Acoustic Wave Filter Circuit Layout for ESD and Harmonic Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Filter devices using acoustic wave elements are susceptible to damage from electrostatic discharge due to the potential for current flow between terminals, and interference waves can cause harmonics that superimpose as noise on the signal.
Innovation Solution
The filter device incorporates capacitors on each path connecting the signal terminals to the filter circuit, which helps to prevent electrostatic discharge damage and reduces harmonic interference by isolating the acoustic wave elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If signal terminals are electrically connected to each other in a filter device, then signal transmission is enabled, but current may flow between terminals due to electrostatic discharge causing damage to acoustic wave elements
Solution Approach 1:
A ground terminal is introduced as an intermediary between the first and second signal terminals. The ground terminal serves as a mediator that provides a safe discharge path for electrostatic current, preventing direct current flow between signal terminals that would damage the acoustic wave element. The ground terminal acts as a buffer that maintains signal transmission capability while protecting against electrostatic discharge.
2Adaptability or versatility
If multiple elements are provided on the front stage side and back stage side of the acoustic wave element, then filtering functionality is enhanced, but harmonics generated by interference waves are superimposed as noise on the signal
Solution Approach 1:
The harmful harmonics generated by interference waves are extracted and removed from the signal path using the ground terminal. The ground terminal provides a separate path that diverts harmonic interference away from the acoustic wave element and signal terminals, effectively separating the harmful frequency components from the useful signal transmission path.
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 configuration enhances the reliability of the filter device by protecting it from electrostatic discharge and minimizing noise interference, ensuring effective signal extraction.
Implementation Method 1
When the plurality of terminals are electrically connected to each other, a current larger than usual may flow between the plurality of terminals due to electrostatic discharge
Implementation Method 2
The first capacitor is provided on a first path connecting the first signal terminal and the filter circuit. The second capacitor is provided on a second path connecting the second signal terminal and the filter circuit
Data Source
AI summary
The filter device includes: a first body including an inductor and a capacitor; a second body that is mounted on the first body and that includes an acoustic wave element; a filter circuit including an inductor, a capacitor, and an acoustic wave element; a first capacitor; and a second capacitor. The first body further includes a first signal terminal and a second signal terminal. The filter circuit is, in a circuit configuration, provided between the first signal terminal and the second signal terminal. The first capacitor is provided on a first path connecting the first signal terminal and the filter circuit. The second capacitor is provided on a second path connecting the second signal terminal and the filter circuit.