Series-Resonator RF Filter Tuning With Stable Impedance
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Solution Overview
Problem
Existing RF filters require complex and costly production due to their multiplicity and complexity, and tunable filters alter important properties like insertion loss and impedance during tuning, limiting design flexibility.
Innovation Solution
The RF filter design incorporates series-interconnected basic elements with electroacoustic resonators and impedance converters, specifically impedance inverters, allowing for tuning without altering insertion loss and impedance, using only series resonators for stable performance and configuring filters as bandpass or band-stop with steep edges for duplexer applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional RF filters are used to support multiple frequency bands, then communication versatility is improved, but device complexity and production cost increase
Solution Approach 1:
The patent implements a universal filter module that can operate across multiple frequency bands by making the resonators tunable. The filter structure remains the same, but the resonant frequencies can be adjusted to support different transmission systems, allowing one filter to replace multiple conventional filters and reducing overall system complexity.
Solution Approach 2:
The filter incorporates tunable resonators whose resonant frequencies can be dynamically adjusted. This dynamic property allows the filter to adapt to different frequency bands and transmission systems, providing versatility while maintaining a single filter structure rather than requiring multiple fixed-frequency filters.
2Device complexity
If tunable RF filters are used to reduce filter multiplicity, then device complexity is reduced, but important filter properties such as insertion loss and impedance change during tuning
Solution Approach 1:
The patent employs series resonators whose key parameters (resonant frequency, antiresonant frequency, impedance, insertion loss) can be adjusted through controlled parameter changes. By using series resonators with adjustable capacitance or inductance values, the filter maintains stable electrical characteristics during tuning, as the series configuration preserves impedance continuity across the tuning range.
3Reliability
If series resonators are used instead of parallel resonators, then impedance stability during tuning is improved, but filter design flexibility is reduced
Solution Approach 1:
The patent uses dynamically tunable series resonators that can adjust their resonant and antiresonant frequencies while maintaining series configuration. This dynamic tuning capability within the series resonator structure provides both impedance stability and sufficient design flexibility to create bandpass or band-stop filters with steep edges for duplexer applications.
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 enables tunable RF filters with improved stability and flexibility in design, allowing for precise adjustment of resonant and antiresonant frequencies without affecting insertion loss or impedance, making them suitable for various communication band applications.
Implementation Method 1
basic elements each having an electroacoustic resonator
Implementation Method 2
The resonators of the basic elements are only series resonators. At least one of the resonators is tunable.
Data Source
AI summary
The specification relates to an RF filter in which characteristic filter variables have a decreased dependency on tuning. A filter in this case comprises series-interconnected basic elements that each have an electroacoustic resonator and impedance converters interconnected in series between the basic elements.