RF Filter Circuit With FSL Notch Tuning Signal Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current tunable notch filter banks in RF receive systems are power-consuming, slow to respond, and require complex feedback loops to suppress interfering signals, while frequency selective limiters (FSLs) lack efficient methods to remove tuning signals from the output.
Innovation Solution
An RF filter system utilizing first and second frequency selective limiters (FSLs) with tuning signal injection and cancellation circuitry, including hybrid couplers, to generate notches in the transmission response and remove unwanted signals without passing tuning signals down the receive chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current tunable notch filter banks are used to suppress interfering signals, then signal filtering capability is improved, but power consumption increases and response speed decreases
Solution Approach 1:
The FSL automatically adjusts its transmission response based on the input spectrum without requiring external control signals or feedback loops. The device self-regulates by detecting high-power signals and dynamically generating notches, eliminating the need for power-consuming sense-and-control feedback loops while maintaining effective interference suppression
Solution Approach 2:
The FSL dynamically changes its transmission characteristics (creating notches) in response to detected high-power signals. This parameter change allows the device to adapt to varying interference conditions without requiring external tuning commands, thereby reducing power consumption while maintaining filtering effectiveness
2Reliability
If current tunable notch filter banks are used to suppress interfering signals, then signal filtering capability is improved, but response speed decreases
Solution Approach 1:
The FSL immediately responds to high-power signals by automatically generating notches in its transmission response. This self-service mechanism eliminates the delay associated with feedback loops and external control signal processing, enabling rapid adaptation to changing interference conditions while maintaining effective signal filtering
Solution Approach 2:
The FSL is pre-configured to immediately attenuate any high-power signal it detects without requiring preliminary control commands. This preliminary readiness allows the device to respond instantaneously to interfering signals, achieving fast response speed while maintaining filtering capability
3Adaptability or versatility
If multiple FSLs are used to provide multiple notches, then filtering versatility is improved, but device complexity increases
Solution Approach 1:
Each FSL is designed to be universally applicable across a wide frequency range and can dynamically generate multiple notches based on the input spectrum. This multi-functionality allows a single FSL to replace multiple fixed-frequency filters, achieving filtering versatility without increasing device complexity
Solution Approach 2:
The FSL dynamically adapts its transmission response to provide the necessary number and position of notches based on the detected interfering signals. This dynamic behavior allows the device to provide filtering versatility on-demand, eliminating the need for multiple static filter devices and reducing overall system complexity
4Reliability
If tuning signals are injected to generate notches in FSL transmission response, then filtering capability is improved, but tuning signals appear in the output
Solution Approach 1:
The system extracts and removes the tuning signals from the output path after they have served their purpose of generating notches in the FSL transmission response. This extraction process eliminates the harmful effect of tuning signals appearing in the final output while preserving the filtering capability they enabled
Solution Approach 2:
The tuning signals serve as an intermediary mechanism to control the FSL's transmission response without being present in the final output. By using the tuning signals only as a control intermediary and then removing them, the system achieves filtering capability without contaminating the output with unwanted tuning signals
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 system efficiently suppresses high-power interfering signals while allowing lower-power signals to pass, dynamically adapting to the input spectrum with minimal power consumption and rapid response, and removes tuning signals from the output.
Implementation Method 1
A frequency selective limiter (FSL) is a nonlinear passive device that attenuates RF signals provided to an input thereof having a power level which is above a predetermined threshold power level. RF signals having a power level below the predetermined threshold power level, on the other hand, propagate from the input of the FSL to the output of the FSL substantially unattenuated.
Implementation Method 2
The FSL's transmission response can automatically and dynamically adjust to the input spectrum based on power spectral density and can automatically generate notches in the transmission response proportional to a signal's supercriticality (e.g., how far a signal's power is above a designated power threshold level).
Data Source
AI summary
Embodiments of the present disclosure relate to RF filter systems and methods. In some embodiments, an RF filter system includes a tuning signal injection circuitry, a tuning signal cancellation circuitry, and two FSLs. The RF filter system may receive one or more first RF signals that may include one or more signals of interest (SOIs) and one or more interfering signals. The RF filter system may receive one or more second RF signals that may include one or more tuning signals. The RF filter system may output one or more RF signals containing the one or more SOIs and attenuated versions of the interfering signals, without including the one or more tuning signals.