Hybrid Acoustic LC Filter Shielding Without Characteristic Degradation
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Solution Overview
Problem
The characteristics of high frequency modules, particularly those incorporating hybrid acoustic LC filters, can degrade when a metal electrode layer coupled to a ground terminal is formed as a shield layer.
Innovation Solution
The high frequency module includes a mounting substrate with a hybrid filter comprising an acoustic wave filter, inductors, and capacitors, covered by a resin layer and a metal electrode layer, with additional inductors coupled to signal terminals, enhancing the pass band width and suppressing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metal electrode layer coupled to a ground terminal is formed as a shield layer, then electromagnetic shielding is improved, but the characteristics of the hybrid filter degrade
Solution Approach 1:
A resin layer is introduced as an intermediary between the metal electrode layer (shield layer) and the hybrid filter. This resin layer acts as a mediator that prevents direct interaction between the shield layer and the acoustic wave resonator, thereby maintaining electromagnetic shielding effectiveness while preventing degradation of the hybrid filter characteristics. The resin layer isolates the acoustic wave resonator from the harmful electromagnetic fields generated by the shield layer.
2Adaptability or versatility
If the pass band width of the hybrid filter is increased, then signal transmission capability is improved, but the complexity of the filter structure increases
Solution Approach 1:
The pass band width of the hybrid filter is controlled by adjusting the resonant frequency and coupling coefficients of the acoustic wave resonators. By changing the physical parameters of the acoustic wave resonator (such as electrode dimensions, spacing, and material properties), the pass band width can be optimized without significantly increasing the number of resonators or the overall structural complexity. This allows for flexible bandwidth adjustment while maintaining a relatively simple filter architecture.
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 effectively suppresses the degradation of characteristics in high frequency modules, improving performance and reliability.
Implementation Method 1
an acoustic wave filter having at least one acoustic wave resonator
Implementation Method 2
acoustic wave resonator
Data Source
AI summary
To suppress degradation of characteristics, a high frequency module includes a mounting substrate, a first signal terminal, a second signal terminal, and ground terminals, and a hybrid filter. The hybrid filter is coupled between the first signal terminal and the second signal terminal. The hybrid filter includes an acoustic wave filter having at least one acoustic wave resonator, a first inductor, and a capacitor. The pass band width of the hybrid filter is larger than that of the acoustic wave resonator. A resin layer is disposed on a first principal surface of the mounting substrate. The resin layer covers at least part of the acoustic wave filter. A metal electrode layer covers at least part of the resin layer, and is coupled to the ground terminals. The second inductor is coupled between the hybrid filter and the second signal terminal.