Compact Balance Filter with Electromagnetic Coupling
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Solution Overview
Problem
Conventional balanced-unbalanced conversion circuits for RF circuits in communication apparatuses suffer from high signal insertion loss and require a large number of components, leading to increased size and complexity.
Innovation Solution
A compact balance filter design with an unbalanced terminal and two pairs of balanced terminals, incorporating electromagnetic-field-coupled inductors and LC parallel resonators, which eliminates the need for a divider and reduces component count, allowing for miniaturization and low signal insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a divider and two balance filters are used for balanced-unbalanced conversion, then the conversion function is achieved, but the signal insertion loss increases and the device size increases
Solution Approach 1:
The patent combines the functions of a divider and multiple balance filters into a single integrated balance filter structure. The unbalanced terminal is directly connected to balanced terminals through integrated inductor and capacitor elements, eliminating the need for separate divider and filter components. This merging reduces the number of connection points and interfaces, thereby reducing signal insertion loss while maintaining the balanced-unbalanced conversion function.
2Reliability
If a divider and two balance filters are used for balanced-unbalanced conversion, then the conversion function is achieved, but the device complexity and mounting space increase
Solution Approach 1:
The patent integrates multiple functional elements (divider and balance filters) into a single monolithic structure with unbalanced and balanced terminals. The inductor and capacitor elements are formed as integrated components within the filter structure, eliminating the need for separate divider and filter components. This reduces device complexity and the number of mounting requirements.
3Reliability
If conventional balance filter design is used, then the conversion function is achieved, but the signal insertion loss is high
Solution Approach 1:
The patent employs a multilayer construction where inductor and capacitor elements are distributed across multiple layers. This three-dimensional arrangement optimizes the electromagnetic field distribution and reduces parasitic effects, leading to lower signal insertion loss. The layered structure allows for better control of signal paths and reduced interference between components.
4Reliability
If multiple separate components are used for balanced-unbalanced conversion, then the conversion function is achieved, but the mounting space increases
Solution Approach 1:
The patent consolidates the divider and balance filter functions into a single integrated component with a compact multilayer structure. The inductor and capacitor elements are formed within the same housing and substrate, eliminating the need for separate mounting of multiple components. This integration dramatically reduces the total mounting space required while maintaining all necessary conversion functions.
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 achieves low signal insertion loss and miniaturization by integrating multiple functions into a single balance filter, reducing the space and complexity required for communication apparatuses.
Implementation Method 1
The unbalanced-side inductor is electromagnetic-field-coupled to each of the first balanced-side inductor and the second balanced-side inductor
Implementation Method 2
a low pass filter is inserted between the unbalanced terminal and the unbalanced-side inductor, the low pass filter includes a first inductor, a first capacitor inserted between one end of the first inductor and the ground, and a second capacitor inserted between the other end of the first inductor and the ground
Data Source
Figure 1~2
Figure 3
Figure 4(A)~4(B)
AI summary
A small-sized balance filter including an unbalanced terminal and two pairs of balanced terminals and having a low signal insertion loss is provided. An unbalanced terminal UB, a first balanced terminal Tx including a first terminal Tx1 and a second terminal Tx2, and a second balanced terminal Rx including a first terminal Rx1 and a second terminal Rx2 are provided. An unbalanced-side inductor L2 is inserted between the unbalanced terminal UB and the ground, first balanced-side inductors L31, L32, and L33 are inserted between the first terminal Tx1 and the second terminal Tx of the first balanced terminal Tx, second balanced-side inductors L41, L42, and L43 are inserted between the first terminal Rx1 and the second terminal Rx2 of the second balanced terminal Rx, and the unbalanced-side inductor L2 is electromagnetic-field-coupled to each of the first balanced-side inductors L31, L32, and L33 and the second balanced-side inductors L41, L42, and L43.