RF Front-End Tunable Notch Filters for Harmonic Rejection
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Solution Overview
Problem
Current radio frequency (RF) communication systems face challenges in meeting harmonic rejection specifications, particularly with the integration of multiple bands in 5G New Radio (NR) technology, where filters require increased tunability to manage concurrent signals effectively, leading to high costs and complexity due to the need for numerous switches.
Innovation Solution
The implementation of tunable filters with mutually coupled inductors and a tunable impedance circuit, which uses switches to selectively couple capacitors, allowing for M×2N harmonic states, where M is greater than 2, reducing the number of switches required and lowering costs while enhancing harmonic tunability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filters with strong harmonic rejection are implemented in RF communication systems, then harmonic rejection capability is improved, but device complexity and cost increase due to the need for numerous switches to achieve increased tunability
Solution Approach 1:
The patent combines multiple filter functions into a single tunable filter structure that can simultaneously or sequentially provide harmonic rejection for multiple frequency bands. The tunable filter integrates multiple resonant circuits with different Q-factors, allowing one filter component to perform what previously required multiple separate filters and switches.
Solution Approach 2:
The patent implements dynamic tunability in the filter structure, allowing the resonant frequencies and Q-factors to be adjusted based on the operating band. This dynamic adjustment capability enables the filter to adapt to different frequency requirements without requiring separate fixed filters for each band, reducing the overall number of components needed.
2Adaptability or versatility
If multiple bands are integrated in 5G New Radio technology, then adaptability and versatility are improved, but device complexity increases due to the need for numerous switches to manage concurrent signals
Solution Approach 1:
The patent designs a universal tunable filter structure that can serve multiple frequency bands and functions. The filter incorporates adjustable resonant circuits that can be configured to support different 5G NR bands, allowing a single filter component to replace what would traditionally require multiple band-specific filters and complex switching networks.
Solution Approach 2:
The patent utilizes parameter adjustment mechanisms that allow the filter's resonant frequency and bandwidth to be changed based on the desired operating band. By varying the electrical parameters (capacitance, inductance) of the resonant circuits, the filter can be tuned to support different 5G NR frequency ranges without requiring physical reconfiguration or additional switches.
3Device complexity
If the number of switches is reduced in the RF system, then device complexity and cost decrease, but achieving the same harmonic rejection and multi-band support becomes more challenging
Solution Approach 1:
The patent segments the filter into multiple resonant circuit modules, each with specific Q-factor characteristics. By carefully designing the segmentation and interconnection of these modules, the filter achieves cumulative harmonic rejection performance without requiring additional switches. Each segment contributes to rejecting specific harmonic frequencies, and their combined effect provides comprehensive harmonic suppression.
Solution Approach 2:
The patent employs a composite filter structure combining resonant circuits with different Q-factors and frequency characteristics. This composite approach allows the filter to leverage the strengths of each component circuit, achieving high harmonic rejection across multiple bands through the synergistic interaction of the composite structure rather than through additional switching components.
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 solution reduces the number of switches needed, decreases die area and cost, and effectively filters harmonics such as the second, third, fourth, and fifth harmonics, while providing strong harmonic rejection and notch filtering capabilities, improving the efficiency and cost-effectiveness of RF communication systems.
Implementation Method 1
tunable filters with mutually coupled inductors
Implementation Method 2
tunable impedance circuit
Implementation Method 3
effectively filters harmonics such as the second, third, fourth, and fifth harmonics
Data Source
AI summary
Aspects of this disclosure relate to a radio frequency system with tunable notch filtering. The radio frequency system includes a first tunable filter and a second tunable filter. The first tunable filter is coupled between an output of a power amplifier and a radio frequency switch. The second tunable filter is coupled between an antenna switch and an antenna node. The second tunable filter has a notch at a lower frequency than a notch of the first tunable filter. Related methods and wireless communication devices are also disclosed.