Diplexer Miniaturization via Integrated Resonator and Matching Circuit
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Solution Overview
Problem
Conventional diplexers incorporating multiple resonators for bandpass filters are difficult to miniaturize, leading to unwanted coupling and stray capacitance, which degrades isolation and generates spurious signals.
Innovation Solution
A diplexer design that includes a first bandpass filter with multiple resonators and a second bandpass filter composed of a single resonator and a series resonant circuit, or a parallel resonant circuit formed by an inductor and stray capacitance, reducing the number of elements and preventing unwanted coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple resonators are used in both bandpass filters, then filtering performance is improved, but device size increases and element density causes unwanted coupling
Solution Approach 1:
The patent merges the matching element and the second bandpass filter into a single integrated structure. The matching element is formed by a transmission line that directly connects to the second resonator, eliminating the need for separate matching components. This integration reduces the total number of discrete elements while maintaining both the filtering performance and the impedance matching functionality.
Solution Approach 2:
The transmission line serving as the matching element also functions as part of the second bandpass filter structure. By making the matching element multi-functional, the patent reduces the overall element count and minimizes the space required, thereby achieving compact diplexer design without compromising filtering performance.
2Volume of stationary object
If device is miniaturized, then diplexer size is reduced, but elements are brought closer causing unwanted coupling and stray capacitance
Solution Approach 1:
By integrating the matching element with the second bandpass filter, the patent reduces the number of discrete elements that could potentially couple unwantedly. The merged structure minimizes inter-element spacing and reduces stray capacitance, enabling compact design without the harmful effects of element proximity.
Solution Approach 2:
The patent extracts and eliminates unnecessary separate matching elements from the conventional design. By removing these redundant components and integrating their function into the transmission line structure, the patent reduces the source of unwanted coupling and stray capacitance while maintaining the required impedance matching.
3Reliability
If multiple matching elements and bandpass filters are provided, then signal separation performance is improved, but number of elements increases making miniaturization difficult
Solution Approach 1:
The patent combines the matching element and the second bandpass filter into a single integrated structure, reducing the total element count from four separate components to a more compact integrated design. This merging maintains the signal separation performance while significantly reducing device complexity.
Solution Approach 2:
The transmission line is designed to serve dual purposes: as a matching element for impedance transformation and as part of the second bandpass filter structure. This multi-functionality reduces the number of required elements while preserving the signal separation performance across different frequency bands.
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
Achieves miniaturization without degrading signal isolation or generating spurious signals, by reducing the number of elements in the diplexer and minimizing unwanted coupling between signal paths.
Implementation Method 1
a series resonant circuit connecting an input terminal and the second resonator. The series resonant circuit is composed of a capacitor provided between the input terminal and the second resonator, and an inductance component of a line that connects the input terminal and the second resonator via the capacitor
Data Source
AI summary
A diplexer includes a first bandpass filter provided between an input terminal and a first output terminal and selectively passing a signal in a first frequency band, and a second bandpass filter provided between the input terminal and a second output terminal and selectively passing a signal in a second frequency band. The first bandpass filter includes a plurality of first resonators. The second bandpass filter includes a second resonator and a series resonant circuit. The series resonant circuit is composed of a capacitor provided between the input terminal and the second resonator, and an inductance component of a line that connects the input terminal and the second resonator via the capacitor.