Voltage Smoothing Circuit with Counter-Phase Multilayer Capacitors
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Solution Overview
Problem
Multilayer ceramic capacitors in voltage smoothing circuits generate distortion and vibration due to piezoelectric properties, leading to acoustic noise in electronic devices, which existing methods fail to completely eliminate despite driving capacitors in opposite phases.
Innovation Solution
A voltage smoothing circuit comprising a first and second multilayer capacitor connected in series with a regulator that calculates and adjusts voltages to minimize potential differences across each capacitor, using a correspondence table to output a first voltage that compensates for changes in the second voltage, thereby reducing residual distortion and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multilayer ceramic capacitors with large capacitance are used for power supply voltage smoothing, then the smoothing performance is improved, but vibration and acoustic noise are generated due to piezoelectric distortion
Solution Approach 1:
The patent divides a single large-capacitance capacitor into multiple smaller capacitors (first multilayer capacitor and second multilayer capacitor) connected in series. This segmentation reduces the voltage stress on each individual capacitor, thereby reducing piezoelectric distortion and the resulting acoustic noise while maintaining the overall smoothing performance through the combined capacitance effect.
Solution Approach 2:
The patent applies counter-phase driving to the first and second multilayer capacitors, where the distortion generated by one capacitor is compensated by the opposite distortion from the other capacitor. This is achieved by controlling the voltages such that when one capacitor experiences positive distortion, the other experiences negative distortion of equal magnitude, effectively canceling out the acoustic noise and vibration.
2Object-generated harmful factors
If multiple multilayer capacitors are driven in opposite phases to reduce acoustic noise, then noise suppression is improved, but distortion on output voltage increases due to incomplete cancellation
Solution Approach 1:
The patent employs a control mechanism that monitors the voltages across the first and second multilayer capacitors and adjusts them dynamically. By calculating the potential differences and comparing them against reference values, the system provides feedback control to optimize the counter-phase driving, ensuring both noise reduction and output voltage stability are achieved simultaneously.
Solution Approach 2:
The patent dynamically adjusts the voltage parameters applied to each capacitor based on their individual characteristics and the operating conditions. By changing the voltage magnitudes and phases according to real-time measurements, the system optimizes the distortion cancellation effect while maintaining stable output voltage, resolving the contradiction between noise suppression and voltage stability.
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
Significantly reduces or prevents acoustic noise and vibration of the circuit board by effectively canceling out distortions between the capacitors, even with non-linear voltage distortion curves.
Implementation Method 1
Ceramic materials used in the multilayer ceramic capacitor have piezoelectricity and an electrostrictive property. Accordingly, distortion is generated thereon when a voltage is applied.
Implementation Method 2
Ceramic materials used in the multilayer ceramic capacitor have piezoelectricity and an electrostrictive property. Accordingly, distortion is generated thereon when a voltage is applied.
Data Source
AI summary
A voltage smoothing circuit includes a first multilayer capacitor, a second multilayer capacitor, and a regulator including an input terminal electrically connected to the second multilayer capacitor and an output terminal electrically connected to the first multilayer capacitor. The regulator calculates a first voltage applied to the first multilayer capacitor based on a second voltage applied to the second multilayer capacitor from the input terminal such that a potential difference which is applied to the first multilayer capacitor decreases or increases when a potential difference which is applied to the second multilayer capacitor increases or decreases, and outputs the first voltage from the output terminal.