RF Circuit Dynamic Impedance Tuning for FDD TDD Duplexing
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Solution Overview
Problem
Current radio frequency circuits for FDD systems have limited band range and are inflexible, requiring multiple duplexers for multiple bands, increasing cost and complexity, and are incompatible with TDD systems, which further complicates the design and increases costs.
Innovation Solution
A radio frequency circuit with a controller and duplexing modules that include impedance tuners and circulators, allowing for dynamic impedance matching and decoupling of duplexing and filtering functions, enabling broadband operation and compatibility with both TDD and FDD modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple groups of duplexers are used to support multiple modes and bands, then the supported band range increases, but the cost, area, and complexity of the radio frequency circuit increase
Solution Approach 1:
The patent applies a single duplexer design that can support multiple communication modes (FDD and TDD) and multiple frequency bands through dynamic impedance tuning. The impedance tuner adjusts the impedance of the antenna port to match different band requirements, allowing one duplexer to perform the functions that would traditionally require multiple separate duplexers. This multi-functional approach reduces the number of components while maintaining broad adaptability across different bands and modes.
Solution Approach 2:
The patent introduces a controller that dynamically adjusts the impedance of the antenna port based on the operating mode and frequency band. By making the impedance tunable rather than fixed, the system can adapt to different communication standards (FDD/TDD) and frequency ranges without requiring hardware changes. This dynamic adjustment capability enables a single duplexer to cover multiple bands that would otherwise require separate fixed-band duplexers.
2Adaptability or versatility
If a TR switch is added to support TDD system, then TDD compatibility is achieved, but the cost, area, and complexity of the radio frequency circuit increase
Solution Approach 1:
The patent designs the duplexer with inherent support for both FDD and TDD modes by implementing dynamic impedance tuning capability. The same duplexer structure can operate in frequency-division duplexing mode or time-division duplexing mode by adjusting the impedance of the antenna port through the controller. This eliminates the need for separate TDD-specific components like TR switches, as the duplexer itself becomes universal across both duplexing methodologies.
Solution Approach 2:
The patent merges the functions of FDD and TDD support into a single duplexer design. Rather than having separate duplexers or adding a TR switch to an existing FDD duplexer, the invention integrates both mode capabilities directly into the duplexer's impedance tuning mechanism. The controller manages the impedance adjustments to accommodate both FDD and TDD operational requirements within the same hardware architecture.
3Reliability
If resonance filters are used for TX-RX separation, then filtering function is provided, but the working band is narrow and fixed
Solution Approach 1:
The patent replaces fixed-band resonance filters with a dynamic impedance tuning system. The controller adjusts the impedance of the antenna port in real-time to maintain optimal filtering performance across different frequency bands and operating modes. This dynamic adjustment allows the filtering function to adapt to various bands without being constrained by the fixed resonant frequencies of traditional SAW/BAW filters.
Solution Approach 2:
The patent changes the impedance parameter of the antenna port through the impedance tuner to adapt to different operating conditions. By varying the impedance value based on the selected frequency band and duplexing mode, the system maintains effective TX-RX separation and filtering performance across a wide range of frequencies. This parameter adjustment approach replaces the fixed-frequency resonance characteristic with a tunable impedance characteristic.
Data Source
AI summary
A radio frequency circuit. In the circuit, a first directional coupler receives a second transmit signal, uses a part of the second transmit signal as a third transmit signal, directly sends the third transmit signal to a first port of a circulator, and obtains a first coupling signal from the second transmit signal; the circulator outputs the third transmit signal through a second port; an impedance tuner transmits the third transmit signal to an antenna port and transmits, to the second port of the circulator, a first input signal from the antenna port; the circulator inputs the first input signal to a second directional coupler through a third port; the second directional coupler obtains a second coupling signal from the first input signal; and a controller adjusts impedance of the impedance tuner according to the first coupling signal and the second coupling signal.