Tunable RF Balun Reactance for Multi-Band Frequency Support
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Solution Overview
Problem
Conventional LC balun topologies are narrowband and require different discrete baluns for different RF frequencies, limiting their ability to support multiple frequencies simultaneously, such as 433MHz, 868MHz, and 916MHz, which are essential for applications like asset tracking and sensor systems.
Innovation Solution
A system and method that dynamically changes impedance by using tunable reactive elements, such as barium strontium titanate capacitors and switched capacitor/inductor banks, within the RF circuit to support multiple frequencies, allowing for real-time or near real-time switching between different frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional LC balun topologies are used, then the circuit is simple and reliable, but it can only support a single narrow frequency band
Solution Approach 1:
The patent applies dynamics by making the reactance of the balun circuit variable rather than fixed. A controller dynamically adjusts the reactance value based on the operating frequency, enabling the same circuit to adapt to multiple frequency bands (e.g., 433MHz, 868MHz, 916MHz) while maintaining proper impedance matching and signal integrity across different frequencies.
Solution Approach 2:
The patent changes the parameter of reactance from a fixed value to a variable value that can be adjusted according to the operating frequency. By controlling the reactance parameter dynamically, the balun circuit achieves broadband frequency support without requiring multiple discrete circuits, thus resolving the contradiction between versatility and complexity.
2Reliability
If different discrete baluns are used for different frequencies, then each frequency is optimized, but the device complexity and component count increase
Solution Approach 1:
The patent implements universality by designing a single balun circuit that can perform the function of multiple frequency-specific baluns. Through dynamic reactance adjustment controlled by a controller, one circuit achieves what previously required multiple discrete components, reducing device complexity while maintaining reliable performance across different frequencies.
Solution Approach 2:
The patent merges multiple frequency-specific balun functions into a single unified circuit structure. By combining the frequency selection logic and reactance adjustment mechanisms into one integrated system, the patent eliminates the need for separate discrete baluns for each frequency, thereby reducing component count while preserving frequency-optimized performance.
3Adaptability or versatility
If fixed reactance is used, then the circuit is stable and simple, but it cannot support multiple RF frequencies simultaneously
Solution Approach 1:
The patent employs feedback mechanisms where a controller monitors the operating frequency and automatically adjusts the reactance value to maintain optimal impedance matching. This closed-loop control ensures that the balun circuit remains properly matched across different frequency bands, making the system easy to operate across multiple frequencies without manual intervention.
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
Enables simultaneous support of multiple RF frequencies, including 433MHz, 868MHz, and 916MHz, facilitating applications like asset tracking, cargo detection, and sensor systems, while meeting regulatory requirements, and optimizing signal transmission across various frequency bands.
Implementation Method 1
dynamically change reactance (e.g., capacitance and/or inductance) to support multiple RF frequencies
Implementation Method 2
dynamically change reactance (e.g., capacitance and/or inductance) to support multiple RF frequencies
Implementation Method 3
the low pass filter outputs a first part of the first portion of the signal that is below a first frequency cutoff
Data Source
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AI summary
A method is disclosed that includes, for example, a method comprising receiving from a transceiver that is implemented as an integrated circuit (IC) chip, by a variable reactive element, a signal, wherein the signal is in a frequency band that comprises a first sub-frequency band and a second sub-frequency band, controlling, by a controller, the variable reactive element, such that the variable reactive element is placed into one of a group of states, wherein the group of states comprises a first state having a first reactance and a second state having a second reactance, and wherein the first reactance is different from the second reactance and providing a low pass filter coupled to the variable reactive element, wherein the low pass filter receives from the variable reactive element the first portion of the signal in a first case that the variable reactive element is placed into the first state, wherein the low pass filter receives from the variable reactive element the second portion of the signal in a second case that the variable reactive element is placed into the second state, wherein in the first case the low pass filter outputs a first part of the first portion of the signal that is below a first frequency cutoff, wherein in the second case the low pass filter outputs a second part of the second portion of the signal that is below a second frequency cutoff, and wherein the first frequency cutoff is below the second frequency cutoff.