Acoustic Duplexer Interference Suppression via Band-Stop Filters
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Solution Overview
Problem
Filters operating with acoustic waves exhibit nonlinearities, leading to interfering frequency components that interfere with signal transfer, particularly third-order interference frequencies which are of the same order as desired frequencies, causing significant interference in communication bands like LTE and WLAN.
Innovation Solution
A circuit assembly with a duplexer operating with acoustic waves, incorporating band-stop filters, phase shifters, and diversity duplexer configurations to suppress interference signals by reducing their power and isolating transmission and reception paths, thereby improving linearity and reducing the impact of third-order interference frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a duplexer operating with acoustic waves is used to connect transmission and reception paths, then signal transfer capability is improved, but nonlinearities generate interfering frequency components that degrade signal quality
Solution Approach 1:
The patent extracts and removes the harmful interfering frequency components generated by the duplexer's nonlinearities through filtering mechanisms, separating the desired signal from the unwanted interference to maintain signal quality
Solution Approach 2:
The patent introduces intermediary filtering elements between the duplexer and the signal paths to mediate the interaction, preventing the harmful frequency components from directly affecting the transmission and reception signals
2Object-affected harmful factors
If third-order interference frequencies are present, then they mix with basic frequencies to create significant interference, but filtering out these frequencies while maintaining desired frequencies is difficult
Solution Approach 1:
The patent segments the frequency spectrum into distinct bands and applies targeted filtering approaches for different frequency ranges, particularly addressing third-order interference frequencies separately from the basic frequencies to reduce overall interference without requiring a single complex filter
Solution Approach 2:
The patent modifies the operational parameters of the duplexer and associated circuits to shift or minimize the generation of third-order interference frequencies, changing the frequency relationships between transmitted and received signals to avoid problematic mixing products
3Power
If transmission and reception paths are closely coupled to the antenna path, then signal strength is improved, but interference signal coupling between paths increases
Solution Approach 1:
The patent converts the harmful coupling effect into a beneficial isolation mechanism by using the same physical coupling structure to enable selective signal routing, where the close coupling allows strong signal transfer while the filtering elements prevent interference by allowing desired frequencies to pass while blocking unwanted frequencies
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 proposed solution effectively reduces the power of interference signals, improving signal transfer by suppressing third-order interference frequencies, enhancing the linearity of the duplexer, and minimizing interference in communication bands, as demonstrated by improved signal strength and reduced nonlinearity in the circuit assembly.
Implementation Method 1
electroacoustic transducers convert between RF signals and acoustic waves
Implementation Method 2
a band-stop filter in the antenna path. The band-stop filter having a stop band adapted to the interference signals significantly reduces the power of an interference signal
Implementation Method 3
A first phase shifter is interconnected between the antenna path and the transmission path... a second phase shifter can be interconnected between the antenna path and the reception path
Implementation Method 4
a diversity duplexer circuit... the latter comprises a node in the antenna path, wherein the node is connected to a further signal path, in which a filter is connected to ground in series via an impedance
Data Source
AI summary
The present invention relates to a circuit assembly which comprises an antenna path (A1), which can be connected to a first antenna (ANT1), a transmission path (TX1), a reception path (RX1), a duplexer (DPX1), operating with acoustic waves, which connects the transmission and reception paths (TX1, RX1) in each case to the antenna path (A1), and means for suppressing an interference signal.