Acoustic Multiplexer Phase Tuning for IMD Suppression
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Solution Overview
Problem
Conventional multiplexers experience intermodulation distortion (IMD) and deteriorated reception sensitivity during two-uplink carrier aggregation due to simultaneous transmission of signals in different frequency bands.
Innovation Solution
The multiplexer design includes specific resonator configurations and phase conditions to suppress IMD, with filters having distinct pass bands and resonators with tailored capacitances, areas, and IDT electrode properties to manage acoustic path currents effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two-uplink carrier aggregation is implemented using conventional multiplexer, then simultaneous transmission in multiple frequency bands is achieved, but intermodulation distortion occurs and reception sensitivity deteriorates
Solution Approach 1:
The patent applies local quality by configuring specific resonators with different capacitance values based on their position and function within the filter. The first resonator has a first capacitance value while the second resonator has a second capacitance value, creating localized property variations that control acoustic path current phases to suppress IMD
Solution Approach 2:
The patent changes physical parameters of the resonators, specifically the capacitance values, to control the phase relationships of acoustic path currents. By adjusting capacitance values of specific resonators, the patent modifies the electrical characteristics to achieve the required phase conditions for IMD suppression
2Adaptability or versatility
If multiple filters with different pass bands are connected to common terminal, then multi-band transmission is enabled, but phase interference between filters causes IMD
Solution Approach 1:
The patent applies preliminary anti-action by pre-configuring the resonators with specific capacitance values before operation. This preliminary configuration ensures that the acoustic path currents from different filters have phases that satisfy the suppression condition, preventing IMD generation before it occurs during simultaneous transmission
Solution Approach 2:
The patent converts the potentially harmful phase interference between filters into a beneficial effect by carefully designing the resonator capacitance values. The phase differences that would normally cause IMD are transformed into a controlled relationship where the phases satisfy the suppression condition, turning interference into a mechanism for IMD reduction
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 design effectively suppresses IMD, maintaining reception sensitivity and enabling simultaneous transmission across multiple frequency bands.
Implementation Method 1
Each of the plurality of filters includes a plurality of resonators. The plurality of filters include a first transmission filter and a second transmission filter. The first transmission filter has a first pass band. The second transmission filter has a second pass band different from the first pass band.
Implementation Method 2
In the multiplexer, in a case where an electric equivalent circuit of a specific resonator among the plurality of resonators in each of the plurality of filters is represented by using a parallel circuit including a series circuit of an equivalent resistance, an equivalent inductor, and an equivalent capacitance, and a damping capacitance
Data Source
AI summary
When a current flowing in a series circuit including an equivalent resistance, an equivalent inductor, and an equivalent capacitance in an electric equivalent circuit of a specific resonator in each filter is defined as an acoustic path current, under conditions that a phase of an acoustic path current of a first transmission filter at a side of a common terminal at a frequency within a first pass band is represented as θ1Tx1, a phase of an acoustic path current of the first transmission filter at the side of the common terminal at a frequency within a second pass band is represented as θ2Tx1, a phase of an acoustic path current of a second transmission filter at the side of the common terminal at a frequency within the first pass band is represented as θ1Tx2, and a phase of an acoustic path current of the second transmission filter at the side of the common terminal at a frequency within the second pass band is represented as θ2Tx2, a multiplexer satisfies a first condition: |(2·θ1Tx1−θ2Tx1)−(2·θ1Tx2−θ2Tx2)|=180°±90°, or a second condition: |(2·θ2Tx1−θ1Tx1)−(2·θ2Tx2−θ1Tx2)|=180°±90°.