Capacitance Sensing Circuit With Adjustable Threshold Measurement
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Solution Overview
Problem
Conventional capacitance sensing circuits are complex and costly, making them unsuitable for integration into integrated circuit chips like PMICs for applications such as battery detection and output capacitor detection.
Innovation Solution
A simplified capacitance sensing circuit design that includes a current pulse generator, voltage-to-current converter, comparator, resistor ladder, and processing unit to measure external capacitance with adjustable threshold voltages, allowing for a less complex and cost-effective implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitance sensing circuits are used, then measurement precision is achieved, but device complexity and cost increase
Solution Approach 1:
The circuit divides the capacitance measurement process into discrete stages using multiple comparators with different threshold voltages. Each comparator handles a specific voltage range, segmenting the overall measurement task to simplify individual circuit blocks while maintaining overall precision.
Solution Approach 2:
The patent uses multiple comparators with adjustable threshold voltages to measure capacitance. By changing the threshold voltage parameter across different comparison stages, the circuit achieves precise measurement without requiring a single complex high-precision comparator, thus reducing overall device complexity.
2Measurement precision
If conventional capacitance sensing circuits are used, then measurement precision is achieved, but manufacturing cost increases
Solution Approach 1:
The measurement function is segmented across multiple simple comparator blocks rather than requiring one complex precision circuit. This segmentation allows each component to be manufactured using standard, cost-effective processes while collectively achieving the required measurement precision.
Solution Approach 2:
By implementing adjustable threshold voltages through a resistor ladder network, the circuit achieves precise capacitance measurement across different ranges using simple, inexpensive components. This parameter adjustment mechanism is cost-effective to manufacture compared to fixed high-precision alternatives.
3Adaptability or versatility
If adjustable threshold voltage is implemented, then adaptability improves, but device complexity increases
Solution Approach 1:
The resistor ladder network serves multiple functions: it provides adjustable threshold voltages for different capacitance ranges, enables the same circuit to measure both small and large capacitance values, and allows a single circuit design to handle diverse measurement applications without requiring separate circuits for each function.
Solution Approach 2:
The circuit achieves adaptability by changing the threshold voltage parameter through the resistor ladder, allowing the same hardware to measure different capacitance values. This parameter adjustment is implemented using simple resistive dividers rather than complex voltage regulation circuits, maintaining low device complexity while improving versatility.
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
The design enables efficient and cost-effective capacitance measurement, facilitating integration into PMIC chips and providing accurate digital codes representing capacitance values.
Implementation Method 1
a current pulse generator configured to generate a current pulse to charge an external capacitor
Implementation Method 2
a voltage-to-current converter to convert a first voltage associated with the external capacitor to current to charge an internal capacitor
Implementation Method 3
a comparator operably connected to the internal capacitor to generate a toggle signal when a second voltage corresponding to the first voltage reaches an adjustable threshold voltage
Data Source
AI summary
A capacitance sensing circuit and method uses a current pulse to charge an external capacitor. A first voltage associated with the external capacitor is converted to current to charge an internal capacitor. A second voltage, which is associated with the internal capacitor that corresponds to the first voltage, is compared with an adjustable threshold voltage to generate a toggle signal. The adjustable threshold voltage is changed in response to the toggle signal, which is associated with a capacitance of the external capacitor.