RF Front-End Filter Switching With Phase Alignment Across Bands
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radio-frequency front-end circuits face degradation in communication quality due to excessive attenuation in reception and mismatched impedance for simultaneous use of multiple frequency bands, particularly when switching between transmission and reception signals in different frequency bands.
Innovation Solution
A radio-frequency front-end circuit design incorporating separate transmit and receive filters, a switch, and a phase adjusting circuit to manage signal paths for TDD and FDD communications, ensuring optimal impedance matching and phase alignment across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same filter is used for both transmission and reception in the same frequency band, then the device complexity is reduced, but the reception quality degrades due to excessive attenuation determined for transmission
Solution Approach 1:
The patent divides the filter system into separate transmit and receive filters, each optimized for their specific function. The transmit filter is designed with high attenuation characteristics suitable for transmission, while the receive filter is designed with lower attenuation to preserve weak received signals, thereby resolving the contradiction between device simplicity and reception quality.
Solution Approach 2:
The patent applies different filter characteristics to different signal paths based on local requirements. The transmit path uses a filter with high attenuation properties, while the receive path uses a filter with low attenuation properties, allowing each path to have the optimal filter characteristics for its specific function.
2Reliability
If separate transmit and receive filters are used, then the reception quality is improved, but the device complexity increases
Solution Approach 1:
The patent employs a single switch component that handles multiple functions: selecting between transmit and receive filters, managing TDD and FDD signal paths, and coordinating phase adjustment. This multi-functional approach allows separate optimized filters to be used without proportionally increasing overall device complexity.
3Adaptability or versatility
If a switch is used to connect the antenna to different filters for TDD and FDD, then the adaptability for multiple frequency bands is improved, but the phase alignment degrades causing EVM degradation
Solution Approach 1:
The patent introduces a phase adjusting circuit as an intermediary component between the switch and the signal processing chain. This circuit actively compensates for phase changes introduced by switching operations, thereby maintaining phase alignment and preventing EVM degradation while preserving the ability to support multiple frequency bands.
Solution Approach 2:
The phase adjusting circuit operates by detecting phase deviations caused by switching and applying corrective phase adjustments in real-time. This feedback mechanism ensures that phase alignment is maintained despite the use of switches for multi-frequency band adaptability.
Data Source
AI summary
In simultaneous communication using multiple frequency bands, the degradation in the communication quality is suppressed. The radio-frequency front-end circuit (1) includes an antenna terminal (2), a transmit filter (3), a receive filter, a transport filter, a switch (6), and a phase adjusting circuit (7). The switch (6) is capable of connecting the antenna terminal (2) to the transmit filter (3) or the receive filter and the transport filter simultaneously. The transmit filter (3) is disposed on a transmission path (T1). The receive filter is disposed on a reception path. The transport filter is disposed on a transport path. The phase adjusting circuit (7) is disposed on at least one of paths, the transmission path (T1), the reception path, and a reception/transmission path.