Balanced Filter Circuit Without Grounded Resonance Capacitors
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Solution Overview
Problem
Existing balanced filter circuits, particularly those used in small-sized communication apparatuses, face challenges in downsizing due to the requirement for multiple conductor layers to support resonance capacitors connected to ground.
Innovation Solution
A balanced filter circuit design that includes a pair of balanced input and output ports, with first and second resonators magnetically and electrically coupled, and capacitors connected in parallel to these resonators but not to ground, allowing for a reduced number of conductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonance capacitors are connected to ground in a balanced LC filter, then the filter achieves proper resonance and filtering function, but the number of conductor layers increases
Solution Approach 1:
The patent extracts the ground connection requirement from the resonance capacitors, allowing them to function without being connected to ground. This removes the need for additional conductor layers while maintaining the filtering function through alternative circuit topology using series-connected resonators and capacitors.
Solution Approach 2:
Instead of connecting capacitors to ground as in conventional designs, the patent inverts the approach by connecting them in series between resonators without ground reference. This inverted topology achieves the same filtering effect with reduced layer complexity.
2Reliability
If multiple conductor layers are used to form resonance capacitors connected to ground, then the filter circuit functions properly, but the overall size of the filter increases
Solution Approach 1:
The ground connection requirement is extracted and removed from the capacitor design, enabling a more compact configuration that does not require multiple conductor layers, thus reducing the overall filter volume while maintaining proper circuit function.
Solution Approach 2:
The patent merges the functions of multiple conductor layers into a single-layer or reduced-layer configuration by using series-connected components that share common nodes, thereby achieving the same filtering performance in a more compact form factor.
3Reliability
If four resonance capacitors are used in a balanced LC filter, then the filter achieves balanced performance, but the number of components and conductor layers increases
Solution Approach 1:
The patent combines the functions of four separate resonance capacitors into a reduced configuration by using series connections where capacitors are shared between resonators. This merging reduces the total component count while maintaining balanced performance through symmetric circuit topology.
Solution Approach 2:
Each capacitor in the patent serves multiple functions simultaneously - acting as a resonance element for one resonator and a coupling element for adjacent resonators. This multi-functionality reduces the total number of components needed compared to conventional designs where each capacitor has a dedicated single function.
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 design enables the creation of a downsized balanced filter circuit and multilayered filter device, reducing the number of conductor layers and enhancing the filter's performance by maintaining the magnetic coupling between resonators.
Implementation Method 1
The first resonator and the second resonator are magnetically coupled to each other and electrically connected to each other
Data Source
AI summary
A filter circuit includes a pair of balanced input ports, a pair of balanced output ports, first and second resonators provided in parallel between the pair of balanced input ports and the pair of balanced output ports in a circuit configuration, a first capacitor connected in parallel to the first resonator, and a second capacitor connected in parallel to the second resonator. The first and second resonators are magnetically coupled to each other and electrically connected to each other. The first and second capacitors are not electrically connected to ground.