Hybrid Filter Layout for Low-Parasitic High-Frequency Modules
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Solution Overview
Problem
High frequency modules with hybrid filters experience degradation in characteristics due to the formation of parasitic capacitance between metal electrode layers and signal terminals, leading to impedance mismatching and reduced insertion loss.
Innovation Solution
The high frequency module design includes a mounting substrate with a hybrid filter configuration, where the acoustic wave filter is mounted on one surface and inductors and capacitors are disposed on or in the substrate, with a resin layer covering the filter and a metal electrode layer connected to the ground, ensuring a longer distance between the signal terminals and the circuit elements to minimize parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metal electrode layer connected to a ground terminal is formed as a shield layer, then electromagnetic shielding is improved, but parasitic capacitance increases causing hybrid filter characteristics to degrade
Solution Approach 1:
A resin layer is introduced as an intermediary material between the metal electrode layer (shield layer) and the hybrid filter. This resin layer acts as a dielectric barrier that reduces parasitic capacitance formation while maintaining the electromagnetic shielding function of the metal electrode layer, thus preventing degradation of hybrid filter characteristics
Solution Approach 2:
The harmful effect of direct contact between the metal electrode layer and the hybrid filter is eliminated by extracting the problematic interaction and replacing it with a controlled dielectric interface through the resin layer, thereby removing the source of parasitic capacitance
2Volume of moving object
If the distance between signal terminals and circuit elements is reduced, then device size is minimized, but parasitic capacitance increases causing impedance mismatching
Solution Approach 1:
Different regions of the device are assigned different properties: the resin layer provides high dielectric strength and low loss characteristics in critical areas near signal terminals and circuit elements, while allowing closer spacing without increasing parasitic capacitance, thus enabling miniaturization while maintaining impedance matching precision
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 hybrid filter characteristics by reducing parasitic capacitance, maintaining impedance matching and improving insertion loss, thereby enhancing the overall performance of the high frequency module.
Implementation Method 1
The acoustic wave filter includes at least one acoustic wave resonator
Implementation Method 2
The hybrid filter includes an acoustic wave filter, a plurality of first inductors, and a plurality of first capacitors
Data Source
AI summary
A first filter is a hybrid filter including an acoustic wave filter, a plurality of first inductors, and a plurality of first capacitors. A high frequency module further includes a metal electrode layer covering at least part of a resin layer and at least part of an outer peripheral surface of a mounting substrate. Among a plurality of inductors including the plurality of first inductors of the first filter and a plurality of second inductors of a second filter, at least one inductor (the second inductor) is a circuit element including a conductor pattern portion formed in the mounting substrate. The shortest distance between the outer peripheral surface of the mounting substrate and a signal terminal (a third signal terminal) connected to the circuit element is longer than the shortest distance between the outer peripheral surface of the mounting substrate and the circuit element.