Reconfigurable Touch Front-End Circuit for Low-Noise ADC
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Touch systems face challenges in accurately detecting touch events with reduced power consumption and area, particularly due to issues like parasitic noise and electromagnetic interference, especially as the size of sensor arrays increases, which affects detection time and accuracy.
Innovation Solution
A front-end circuit with a reconfigurable circuit configuration, including an amplifier, capacitors, and switches, that processes input signals by accumulating deviations between phases and converting them into digital signals, using a controller to manage the switches and capacitors across different operational periods to minimize noise and optimize signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size of sensor arrays is increased to improve touch detection coverage, then detection accuracy is improved, but parasitic noise and electromagnetic interference increase
Solution Approach 1:
The sensor array is divided into multiple sensor groups, with each group processed by a dedicated front-end circuit. This segmentation isolates noise sources within each group, preventing noise accumulation across the entire large array while maintaining comprehensive coverage through multiple distributed sensing zones.
Solution Approach 2:
The front-end circuit employs periodic switching between integration period and conversion period, with capacitors dynamically reconfigured at each phase. During integration, capacitors accumulate signal charges; during conversion, they transfer charges to digital output. This periodic operation enables noise filtering through synchronized sampling while maintaining continuous monitoring capability.
2Measurement precision
If complex circuit structures are used to improve signal processing capability, then detection accuracy is improved, but power consumption and area increase
Solution Approach 1:
Multiple functional operations are merged into a single front-end circuit per sensor group: the same amplifier and capacitor array perform both integration (signal accumulation) and conversion (digital output) functions by dynamic reconfiguration. This merging eliminates the need for separate dedicated circuits for each function, reducing total component count and power consumption while maintaining full processing capability.
Solution Approach 2:
The circuit employs dynamic reconfiguration of capacitor connections through switching elements, changing the circuit topology from integration mode to conversion mode based on operational phase. This dynamic adaptability allows a single static circuit structure to perform multiple functions that would otherwise require separate fixed circuits, reducing overall complexity and power usage.
3Measurement precision
If multiple capacitors are used for signal integration and conversion, then detection accuracy is improved, but circuit area increases
Solution Approach 1:
Each capacitor in the array is designed to serve multiple functions: during the integration period, capacitors accumulate signal charges from the amplifier; during the conversion period, the same capacitors transfer these charges to generate digital output signals. This multi-functionality eliminates the need for separate dedicated integration capacitors and conversion capacitors, reducing total capacitor count by approximately half while maintaining full signal processing capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate touch event detection with reduced power consumption and area, minimizing parasitic noise and electromagnetic interference, thus improving detection speed and accuracy while maintaining a simple circuit structure adaptable to varying sensor array sizes.
Implementation Method 1
a first capacitor configured to sample the input signal during the integration period and to sample an output voltage of the amplifier during the conversion period
Implementation Method 2
accumulate a deviation of the input signal between a first phase and a second phase as an accumulated deviation
Data Source
AI summary
A touch processing circuit includes: a front-end circuit including an amplifier, a first capacitor, a second capacitor, a third capacitor, and a plurality of switches each having two ends that are selectively connected each other, the front-end circuit being configured to process an input signal varying according to a touch; and a controller controlling the plurality of switches so that the front-end circuit is configured as a first circuit that accumulates deviation of the input signal between a first phase and a second phase during an integration period and a second circuit that converts the accumulated deviation into a digital signal during a conversion period.