Capacitance Detection Circuit Using Multi-Cycle Digital Charge Sensing
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Solution Overview
Problem
Current capacitance detection circuits rely on analog circuits, including analog-to-digital converters, which consume high power and are costly, and lack effective interference tolerance.
Innovation Solution
A capacitance detection circuit that digitizes capacitance without an analog-to-digital converter by using a capacitance control module to charge and discharge a capacitor multiple times, generating a digital voltage signal, and employing a filter module to obtain capacitance values, thereby simplifying the circuit structure and reducing power consumption while enhancing anti-interference ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an analog-to-digital converter is used to digitize capacitance, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces the analog-to-digital converter (a complex electronic system) with a purely digital counting method. The capacitor is charged through a known current source for a known time period, and the final voltage is converted to capacitance value using digital calculation (C = Q/V = I×t/V), eliminating the need for analog conversion circuitry entirely
Solution Approach 2:
The patent changes the measurement approach from direct analog voltage comparison to a time-based charging method where capacitance is determined by measuring the time required to charge the capacitor to a reference voltage, or by measuring the final voltage after a fixed charging time. This parameter transformation enables digital measurement without analog-to-digital conversion
2Measurement precision
If an analog-to-digital converter is used to digitize capacitance, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent eliminates the power-hungry analog-to-digital converter by substituting it with a digital calculation method that uses only simple current sources, voltage references, and timing circuits, dramatically reducing overall power consumption while maintaining measurement capability
3Measurement precision
If traditional capacitance detection circuit is used, then measurement capability is achieved, but anti-interference ability is insufficient
Solution Approach 1:
The patent employs periodic charging and discharging cycles of the capacitor, with each cycle consisting of a defined charging phase through a current source and a discharge phase. This periodic action allows for averaging multiple measurements and filtering out random noise and interference, significantly improving anti-interference ability
Solution Approach 2:
The patent uses feedback mechanisms where the measured capacitance value is compared against reference values or previous measurements, and the charging current or time is adjusted accordingly to maintain optimal measurement conditions and compensate for drift or interference effects
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 results in a simpler circuit structure, reduced power consumption, and improved interference tolerance by digitizing capacitance without the need for analog converters and increasing charge and discharge cycles.
Implementation Method 1
a capacitor to be detected is connected to the charge transfer module; the charge transfer module is configured to control the capacitor to be detected to be charged and discharged for multiple times
Data Source
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AI summary
The present disclosure provides a capacitance detection circuit, a sensor, a chip and an electronic device. The capacitance detection circuit includes a capacitance control module (1), a charge conversion module (2) and a filter module (3) which are connected with each other. The capacitance control module (1) controls a capacitor (Cx) to be detected to be charged and discharged for multiple times and generates a digital voltage signal according to an amount of received charges; where the capacitor (Cx) to be detected releases all stored charges after being charged to a preset voltage during each charge and discharge. In response to the digital voltage signal being at a high level, the charge conversion module (2) outputs negative charges with a preset charge amount to the capacitance control module (1), where the preset charge amount is greater than or equal to an amount of the stored charges when the capacitor (Cx) to be detected is charged to the preset voltage. The filter module (3) obtains a value representing a capacitance of the capacitor (Cx) to be detected according to the digital voltage signal generated after the capacitor (Cx) to be detected is charged and discharged for the multiple times. With the above solution, the capacitance of the capacitor to be detected may be digitized without an analog circuit such as an analog-to-digital converter, thereby realizing a simple circuit structure and reducing the power consumption and cost.