Comparator Measurement Circuit for Indirect Passive Component Sensing
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Solution Overview
Problem
There is a lack of effective solutions for measuring the capacitance or resistance of passive components, especially when direct measurement from terminals is not possible, such as in capacitive or resistive touch devices.
Innovation Solution
A measurement circuit comprising comparators and a counter is used to generate comparison signals and count pulses, allowing for the estimation of capacitance or resistance by controlling voltage drops across capacitors and resistors, leveraging known resistors and capacitors for calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct measurement from terminals is attempted, then measurement simplicity is improved, but measurement accuracy deteriorates due to inability to access internal characteristics
Solution Approach 1:
The patent introduces an intermediary measurement system that connects to the passive component through available terminals. This system uses known resistors and capacitors as mediators to indirectly determine the unknown capacitance value by measuring voltage drop times, thereby achieving accurate measurement without direct internal access to the component.
2Measurement precision
If complex measurement systems are implemented to achieve accurate capacitance measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The measurement system is segmented into distinct functional modules: voltage generation unit, comparison units (first and second comparators), timing unit (counter), and control logic. Each module performs a specific function, making the overall complex system manageable and easier to implement with standard electronic components while maintaining high measurement precision.
Solution Approach 2:
The patent employs periodic charging and discharging cycles of capacitors, with each cycle generating comparison signals that are counted over time. This periodic action transforms the continuous measurement problem into discrete, countable events, simplifying the measurement process while achieving accurate capacitance determination through time-based counting.
3Measurement precision
If time-based voltage drop measurement is used, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The patent performs preliminary charging of capacitors to known voltage levels before the actual measurement begins. This preliminary action establishes a consistent starting condition for each measurement cycle, allowing the subsequent voltage drop time to be directly correlated with capacitance value without requiring additional calibration or setup time during the actual measurement process.
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 method enables accurate measurement of passive component characteristics, such as capacitance or resistance, by analyzing the time it takes for voltages to drop, effectively addressing the challenge of indirect measurement in touch devices.
Implementation Method 1
The first comparator is used to compare a first voltage and a first reference voltage to generate a first comparison signal
Implementation Method 2
The second comparator is used to compare a second voltage and a second reference voltage to generate a second comparison signal
Implementation Method 3
The third comparator is used to compare a third voltage and a third reference voltage to generate a third comparison signal
Implementation Method 4
The counter is used to count number of pulses according to the third comparison signal. The number of pulses corresponds to time for the third voltage to drop to the third reference voltage
Data Source
AI summary
A circuit for measuring a passive component includes a first comparator, a second comparator, a third comparator and a counter. The first comparator compares a first voltage and a first reference voltage to generate a first comparison signal. The second comparator compares a second voltage and a second reference voltage to generate a second comparison signal. The third comparator compares a third voltage and a third reference voltage to generate a third comparison signal. The counter counts the number of pulses according to the third comparison signal. The number of pulses corresponds to time for the third voltage to drop to the third reference voltage, and the first comparison signal and the second comparison signal are used to control the drop of the third voltage.