.