Variable Impedance Matching Circuit for Multi-Band Antenna
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Solution Overview
Problem
Compact portable devices with smaller antennas suffer from poor antenna performance and Over-The-Air (OTA) performance due to limited impedance tuning capabilities in traditional matching circuits, which restricts their operation across multiple frequency bands.
Innovation Solution
A matching circuit with a selecting circuit and tuning cells comprising tuning elements and control elements that adjust impedance by generating control signals to couple nodes to voltage levels, allowing the antenna to operate in multiple frequency bands by varying impedance between the antenna and RF circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If smaller antennas are used in compact portable devices, then device size is reduced, but antenna performance and OTA performance deteriorate
Solution Approach 1:
The patent compensates for the performance limitations of small antennas by dynamically changing the impedance parameters of the matching circuit. The control elements adjust the electrical characteristics to optimize the antenna's resonance and impedance matching across different frequency bands, thereby maintaining good OTA performance despite the reduced antenna size.
Solution Approach 2:
The matching circuit is designed with multi-functionality to support operation in multiple frequency bands (e.g., first frequency band and second frequency band). The control elements enable the circuit to adapt its impedance characteristics for different operating conditions, making the small antenna effective across various applications and frequency ranges.
2Device complexity
If fixed impedance matching circuits are used, then circuit simplicity is maintained, but multi-frequency band operation capability is limited
Solution Approach 1:
The patent introduces dynamic control elements that can switch between different impedance states based on control signals. This allows the matching circuit to adapt to different frequency bands while maintaining a relatively simple overall structure. The control elements are integrated into the existing circuit topology, adding functionality without significantly increasing complexity.
Data Source
AI summary
An electronic device for processing radio frequency signals includes an antenna, an RF circuit, and a matching circuit. The matching circuit provides variable impedance between the antenna and the RF circuit. The antenna is capable of operating in a first frequency band or a second frequency band according to the variable impedance The matching circuit includes a first element; a second element; a first tuning cell connected to the first element and the second element, and comprising a first tuning element, a second tuning element and a first control element, the first control element determining whether to make a first node connected between the first and second tuning elements couple to a voltage level according to a first control signal; and a selecting circuit coupled to the first control element and configured to generate the first control signal so as to adjust the variable impedance.