Multiband Filter Module With Phase Tuning for Signal Leakage Suppression
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Solution Overview
Problem
Existing multi-band filter modules for communication systems suffer from large circuit size and signal leakage issues due to the need for switches at both input and output sides, leading to potential communication failures from unwanted signals.
Innovation Solution
A filter module design with a switch circuit and filters configured to short-circuit unwanted frequency bands, using surface acoustic wave or thickness extensional vibration piezoelectric filters integrated into a laminate, along with a phase adjusting circuit to suppress signal leakage, allowing for reduced module size and enhanced selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switches are provided at both input and output sides of filters, then signal switching between different frequency bands is enabled, but circuit size becomes large
Solution Approach 1:
The patent removes the unnecessary output-side switches from the circuit configuration. By analyzing the signal flow directionality, the invention extracts only the essential input-side switch needed for frequency band selection, eliminating redundant components at the output side while maintaining the core switching functionality.
Solution Approach 2:
The patent introduces a grounding mechanism as an intermediary element. The ground connection serves as a mediator to provide alternative signal paths and maintain circuit stability without requiring additional active switching components at the output, thereby reducing circuit complexity while preserving signal routing capabilities.
2Area of stationary object
If switching is performed using only a switch circuit at the input side or output side of filters, then circuit size is reduced, but signals leaked from the switch to a filter that is not selected may be transmitted
Solution Approach 1:
The patent applies preliminary anti-action by pre-establishing ground connections and filtering paths before signal leakage can occur. The grounding mechanism is configured to proactively intercept and divert leaked signals away from the output, preventing them from reaching the selected frequency band's output path.
Solution Approach 2:
The patent converts the potentially harmful leaked signals into beneficial ground-referenced paths. By strategically placing ground connections, the invention transforms leakage paths into controlled reference paths that return leaked energy to ground rather than allowing it to interfere with the selected frequency band's signal.
3Adaptability or versatility
If multiple switches and filters are used for multi-band communication, then communication across different frequency bands is enabled, but the number of components increases
Solution Approach 1:
The patent makes the input-side switch perform multiple functions: it serves as both the frequency band selection switch and provides grounding paths for leakage suppression. This multi-functional design eliminates the need for separate output-side switches, reducing the total component count while maintaining multi-band communication capability.
Solution Approach 2:
The patent merges the switching function and grounding function into a unified circuit architecture. By combining these functions and utilizing the ground as an active element in signal management, the invention reduces the number of discrete components needed while achieving both frequency selection and leakage suppression.
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 effectively reduces signal leakage and module size, enhancing selectivity and preventing unwanted signal interference, enabling efficient communication across different frequency bands.
Implementation Method 1
surface acoustic wave or thickness extensional vibration piezoelectric filters
Implementation Method 2
thickness extensional vibration piezoelectric filters
Implementation Method 3
phase adjusting circuit to suppress signal leakage
Data Source
Figure 1~2
Figure 3(A)~3(B)
Figure 4(A)~4(B)
AI summary
A common input/output portion of a switch circuit (SW) is set as a first port (P1). A first filter (F1) for passing a signal in a first frequency band is connected between a first input/output portion (T1) of the switch circuit (SW) and a second port (P2). A second filter (F2) for passing a signal in a second frequency band is connected between a second input/output portion (T2) and the second port (P2). A phase adjusting circuit (Ls) is provided such that an impedance in the second frequency band which is seen from the first port (P1) while the switch circuit (SW) selects the first input/output portion (T1) is in a substantially short-circuited state. This arrangement prevents leakage of unwanted signals from a signal path for use in a communication system not in operation among two communication systems for different frequency bands while the other communication system is engaged in communication.