High-frequency front-end circuit signal leakage suppression
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Solution Overview
Problem
High-frequency front-end circuits with switches experience signal leakage between communication bands due to overlapping frequency bands, leading to degraded reception sensitivity when transmitting and receiving signals in bands that are close or overlapped.
Innovation Solution
Incorporating a band switch and main switch with additional selection terminals and a load circuit or duplexer to suppress signal leakage by routing leakage signals to ground or a different communication band, and optimizing duplexer placement on a circuit board to increase signal path distance and reduce electromagnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switch-based high-frequency front-end circuit is used to demultiplex signals in multiple communication bands, then the circuit can route signals between different bands, but signal leakage occurs between closely spaced or overlapping bands, degrading reception sensitivity
Solution Approach 1:
A third selection terminal is introduced as an intermediary between the first and second selection terminals. This intermediary terminal provides an additional signal path that enables better isolation between closely spaced communication bands by allowing the switch to route signals through a path that avoids direct coupling between the first and second terminals, thereby reducing signal leakage and improving reception sensitivity
2Productivity
If communication bands are placed close to or overlapping each other to increase frequency utilization, then spectral efficiency improves, but signal leakage between bands increases, causing degradation in reception sensitivity
Solution Approach 1:
The third selection terminal acts as a mediator that provides an alternative signal path when communication bands are closely spaced or overlapping. By routing signals through this intermediate terminal, the system maintains high frequency utilization while reducing harmful signal leakage between adjacent bands, thus preserving reception sensitivity
3Device complexity
If a simple switch configuration is used for band switching, then device complexity is reduced, but isolation between selection terminals is insufficient, allowing signal leakage
Solution Approach 1:
The switch configuration is segmented by adding a third selection terminal that divides the signal path into separate segments. This segmentation increases isolation between the first and second selection terminals by introducing an intermediate stage, thereby reducing signal leakage while maintaining relatively simple overall device complexity
Solution Approach 2:
The third selection terminal serves as an intermediary element that enhances isolation between other terminals without requiring complex filtering or shielding mechanisms, thus reducing signal leakage while keeping the device configuration relatively simple
Data Source
AI summary
A high-frequency front-end circuit (10) includes a band switch (20), duplexers (31, 32, and 33), and a main switch (40). The band switch (20) includes a common terminal (PC20) and selection terminals (PS21, PS22, and PS23). The main switch (40) includes a common terminal (PC40) and selection terminals (PS41, PS42, PS43). The duplexers (31, 32, and 33) are connected between the selection terminals (PS21 and PS41), between the selection terminals (PS22 and PS42), and between the selection terminals (PS23 and PS43), respectively. The selection terminal (PS23) is connected between the selection terminals (PS21 and PS22) and the selection terminal (PS43) is connected between the selection terminals (PS41 and PS42). First and second communication bands the frequency bands of which are close to or overlapped with each other are transmitted and received through the duplexers (31 and 32).