Half-Lattice RF Filter With Phase Shifter for Wider Bandwidth
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Solution Overview
Problem
Current RF filters, particularly in mobile communication systems, face challenges in achieving increased bandwidth while maintaining high out-of-band suppression, steep skirts, and low insertion loss, especially with the upcoming 5G requirements that demand bandwidths three to four times larger than those for LTE bands.
Innovation Solution
A half lattice filter topology is introduced, featuring a signal path with a first segment and a parallel branch, where a first electro-acoustic resonator and an impedance element are connected in series, along with a phase shifter comprising inductively coupled inductance elements, which allows for a reduced number of circuit elements and increased bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a ladder-type filter topology is used, then high isolation levels and steep filter skirts are achieved, but the bandwidth is limited by the electro acoustic coupling coefficient
Solution Approach 1:
The filter is divided into multiple resonator stages (first resonator, second resonator, third resonator) with distinct functions. The first resonator provides input coupling, the second resonator provides output coupling, and the third resonator provides feedback coupling. This segmentation allows each resonator to be optimized for its specific function, enabling bandwidth expansion while maintaining filter skirt steepness through the distributed resonance structures.
Solution Approach 2:
The patent introduces a feedback path from the output of the second resonator back to the input of the first resonator through the third resonator. This dynamic feedback mechanism allows the filter to adapt its frequency response characteristics, enabling bandwidth expansion while maintaining the steep roll-off characteristics through controlled energy redistribution across the resonators.
2Adaptability or versatility
If the bandwidth is increased for 5G requirements, then future communication standards are supported, but other filter parameters such as out of band suppression and insertion loss may deteriorate
Solution Approach 1:
Different resonators are assigned different local qualities and functions: the first resonator is optimized for input coupling with specific Q-factor characteristics, the second resonator for output coupling, and the third resonator for feedback coupling. This local optimization allows the overall filter to achieve wide bandwidth while maintaining high out-of-band suppression through the coordinated performance of each locally-optimized resonator stage.
Solution Approach 2:
The third resonator provides a feedback path that samples the output signal and feeds it back to the input stage. This feedback mechanism enables the filter to maintain high out-of-band suppression by actively canceling unwanted frequency components while allowing the passband to extend to wider bandwidths required for 5G applications.
3Adaptability or versatility
If the bandwidth is increased for 5G requirements, then future communication standards are supported, but insertion loss within the passband may increase
Solution Approach 1:
The dynamic feedback configuration allows energy to be redistributed across the resonator network. By controlling the feedback coupling through the third resonator, the system can maintain low insertion loss in the passband while achieving wide bandwidth, as the feedback path compensates for energy losses through constructive interference within the optimized frequency range.
Solution Approach 2:
The patent optimizes specific parameters including the Q-factors of individual resonators, the coupling coefficients between resonators, and the feedback coupling strength. By carefully adjusting these parameters, the filter achieves wide bandwidth with minimal insertion loss, as the optimized parameter combinations enable efficient energy transfer across the expanded frequency range while minimizing dissipative losses.
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 half lattice filter achieves a substantially increased bandwidth while maintaining high out-of-band suppression, steep skirts, and good impedance matching, effectively addressing the bandwidth requirements for future communication standards.
Implementation Method 1
The phase shifter comprises two inductively coupled inductance elements
Implementation Method 2
electro acoustic resonators that allow for high isolation levels and steep filter skirts
Data Source
AI summary
An RF filter (BPF) with an increased bandwidth is provided. The filter comprises a half-lattice topology and a phase shifter (PS) comprising inductively coupled inductance elements in a parallel branch parallel to a first segment (S1) of a signal path (SP) between a first port (P1) and a second port (P2) of the filter.