RF Front-End Filter Circuit With Fewer Parts and Lower Insertion Loss
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Solution Overview
Problem
Existing radio-frequency front end circuits for high frequency signals in multiple communication bands require a large number of circuit elements, leading to increased size and loss due to the need for impedance matching and isolation between filters.
Innovation Solution
A simplified configuration using fewer elastic wave filters and a series inductor and capacitor-based matching circuit, with capacitive coupling to a ground conductor, reduces the number of components and enhances isolation between frequency bands, allowing for a smaller and more efficient circuit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of circuit elements (inductors and capacitors) are used to ensure impedance matching and isolation between filters, then the filtering performance and isolation between frequency bands is improved, but the circuit size increases and insertion loss increases
Solution Approach 1:
The patent combines multiple filtering functions into a single elastic wave filter structure that can handle multiple frequency bands simultaneously. By integrating the filtering and impedance matching functions into one component rather than using separate inductors and capacitors for each function, the circuit achieves the required isolation and matching performance with fewer elements, directly reducing circuit size and complexity while maintaining reliability
Solution Approach 2:
The elastic wave filter is designed to perform multiple functions: it provides frequency-selective filtering for different communication bands, impedance matching between the antenna and filter, and isolation between frequency bands. This multi-functional design eliminates the need for separate dedicated components for each function, reducing the overall number of circuit elements while maintaining the required performance
2Reliability
If a large number of circuit elements are used to ensure impedance matching and isolation between filters, then the filtering performance is improved, but the circuit size increases
Solution Approach 1:
The patent merges the impedance matching function with the filtering function by designing the elastic wave filter with built-in matching capabilities. Instead of using separate inductor-capacitor networks for impedance matching alongside the filters, the matching is achieved through the filter's inherent structure and configuration, significantly reducing the space required for circuit elements while maintaining proper impedance matching across multiple frequency bands
3Reliability
If a large number of circuit elements are used in the filter configuration, then the isolation between first and second filter sides and third filter side is improved, but insertion loss increases
Solution Approach 1:
The patent combines multiple filtering stages and isolation functions into a single integrated elastic wave filter structure. By eliminating the need for separate inductors and capacitors that would be required in a traditional multi-stage filter design, the signal passes through fewer discrete components, reducing the cumulative insertion loss while maintaining the required isolation between different filter sides through the inherent properties of the elastic wave filter design
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 solution results in a compact radio-frequency front end circuit with reduced insertion loss and improved filter characteristics, enabling efficient demultiplexing of communication signals across multiple bands while minimizing circuit size and complexity.
Implementation Method 1
The first filter is connected between the input terminal and the first output terminal and allows a first communication signal to pass. The first filter is defined by an elastic wave filter.
Implementation Method 2
The third filter is a high pass filter including a first inductor and a capacitor
Implementation Method 3
The third filter is a high pass filter including a first inductor and a capacitor
Implementation Method 4
The second inductor is connected between the first filter and the input terminal
Data Source
AI summary
A radio-frequency front end circuit includes an input terminal, output terminals, a first filter, a third filter, and a matching inductor. The first filter is connected between the input terminal and the output terminal and allows a first communication signal in a low band to pass. The first filter is defined by an elastic wave filter. The third filter is connected between the input terminal and the output terminal and allows a third communication signal in a high band to pass. The third filter is defined by a high pass filter including an inductor and capacitors. The matching inductor is connected between the filter and the input terminal.