Ladder RF Filter Topology Using Parallel Inductors to Cut Insertion Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge lies in increasing the bandwidth and reducing the insertion loss of radio frequency filter circuits, which is limited by the difficulty in enhancing the electromechanical coupling coefficient of resonators due to material and processing constraints.
Innovation Solution
A filter circuit design incorporating parallel and series resonant branches with inductors connected in parallel to adjacent resonators, forming a ladder topology to increase the equivalent electromechanical coupling coefficient, thereby enhancing bandwidth and 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 material and processing technology limitations
Solution Approach 1:
The patent combines multiple resonators (series resonators and parallel resonators) into a unified filter circuit structure where they work together to achieve the desired bandwidth and insertion loss performance. By merging the functions of multiple resonators with different coupling coefficients, the system overcomes the limitation of individual resonators having insufficient electromechanical coupling coefficients.
Solution Approach 2:
The patent changes the configuration parameters of the filter circuit by introducing both series resonators and parallel resonators with different electromechanical coupling coefficients. By adjusting the number, arrangement, and electrical connections of these resonators, the overall system achieves high bandwidth and low insertion loss without requiring individual resonators to have extremely high coupling coefficients that are difficult to manufacture.
2Reliability
If more resonators are added to increase the electromechanical coupling coefficient, then the bandwidth and insertion loss improve, but the device complexity increases
Solution Approach 1:
The patent segments the filter circuit into distinct series resonant branches and parallel resonant branches, each containing specific resonators with defined electromechanical coupling coefficients. This segmentation allows for modular design and optimization, where each segment contributes specifically to the overall bandwidth and insertion loss performance without requiring the entire circuit to be overly complex.
Solution Approach 2:
The patent designs the filter circuit so that the same basic resonator structure serves multiple functions depending on its configuration (series or parallel connection). The resonators universally provide frequency-selective filtering functionality while their arrangement determines the specific electromechanical coupling effect, reducing the need for completely different component types and simplifying the overall device complexity.
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 effectively increases the electromechanical coupling coefficient, leading to improved bandwidth and reduced insertion loss in radio frequency filter circuits.
Implementation Method 1
A filter circuit including a resonator may filter a radio frequency signal
Implementation Method 2
The first inductor is connected in parallel to at least two adjacent series resonators in the plurality of series resonators
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
This application provides a filter circuit, a radio frequency front-end circuit, a radio frequency chip, and an electronic device, to increase an equivalent electromechanical coupling coefficient of the filter circuit. This further increases bandwidth of the filter circuit, and reduces an insertion loss of the filter circuit. The filter circuit may include 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 may be disposed based on a ladder topology. Each parallel resonant branch may include at least one parallel resonator. The first inductor may be connected in parallel to at least two adjacent series resonators in the plurality of series resonators, or may be connected in parallel to at least one parallel resonator in any parallel resonant branch.