Ladder RF Filter Circuit With Parallel Inductors for Wider Bandwidth
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Solution Overview
Problem
The challenge of increasing bandwidth and reducing insertion loss in filter circuits is hindered by the limited ability to enhance the electromechanical coupling coefficient of resonators, which is constrained by material and processing technology.
Innovation Solution
A filter circuit design incorporating parallel resonant branches and series resonators connected in a ladder topology, with inductors connected in parallel to adjacent resonators, to increase the electromechanical coupling coefficient and improve bandwidth while reducing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electromechanical coupling coefficient of the resonator is increased to increase bandwidth and reduce insertion loss, then the bandwidth increases and insertion loss decreases, but it is difficult to greatly increase the electromechanical coupling coefficient due to limitations in material and processing technology
Solution Approach 1:
An inductor is introduced as an intermediary element connected in parallel to the resonator. This inductor forms an LC resonant circuit that couples with the mechanical resonance of the resonator, effectively increasing the electromechanical coupling coefficient without requiring changes to the resonator's material or structure. The inductor acts as a mediator that transforms electrical energy to enhance the coupling between electrical and mechanical domains.
Solution Approach 2:
The invention changes the electrical parameters of the filter circuit by adding the inductor, which modifies the resonant characteristics and coupling coefficient. By adjusting the inductance value and its connection configuration, the electromechanical coupling coefficient can be increased to meet bandwidth and insertion loss requirements without changing the physical parameters of the resonator itself.
2Device complexity
If conventional filter circuit design is used, then the structure is simple, but the bandwidth is limited and insertion loss is high due to insufficient electromechanical coupling coefficient
Solution Approach 1:
The inductor serves as an intermediary element that enhances the electromechanical coupling without fundamentally complicating the filter circuit structure. It is connected in parallel to existing resonators, forming an LC resonant circuit that improves coupling efficiency and thereby increases bandwidth while reducing insertion loss.
Solution Approach 2:
By changing the electrical parameters through the addition of the inductor, the filter circuit achieves improved bandwidth and reduced insertion loss. The parameter change is achieved by introducing a new component with specific inductance values that optimize the coupling coefficient without requiring complex structural modifications.
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 proposed design enhances the electromechanical coupling coefficient, thereby increasing bandwidth and reducing insertion loss in filter circuits, improving filtering performance and reducing production costs.
Implementation Method 1
The first inductor is connected in parallel to at least two adjacent series resonators in the plurality of series resonators... to increase an electromechanical coupling coefficient of the series resonant branch
Implementation Method 2
The first inductor may be connected in parallel to at least one parallel resonator in any one of the plurality of parallel resonant branches... to increase an electromechanical coupling coefficient of the parallel resonant branch
Implementation Method 3
A filter circuit including a resonator may filter a radio frequency signal... The plurality of parallel resonant branches and the plurality of series resonators may be disposed based on a ladder topology
Data Source
AI summary
A filter circuit includes a plurality of parallel resonant branches, a plurality of series resonators, and a first inductor. The plurality of parallel resonant branches and the plurality of series resonators are disposed based on a ladder topology. Each parallel resonant branch includes at least one parallel resonator. The first inductor is connected in parallel to at least two adjacent series resonators in the plurality of series resonators, or is connected in parallel to at least one parallel resonator in any parallel resonant branch.