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
A radio frequency module configuration with specific switch circuits and filters allows for simultaneous transmission and reception across multiple communication bands, including a scenario where a transmit band of one band includes a receive band of another, by using a multi-connection type switch circuit with strategically placed switches to prevent signal leakage and improve isolation.
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 for downsizing, then the number of filters is reduced and device size is decreased, but signal leakage occurs from the transmit amplifier to the receive amplifier through the switch circuit, causing reception sensitivity to deteriorate
Solution Approach 1:
The switch circuit is segmented into multiple switches (first switch, second switch, third switch) arranged in a specific configuration. This segmentation allows the circuit to provide both downsizing benefits and adequate signal isolation by creating multiple switching paths that can be independently controlled to prevent signal leakage while sharing filter components.
2Reliability
If multiple filters are installed for different communication bands to ensure proper signal filtering, then reception sensitivity is maintained, but the device size increases and downsizing cannot be achieved
Solution Approach 1:
The same filter component serves multiple functions: it acts as a transmit filter for the second communication band and simultaneously serves as a receive filter for the first communication band. This multi-functionality reduces the total number of filters needed while maintaining proper signal filtering performance through the carefully designed switch circuit configuration.
3Device complexity
If a simple switch circuit configuration is used to achieve downsizing, then device complexity is reduced, but signal isolation between transmit and receive paths deteriorates, causing transmit signal leakage into the receive amplifier
Solution Approach 1:
The switch circuit acts as an intermediary between the transmit amplifier and the filter/share point, and between the receive amplifier and the filter/share point. The multiple switches create intermediary connection points that enable proper signal routing and isolation, preventing direct signal leakage paths while maintaining a relatively simple overall circuit structure.
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.