Bidirectional Integrator Circuit for Wide-Range Capacitance Sensing
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Solution Overview
Problem
Current integrator circuit devices for touch and fingerprint sensors have limitations in measuring capacitance changes, particularly in expanding the measurable voltage range and are sensitive to variations in capacitance, which affects the Signal-to-Noise Ratio (SNR) and dynamic range.
Innovation Solution
The proposed integrator circuit device includes a bi-directional integration capability, controlled by a switching controller that changes integration direction based on output voltage thresholds, allowing for a wider dynamic range and improved robustness to sensor variations using a single readout amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional integrator circuit is used to measure capacitance changes in touch sensors, then the circuit can perform basic integration, but the measurable voltage range is limited and the circuit is sensitive to capacitance variations
Solution Approach 1:
The integrator circuit dynamically switches between positive and negative integration directions based on the output voltage level. When the output voltage reaches a threshold, the switching controller reverses the integration direction, allowing the circuit to adapt to varying capacitance conditions and expand the measurable voltage range beyond what a fixed-direction integrator could achieve.
Solution Approach 2:
The circuit changes the integration direction parameter (positive or negative) based on the output voltage threshold. This parameter switching enables the integrator to handle a wider range of input signals and compensate for capacitance variations, effectively expanding the measurable voltage range while maintaining measurement precision.
2Adaptability or versatility
If multiple readout amplifiers are used to handle varying capacitance conditions, then the dynamic range and robustness improve, but the power consumption and chip area increase
Solution Approach 1:
A single readout amplifier is designed to perform multiple functions by switching between positive and negative integration modes. This multi-functional approach allows one amplifier to handle various capacitance conditions that would traditionally require multiple dedicated amplifiers, thereby reducing power consumption while maintaining robustness to sensor variations.
Solution Approach 2:
The integrator circuit uses its own output voltage level to control the switching of integration direction through the switching controller. This self-regulating mechanism enables the single amplifier to automatically adapt to different operating conditions without requiring external control circuits or additional amplifiers, reducing overall power consumption.
3Adaptability or versatility
If multiple readout amplifiers are used to handle varying capacitance conditions, then the dynamic range and robustness improve, but the chip area increases
Solution Approach 1:
A single readout amplifier is designed to perform multiple functions by switching between positive and negative integration modes. This multi-functional approach allows one amplifier to handle various capacitance conditions that would traditionally require multiple dedicated amplifiers, thereby reducing chip area while maintaining robustness to sensor variations.
Solution Approach 2:
The patent combines the functionality of multiple potential amplifiers into a single readout amplifier by integrating the switching controller that manages bidirectional integration. This merging of functions reduces the total chip area required while maintaining the ability to handle varying capacitance conditions robustly.
4Device complexity
If the integrator integrates in a fixed direction, then the circuit is simpler, but the dynamic range is limited
Solution Approach 1:
The integrator transitions from a static, fixed-direction design to a dynamic, switchable design. The switching controller monitors the output voltage and automatically switches between positive and negative integration directions, expanding the dynamic range while adding only minimal control circuitry complexity.
Solution Approach 2:
The integration direction is periodically reversed based on threshold detection, creating a cyclic pattern of positive and negative integration. This periodic switching expands the dynamic range significantly compared to fixed-direction integration, while the control logic remains relatively simple due to the regular, predictable nature of the switching pattern.
Data Source
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AI summary
An integrator circuit device for integrating an input signal includes an integrator configured to perform integration on an input signal in a positive direction or a negative direction to generate an output voltage, and a switching controller configured to control a switch so that the integrator performs the integration on the input signal in the positive direction or the negative direction. The integrator circuit device further includes a counter configured to count a number of times an integration direction of the integrator is changed, and a controller configured to determine a final output voltage, based on the counted number of times the integration direction is changed and the output voltage.