RF Filter Parallel Arm Circuit for Variable Attenuation Bands
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Solution Overview
Problem
Existing radio frequency modules with acoustic-wave filters face challenges in achieving variable attenuation characteristics as they are not adaptable to changes in multiband operations or signal frequency and power, leading to inadequate attenuation in specific bands without increased transmission loss.
Innovation Solution
A radio frequency module design incorporating a first and second inductor connected to a parallel arm resonator and a switch, allowing for variable attenuation by switching magnetic field coupling between the inductors to adjust attenuation bands and characteristics, while maintaining low transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed inductor is connected between the parallel arm resonator and ground to improve attenuation in a specific band, then the attenuation characteristics are improved, but the module cannot adapt to changes in multiband operations or signal frequency
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed inductor with a variable inductor that can adjust its inductance value based on the operating frequency band. The variable inductor is controlled by a control circuit that detects the input signal frequency and adjusts the inductance accordingly, enabling the filter to maintain optimal attenuation characteristics across multiple frequency bands and adapting to changing operational requirements.
2Adaptability or versatility
If multiple inductors are added to achieve variable attenuation for different bands, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent applies the universality principle by designing a control circuit that can manage multiple inductors using a single unified control mechanism. The control circuit detects the input signal frequency and selectively adjusts the appropriate inductor(s) to achieve the desired attenuation characteristics. This multi-functional control approach allows the system to handle multiple frequency bands and attenuation requirements without proportionally increasing overall circuit complexity.
3Reliability
If the inductance value is increased to improve attenuation in the attenuation band, then the attenuation is improved, but the inductor size increases
Solution Approach 1:
The patent applies the dynamics principle by using variable inductors that can adjust their inductance value electronically rather than requiring physically large fixed inductors. The variable inductor mechanism allows high inductance values to be achieved through magnetic core adjustment or electronic control, significantly reducing the physical size compared to traditional fixed inductors while maintaining the required attenuation performance across different operating conditions.
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 module provides adaptable attenuation characteristics across different frequency bands and power levels, ensuring effective signal cancellation with minimal loss, and reduces the size of the inductors and module through optimized magnetic field coupling.
Implementation Method 1
switching magnetic field coupling between the inductors to adjust attenuation bands and characteristics
Data Source
AI summary
A radio frequency module includes a filter having plural serial arm resonators and one or more parallel arm resonators, an inductor connected to a second path connecting an input/output terminal to the filter, and a parallel arm circuit connected between the ground and a first parallel arm resonator among the one or more parallel arm resonators. The parallel arm circuit includes inductors and a switch having a common terminal, selection terminals. The selection terminal is connected to a first end of the inductor. The selection terminal is connected to a first end of the inductor. The common terminal is connected to the first parallel arm resonator. The inductor and the inductor are connected, at their second ends, to the ground.