RF Circuit Switching for Intermodulation Distortion Control
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Solution Overview
Problem
Simultaneous transmission of radio-frequency signals with different frequencies in multiband/multimode-compatible radio-frequency front-end modules leads to intermodulation distortion and deteriorated reception sensitivity due to harmonic interference.
Innovation Solution
A radio-frequency circuit with transfer circuits for different frequency bands and a switch circuit that connects antennas based on the frequency of intermodulation distortion, ensuring that transfer circuits with interfering frequencies are isolated or connected to the same antenna to minimize distortion and sensitivity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If simultaneous transmission of first radio-frequency transmission signal and second radio-frequency transmission signal is performed, then multiband/multimode compatibility is achieved, but intermodulation distortion is generated and radio-frequency signal quality deteriorates
Solution Approach 1:
The patent divides the transmission paths into separate segments by introducing first and second band selector switches that can independently select different frequency bands. This segmentation allows the system to maintain multiband compatibility while preventing intermodulation distortion by isolating conflicting frequency paths.
Solution Approach 2:
The patent employs dynamic switching mechanisms where the band selector switches can change their connection states based on the frequency bands being used. This dynamic reconfiguration enables the system to adapt to different transmission scenarios, connecting transmission paths appropriately to avoid intermodulation distortion while maintaining multiband functionality.
2Adaptability or versatility
If frequency of second harmonic of first radio-frequency transmission signal or second radio-frequency transmission signal is included in frequency band of reception circuit, then harmonic interference occurs, but reception sensitivity deteriorates
Solution Approach 1:
The patent introduces band selector switches as intermediary elements between the transmission paths and antennas. These switches act as mediators that can isolate transmission paths when their second harmonics would interfere with reception circuits, thereby preventing harmonic interference while maintaining frequency band coverage capability.
Solution Approach 2:
The patent implements preliminary anti-action by proactively controlling the band selector switches to prevent harmonic interference before it occurs. The switches are configured to isolate transmission paths in advance when frequency combinations that would generate harmful second harmonics are detected, thus protecting reception sensitivity before deterioration can occur.
Data Source
AI summary
A radio-frequency circuit includes: a first transfer circuit that outputs a B1 or B3 first transmission signal amplified by a first power amplifier from a first input/output terminal; a second transfer circuit that outputs an n77 or n79 second transmission signal amplified by a second power amplifier from a second input/output terminal; and a switch. When a B1 first transmission signal and an n77 second transmission signal are simultaneously transmitted, the switch connects the first transfer circuit to a first antenna and connects the second transfer circuit to a second antenna since intermodulation distortion IMD2 overlaps with B1. When a B3 first transmission signal and an n79 second transmission signal are simultaneously transmitted, the switch connects both of the first transfer circuit and the second transfer circuit to the first antenna since intermodulation distortion IMD2 does not overlap with B3.