Capacitance-Ratio Band-Pass Filter for Stable Sensor Signal Q-Factor
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Solution Overview
Problem
Existing band pass filters face challenges in accurately setting parameters due to mismatches between resistors and capacitors, leading to fluctuations in Q-factor and other performance metrics.
Innovation Solution
A band pass filter design that determines parameters based on the capacitance ratio of capacitors, allowing for implementation with a single amplifier without resistor-capacitor mismatch, utilizing integrators and high pass filter converters to time-divisionally provide multiple conversion paths and adjust gain auxiliary components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional band pass filter design using resistor and capacitor is used, then filter parameters can be set, but parameter accuracy deteriorates due to mismatch between resistor and capacitor
Solution Approach 1:
The patent removes resistors from the band pass filter circuit and extracts only the capacitor elements, replacing resistance-based parameter setting with capacitance ratio-based parameter setting. This eliminates the mismatch problem between different component types (resistors and capacitors) while maintaining the ability to set filter parameters accurately.
Solution Approach 2:
The patent changes the fundamental parameter basis from resistance-capacitance product to pure capacitance ratio. By defining filter parameters (center frequency, Q-factor, gain) based on ratios of capacitor values rather than RC time constants, the system achieves better parameter accuracy and stability without relying on matching between different component types.
2Adaptability or versatility
If multiple amplifiers are used to implement buffer and variable gain, then filter functionality is improved, but device complexity increases
Solution Approach 1:
The patent makes a single amplifier perform multiple functions that traditionally required separate components. The same amplifier provides both the buffer function and the variable gain function by utilizing the capacitance ratio mechanism, eliminating the need for separate buffer amplifiers and reducing overall device complexity while maintaining full filter functionality.
Solution Approach 2:
The patent merges the buffer function and variable gain function into a single amplifier stage. By combining these functions and using the capacitance ratio approach, the design reduces the total number of amplifiers needed while preserving all necessary filter operations.
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 enables precise setting of Q-factor and gain independently, maintaining performance without the need for resistance elements, thus overcoming parameter mismatch issues and enhancing filter stability.
Implementation Method 1
a first integrator including a first amplifier; a first high pass filter converter connected to a first input terminal, a second input terminal and a first output terminal of the first amplifier
Implementation Method 2
the first high pass filter converter time-divisionally provides N (N is an integer greater than 1) high pass filter conversion paths
Implementation Method 3
parameters may be determined based on a capacitance ratio of capacitors, such that the band pass filter may be implemented with a single amplifier without any mismatch between the resistor and the capacitor
Data Source
AI summary
A sensor device includes: first sensors; second sensors which form capacitances with the first sensors; a sensor transmitter connected to the first sensors, where the sensor transmitter supplies driving signals to the first sensors; and a sensor receiver connected to the second sensors, where the sensor receiver receives sensing signals from the second sensors, and the sensor receiver includes a band pass filter which filters the sensing signals. The band pass filter includes: a first integrator including a first amplifier; a first high pass filter converter connected to a first input terminal, a second input terminal and a first output terminal of the first amplifier, where the first high pass filter converter time-divisionally provides N high pass filter conversion paths; and a first gain auxiliary component connected to the first input terminal and the first output terminal of the first amplifier while the first integrator performs an integral function.