Piezoelectric Resonator Terminal Layout for Capacitance Balance
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Solution Overview
Problem
Resonance devices with three or more upper electrodes often experience capacitance imbalance due to uneven electrode connection design, leading to variations in oscillation frequency when voltage signals are reversed.
Innovation Solution
A resonance device design where the first and second power supply terminals have different areas, ensuring that the capacitance between each terminal and the ground terminal is approximately equal, thereby balancing the capacitance and stabilizing oscillation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If three or more upper electrodes are used in the resonator, then the electrode connection design becomes more complex, but capacitance imbalance occurs between power supply terminals and ground terminal
Solution Approach 1:
The patent applies local quality by making the power supply terminals have different areas to compensate for capacitance imbalance. Specifically, when one power supply terminal connects to a larger total area of upper electrodes, that terminal is made physically larger to balance the capacitance to ground, while the other terminal is made smaller. This local adjustment of terminal areas resolves the capacitance balance issue while maintaining the flexibility to connect multiple upper electrodes.
2Manufacturing precision
If wiring line area and insulating film thickness determine capacitance, then capacitance is fixed by structure, but capacitance imbalance arises when connecting multiple upper electrodes
Solution Approach 1:
The patent applies parameter changes by modifying the area parameter of the power supply terminals. Instead of keeping all terminals with identical dimensions, the invention changes the area parameter of terminals based on their connection requirements. When a terminal connects to a larger total electrode area, its own area is increased proportionally to maintain equal capacitance to ground, thus resolving the imbalance while maintaining manufacturing precision.
3Productivity
If voltage signals are applied to power supply terminals, then the resonator operates, but oscillation frequency varies when capacitances are unbalanced
Solution Approach 1:
The patent applies equipotentiality by ensuring that both power supply terminals have equal capacitance to the ground terminal through careful design of their areas. This creates equipotential conditions during operation, where voltage signals applied to either terminal produce consistent electrical characteristics. The equal capacitance design ensures that the resonator operates reliably with stable oscillation frequency regardless of which terminal receives the voltage signal.
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
The design effectively suppresses capacitance imbalance, ensuring consistent oscillation frequency even when voltage signals are reversed, by varying the area of power supply terminals to match the capacitance between them and the ground terminal.
Implementation Method 1
a piezoelectric film formed between the lower electrode and the plurality of upper electrodes
Implementation Method 2
a capacitance formed between the first power supply terminal and the ground terminal is approximately equal to a capacitance formed between the second power supply terminal and the ground terminal
Data Source
AI summary
A resonance device is provided that includes a resonator including upper electrodes, a lower electrode, and a piezoelectric thin film formed therebetween. An upper cover is provided with a first surface facing the upper electrodes of the resonator. A power supply terminal is provided on a second surface of the upper cover with the power supply terminal electrically connected to the upper electrodes. Another power supply terminal is on the second surface of the upper cover and is electrically connected to the upper electrodes. A ground terminal is provided on the second surface of the upper cover and is electrically connected to the lower electrode. An area of each power supply terminal are different from one other such that a capacitance formed between the first power supply terminal and the ground terminal is approximately equal to a capacitance formed between the second power supply terminal and the ground terminal.