Hardware De-convolution Block for Multi-phase Touch Scanning
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Solution Overview
Problem
Conventional capacitance-sensing systems face challenges in improving signal-to-noise ratio (SNR) without decreasing refresh rate, particularly in multi-phase scanning of touch arrays, which requires significant processing load and can overwhelm central processing units (CPUs).
Innovation Solution
The implementation of a de-convolution circuit block that de-convolves convolved capacitance data from multi-phase scanning, reducing the processing load on CPUs by performing hardware-based de-convolution of capacitance maps, thereby improving SNR and processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-phase scanning is performed to improve signal-to-noise ratio, then measurement precision is improved, but device complexity increases due to significant processing load
Solution Approach 1:
The processing load is segmented by separating de-convolution operations into dedicated hardware circuitry independent from the main CPU. The touch sensor controller includes specific circuit blocks for performing de-convolution on capacitance data, dividing the overall processing function into specialized components that handle different aspects of touch detection independently.
Solution Approach 2:
A dedicated de-convolution hardware block acts as an intermediary between the capacitance sensing circuitry and the CPU. This intermediate hardware component performs the computationally intensive de-convolution operations, freeing the CPU from heavy processing loads while maintaining the ability to perform multi-phase scanning for improved signal-to-noise ratio.
2Productivity
If hardware de-convolution block is implemented to reduce CPU load, then productivity is improved, but device complexity increases
Solution Approach 1:
The touch sensor controller performs de-convolution operations autonomously using dedicated hardware blocks within the controller itself. The system serves its own processing needs by implementing self-contained de-convolution circuitry that operates independently without requiring external processing assistance, thereby improving productivity while keeping the overall system architecture integrated.
3Speed
If de-convolution is performed in hardware to maintain refresh rate, then speed is improved, but device complexity increases
Solution Approach 1:
The de-convolution hardware block is merged with the touch sensor controller architecture, integrating multiple functions (capacitance sensing, de-convolution, and touch detection) into a single unified controller. This consolidation allows the system to maintain high refresh rates by performing de-convolution in hardware without requiring separate dedicated processing units, thereby improving speed while managing device complexity through functional integration.
Data Source
AI summary
Apparatus and methods of de-convolution for multi-phase scans of an array of electrodes are described. One programmable circuit includes a sequencer to initiate a multi-phase transmit (TX) scan of an array of electrodes to obtain capacitance data. The capacitance data is stored in one or more storage devices as convoluted capacitance data. The programmable circuit also includes a digital circuit block to read the convoluted capacitance data from the one or more storage devices, de-convolve the convoluted capacitance data to obtain de-convoluted capacitance data, and store the de-convoluted capacitance data in the one or more storage devices.