RF Multiplexer Matching Circuit for Low-Loss Carrier Aggregation
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Solution Overview
Problem
Existing radio-frequency front-end circuits face significant losses due to the use of inductors with low quality factors, particularly when supporting multiple frequency bands through carrier-aggregation, leading to increased mismatching losses.
Innovation Solution
A multiplexer design that incorporates a common terminal connected to filters for multiple frequency bands via a matching circuit, utilizing a resonant circuit with adjustable elements and switches to dynamically adjust impedance, reducing the number of inductors and minimizing losses by functioning as both inductive and capacitive components depending on frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LC circuits are connected one by one in each path to support multiple frequency bands, then carrier-aggregation capability is achieved, but loss increases due to low quality factor of inductors
Solution Approach 1:
The patent merges multiple LC circuits into a single matching circuit that serves all frequency bands. Instead of having separate LC circuits for each band, a unified matching circuit with switches dynamically reconfigures to match different bands, reducing the total number of inductors and their associated losses.
Solution Approach 2:
The matching circuit is designed to perform multiple functions by supporting carrier-aggregation across different frequency bands while maintaining low loss. The same matching circuit structure handles both CA and non-CA operations, as well as multiple band combinations, eliminating the need for separate dedicated circuits for each function.
2Adaptability or versatility
If multiple existing matching circuits are connected to support three or more bands, then multi-band carrier-aggregation is achieved, but loss due to inductors increases significantly
Solution Approach 1:
The patent combines multiple matching circuits into a single integrated matching circuit that can dynamically reconfigure for different band combinations. This consolidation reduces the total number of inductors from what would be required in separate matching circuits, directly reducing cumulative inductor losses while maintaining support for three or more bands.
Solution Approach 2:
The matching circuit employs switches to dynamically reconfigure its topology based on the active frequency bands. This dynamic switching allows the circuit to adapt to different carrier-aggregation scenarios without requiring separate static matching circuits for each band combination, reducing the overall inductor count and associated losses.
3Reliability
If inductors are used in matching circuits for each path, then impedance matching is achieved, but quality factor is low leading to increased loss
Solution Approach 1:
The patent merges multiple inductors from separate path-specific matching circuits into a shared inductor within a unified matching circuit. This consolidation maintains impedance matching capability across all frequency bands while reducing the total number of inductors, thereby reducing cumulative losses associated with low quality factor components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves low-loss performance across multiple frequency bands during both carrier-aggregation and non-carrier-aggregation operations, reducing losses associated with inductors and mismatching, thereby enhancing the efficiency of radio-frequency signal transmission.
Implementation Method 1
a resonant circuit connected in series in a second path that connects the common terminal and the second filter and having a resonant frequency in the second frequency band, the resonant frequency being a frequency at which an impedance is minimum
Data Source
AI summary
A multiplexer (10) includes a common terminal (100c), a filter (21) that supports Band 41, a filter (22) that supports Band 40, and a filter (23) that supports Band 1Rx. A matching circuit (11) includes a capacitor (C1) connected in a path (111), a switch (SW1) connected between a ground and a node in the path (111) between the capacitor (C1) and the filter (21), a resonant circuit connected in a path (112) and having a resonant frequency in Band 40, the resonant frequency being a frequency at which an impedance is minimum, a switch (SW2) connected between the ground and a node in the path (112) between the resonant circuit and the filter (22), an inductor (L1) connected in a path (113), and a switch (SW3) connected between the ground and a node in the path (113) between the inductor (L1) and the filter (23).