Tunable RF Filter With Coupled Inductors and Switched Notch Control
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Solution Overview
Problem
Current RF communication systems face challenges in achieving strong harmonic rejection, particularly with the integration of multiple bands in 5G New Radio (NR) technology, where filters require increased tunability to meet harmonic specifications, leading to high costs and complexity due to the large number of switches needed.
Innovation Solution
The implementation of tunable filters with mutually coupled inductors and a tunable impedance circuit, utilizing switches to adjust capacitance and achieve harmonic rejection for multiple harmonics, reduces the number of switches required and enhances tunability, allowing for M×2N harmonic states with fewer switches compared to previous designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional filters are used to achieve harmonic rejection in multi-band RF systems, then filtering performance is maintained, but the number of switches required increases significantly, leading to high cost and device complexity
Solution Approach 1:
The patent combines multiple filter functions into a single tunable filter structure with mutually coupled inductors. By merging the functionality of multiple traditional filters into one integrated structure that can be tuned to different bands, the design achieves harmonic rejection across multiple bands without requiring separate switches for each band, thereby reducing the total number of switches while maintaining filtering performance
Solution Approach 2:
The patent implements dynamic tunability in the filter structure, allowing the filter to adapt its characteristics to different frequency bands. This dynamic capability enables a single filter structure to replace multiple static filters, reducing the need for multiple switches while maintaining the ability to achieve harmonic rejection across various bands through electronic tuning
2Adaptability or versatility
If multiple switches are added to achieve tunability for multiple harmonics, then harmonic rejection capability is improved, but the die area and cost of switch implementation increase
Solution Approach 1:
The patent designs a universal tunable filter structure that can handle multiple harmonics and frequency bands with a single implementation. The mutually coupled inductor configuration provides multi-functionality, allowing the same structure to reject second, third, and fourth harmonics across different bands without requiring separate switch implementations for each harmonic, thereby reducing die area while maintaining adaptability
Solution Approach 2:
The patent achieves tunability for multiple harmonics by changing the electrical parameters (capacitance values) of the filter circuit rather than adding multiple physical switches. By varying the capacitance values in the tunable impedance circuit, the filter can be tuned to reject different harmonics and frequency bands, providing versatility without increasing die area through additional switch 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 cost and die area of switch implementations while providing effective harmonic rejection for a larger number of harmonics, improving the ability to filter harmonics such as second, third, and fourth harmonics concurrently, and can be applied to various communication technologies including 5G NR.
Implementation Method 1
a second inductor mutually coupled with the first inductor
Implementation Method 2
The tunable impedance circuit includes a switch and is configured to adjust at least two notches in a frequency response of the tunable filter by changing a state of the switch
Data Source
AI summary
Aspects of this disclosure relate to a tunable filter with tunable rejection. The tunable filter includes mutually coupled inductors and a tunable impedance circuit electrically connected to at least one of the mutually coupled inductors. The tunable impedance circuit is configured to adjust at least two notches in a frequency response of the tunable filter by changing a state of a switch. The tunable filter can filter a radio frequency signal. Related methods, radio frequency systems, radio frequency modules, and wireless communication devices are also disclosed.