RF Module Switch Circuit for Carrier Aggregation Isolation
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Solution Overview
Problem
Radio frequency modules face a decrease in reception sensitivity when downsizing, particularly when a transmit band of one communication band includes a receive band of another, due to signal leakage through switch circuits during carrier aggregation.
Innovation Solution
The radio frequency module employs a switch circuit with specific terminal connections and switch configurations to isolate signals, allowing the use of a single transmit amplifier for multiple bands while preventing signal leakage, and using a transmit filter as a receive filter for overlapping bands to reduce module size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a transmit filter of the second communication band is used as a receive filter of the first communication band, then the radio frequency module size is reduced, but signal leakage occurs from the transmit amplifier to the receive amplifier through the switch circuit
Solution Approach 1:
The switch circuit is divided into multiple independent switches (first switch, second switch, third switch) that can be controlled separately. This segmentation allows selective connection/disconnection of signal paths to prevent leakage while maintaining filter sharing for size reduction.
Solution Approach 2:
The switch circuit acts as an intermediary between the transmit amplifier and the shared filter, and between the receive amplifier and the shared filter. By controlling the switch states, it mediates signal flow to prevent direct leakage paths while enabling filter sharing functionality.
2Reliability
If dedicated filters are installed for each communication band, then reception sensitivity is maintained, but the radio frequency module size increases
Solution Approach 1:
The transmit filter of the second communication band is designed to serve dual purposes: as a transmit filter for the second band and as a receive filter for the first band. This multi-functionality reduces the total number of filters needed while maintaining performance through proper switch control.
Solution Approach 2:
The patent merges the functionality of separate transmit and receive filters by allowing the second band transmit filter to handle both transmit for band 2 and receive for band 1, reducing component count and module size while maintaining signal integrity through switch isolation.
3Productivity
If carrier aggregation is performed using multiple communication bands, then communication throughput is increased, but signal leakage between bands occurs through the switch circuit
Solution Approach 1:
The switch circuit provides dynamic control over signal paths, allowing the system to adaptively connect or disconnect specific bands for transmit and receive operations. This dynamic switching enables carrier aggregation while preventing harmful signal leakage between aggregated bands through independent switch control.
Data Source
AI summary
A radio frequency module includes a transmit filter of Band A and Band B, a transmit amplifier, and a switch circuit and can perform CA using a transmit signal of Band A and a receive signal of Band B, a transmit band of Band B including a receive band of Band C. The switch circuit includes a switch switching connection between a common terminal and a first selection terminal, a switch switching connection between the common terminal and a second selection terminal, and a switch switching connection between the second selection terminal and a third selection terminal. The common terminal is connected to the transmit amplifier. The first selection terminal is connected to the transmit filter of Band A. The second selection terminal is connected to the transmit filter of Band B. The third selection terminal is connected to a receive path of Band C.