Storage Device Capacitor Switching for Buzzing Noise Reduction
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Solution Overview
Problem
Electronic devices with multilayer ceramic capacitors connected to power-supply voltage lines experience buzzing noise due to resonance when the fluctuation frequency of the power-supply voltage matches the natural frequency of the device's mounting board, which is a concern in downsized devices requiring reduced noise levels.
Innovation Solution
A storage device with a power-supply voltage input terminal connected to both a fixed and a variable capacitor in parallel, where the number of conductive switches controlling the capacitors is adjusted to change the synthesis capacitance and switching frequency, preventing resonance and buzzing noise by ensuring the fluctuation frequency does not match the device's natural frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer ceramic capacitor is connected to a power-supply voltage line to stabilize voltage and filter noises, then power-supply stability is improved, but buzzing noise occurs when fluctuation frequency matches the natural frequency of the board
Solution Approach 1:
The patent employs a switchable capacitor configuration where capacitors can be dynamically connected or disconnected from the power-supply voltage line. This dynamic adjustment allows the system to change the total capacitance value, thereby shifting the fluctuation frequency away from the board's natural frequency and eliminating resonance-induced buzzing noise while maintaining power-supply stability.
Solution Approach 2:
The patent changes the electrical parameter (capacitance) by switching capacitors in and out of the circuit. By adjusting the total capacitance value, the fluctuation frequency of the power-supply voltage is modified to avoid matching the natural frequency of the mounting board, thus preventing resonance and buzzing noise while preserving voltage stabilization functionality.
2Object-generated harmful factors
If the fluctuation frequency is adjusted to avoid natural frequency and eliminate buzzing noise, then noise level is improved, but power-supply filtering effectiveness may be reduced
Solution Approach 1:
The system dynamically switches between different capacitor configurations to achieve optimal performance under different operating conditions. When buzzing noise is detected or anticipated, the switchable capacitors adjust the fluctuation frequency away from natural frequencies. When noise-free operation is maintained, the capacitors can be configured to maximize filtering effectiveness, thus dynamically balancing noise reduction and filtering performance.
Solution Approach 2:
The patent implements periodic monitoring and adjustment of the capacitor switching state based on detected buzzing noise or power-supply conditions. This periodic action allows the system to adaptively maintain both low noise levels and effective filtering by adjusting capacitor connections in response to changing operating conditions.
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 effectively cancels buzzing noise by adjusting the capacitance and switching frequency of the capacitors, preventing resonance and ensuring quiet operation even when natural frequencies are within the audible range.
Implementation Method 1
When the power-supply voltage fluctuates, the multilayer ceramic capacitor expands and contracts due to the electrostrictive effect.
Implementation Method 2
when the fluctuation frequency of the power-supply voltage matches the frequency (hereinafter referred to as a natural frequency) which is inherent to a vibration of the board, the board resonates and the vibration intensity of the board increases.
Data Source
AI summary
According to one embodiment, an electronic device includes a power-supply voltage input terminal, a first capacitor, and a second capacitor. The first capacitor has a fixed capacitance. The second capacitor has a variable capacitance. The first capacitor and the second capacitor are connected in parallel to the power-supply voltage input terminal.