Automatic Trimming of PCB-Based LC Circuit Frequency
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Solution Overview
Problem
The manufacturing variations in PCB-based LC circuits lead to frequency inconsistencies in touch and proximity sensors, requiring time-consuming and costly adjustments of surface-mount capacitors, which are often imprecise and inefficient.
Innovation Solution
An apparatus and method for automatically trimming the capacitance of a PCB-based LC circuit using a variable capacitor and an adjustment circuit that compares the LC circuit frequency to a reference frequency, adjusting the capacitance to match the desired frequency, thereby stabilizing the LC circuit frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface-mount capacitors are manually adjusted to account for manufacturing variations, then frequency precision is improved, but production time and cost increase significantly
Solution Approach 1:
The patent applies preliminary action by incorporating a variable capacitor and adjustment circuit into the LC circuit during manufacturing, enabling automatic frequency trimming before final assembly. This preliminary setup allows for precise frequency adjustment without requiring time-consuming manual capacitor replacement during production
Solution Approach 2:
The patent implements self-service through an automatic frequency trimming system where the adjustment circuit autonomously measures the LC circuit frequency and adjusts the variable capacitor to achieve the target frequency. This eliminates the need for manual intervention and repetitive capacitor replacement, significantly reducing production time while maintaining frequency precision
2Manufacturing precision
If surface-mount capacitors are repeatedly soldered and de-soldered to adjust frequency, then frequency accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The variable capacitor and adjustment circuit are incorporated into the LC circuit during the initial manufacturing process, establishing a foundation for automatic frequency trimming. This preliminary integration eliminates the need for costly repeated capacitor replacements and re-soldering operations
Solution Approach 2:
The patent replaces the mechanical process of manually replacing surface-mount capacitors with an electronic automatic adjustment system. The adjustment circuit electronically controls the variable capacitor to achieve frequency tuning, substituting costly manual mechanical operations with automated electronic control
3Stability of the object's composition
If inductors with high tolerances are used to reduce frequency variations, then frequency stability is improved, but component cost increases significantly
Solution Approach 1:
The patent applies dynamics by replacing static high-tolerance inductors with a dynamic frequency adjustment system. The variable capacitor and adjustment circuit actively tune the LC circuit frequency to compensate for component variations, achieving frequency stability through dynamic adjustment rather than relying on expensive high-tolerance passive components
Solution Approach 2:
The patent implements parameter changes by modifying the capacitance value of the variable capacitor to compensate for inductor tolerance variations. This allows the system to maintain stable frequency performance by adjusting the capacitance parameter in response to measured frequency deviations, avoiding the need for expensive high-tolerance inductors
4Manufacturing precision
If manual capacitor replacement is used to trim LC circuit frequency, then frequency precision is improved, but automation level remains low
Solution Approach 1:
The adjustment circuit autonomously performs frequency measurement and capacitor adjustment without external intervention. The system automatically compares the measured frequency with the target frequency and adjusts the variable capacitor accordingly, achieving high-frequency precision while maintaining full automation throughout the trimming process
Solution Approach 2:
The patent implements feedback through a closed-loop frequency measurement and adjustment system. The frequency comparator continuously monitors the LC circuit frequency and provides feedback to the adjustment circuit, which modifies the variable capacitor to minimize frequency error, achieving precise frequency control through automated feedback control
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 solution enables precise and efficient adjustment of the LC circuit frequency, reducing manufacturing variations and improving the accuracy and cost-effectiveness of touch and proximity sensors by automatically trimming the capacitance, thus enhancing the reliability and performance of inductive positioning systems.
Implementation Method 1
The variable capacitor may be connected in parallel to the PCB capacitor through the interface. The adjustment circuit may be further configured to increase the capacitance of the variable capacitor to increase the effective capacitance of the LC circuit
Implementation Method 2
The adjustment circuit may include a frequency comparator circuit configured to compare the LC circuit frequency against a reference frequency
Data Source
AI summary
Apparatus and methods of automatically trimming a PCB-based LC circuit. The apparatus may comprise an interface to a printed circuit board (PCB). The PCB may include a PCB inductor and a PCB capacitor to form an LC circuit. The LC circuit may have an LC circuit frequency. The apparatus may comprise a variable capacitor communicatively coupled to the interface and configured to adjust an effective capacitance of the LC circuit.