Multi-Electrode Sampling Circuit with Shared Residue ADC
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Solution Overview
Problem
Existing capacitive sensing technologies for proximity detection are sensitive to parasitic capacitors and face limitations in measuring a large number of capacitors simultaneously due to physical constraints, leading to inaccurate measurements and reduced resolution.
Innovation Solution
The proposed solution involves a sampling circuitry with multiple charge amplifiers and modulators for each electrode, a multiplexer for residue signals, and a common residue ADC, allowing parallel sampling and digital summation to increase averaging and reduce noise, thereby improving measurement accuracy and resolution while minimizing area requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple capacitors are measured simultaneously using conventional techniques, then measurement coverage increases, but measurement precision deteriorates due to parasitic capacitor interference and noise
Solution Approach 1:
The patent divides the measurement system into multiple independent measurement channels, each with its own charge amplifier and modulation circuit. Each channel measures one capacitor independently, preventing parasitic capacitor interference from affecting other measurements. This segmentation allows simultaneous measurement of multiple capacitors while maintaining high precision in each channel.
Solution Approach 2:
The patent employs periodic modulation of the excitation voltage at different frequencies for each measurement channel. By modulating at distinct frequencies and using synchronous detection, the system can distinguish between signals from different capacitors and reject noise and parasitic effects. This periodic action with frequency discrimination enables simultaneous multi-capacitor measurement with high precision.
2Quantity of substance
If more measurement channels are added to increase the number of measurable capacitors, then measurement capacity increases, but device complexity increases
Solution Approach 1:
The patent designs each measurement channel to be identical and reusable, with universal components such as charge amplifiers, modulators, and demodulators. This modular universal design allows the system to scale to multiple channels without proportionally increasing overall complexity, as each channel follows the same standardized architecture.
Solution Approach 2:
The patent combines multiple measurement channels into a single integrated system with shared power supply, control logic, and signal processing resources. By merging common functions at the system level while keeping measurement channels independent, the patent reduces overall device complexity compared to having completely separate measurement systems for each capacitor.
3Area of stationary object
If conventional single-channel measurement is used, then device area is minimized, but productivity decreases due to sequential measurement requirements
Solution Approach 1:
The patent segments the measurement function into parallel channels that operate simultaneously. Each channel is a compact module that can be replicated, allowing multiple capacitors to be measured at the same time rather than sequentially. This segmentation enables productivity improvement while controlling area through efficient layout of identical modules.
Solution Approach 2:
The patent transitions from sequential measurement (one dimension in time) to parallel measurement (adding spatial dimension with multiple channels). By arranging measurement channels in parallel rather than series, the system measures multiple capacitors simultaneously, dramatically increasing productivity without requiring excessive chip area due to the compact nature of each channel.
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 enhances the accuracy and resolution of capacitive sensing by averaging more modulation cycles per electrode, effectively reducing noise and perturbations, and allows for a larger number of electrodes to be measured without increasing chip size significantly.
Implementation Method 1
a plurality of charge amplifiers and a plurality of modulators, wherein each charge amplifier and each modulator, comprised in said plurality of charge amplifiers and said plurality of modulators respectively, corresponds to an electrode of said plurality of electrodes
Implementation Method 2
each modulator generates a residue signal and a rough code corresponding to each sampled electrode of said plurality of electrodes
Data Source
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AI summary
A sampling circuitry for a plurality of electrodes the circuitry comprising a plurality of charge amplifiers and a plurality of modulators, wherein each charge amplifier and each modulator, comprised in the plurality of charge amplifiers and the plurality of modulators, respectively, corresponds to an electrode of the plurality of electrodes, wherein each modulator is capable of generating a residue signal and a rough code corresponding to each sampled electrode of the plurality of electrodes, a multiplexer capable of receiving a plurality of residue signals generated by the plurality of modulators, a residue analog to digital converter capable of receiving a multiplexed residue signal from the multiplexer and outputting a digitized multiplexed residue signal, and a digital summation circuitry capable of receiving the digitized multiplexed residue signal and a plurality of rough codes, comprising each rough code corresponding to each sample electrode, and outputting a plurality of output codes.