Acoustic Resonator 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 shift circuits to satisfy phase conditions, with resonators having varying capacitances, areas, or IDT electrode properties to minimize IMD, and uses ladder filters with parallel and series arm resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two-uplink carrier aggregation is implemented using conventional multiplexer, then simultaneous transmission in different frequency bands is enabled, but intermodulation distortion occurs and reception sensitivity deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the phase of acoustic path currents in resonators through modifying electrical equivalent circuit parameters (capacitance, inductance, resistance). By controlling phase parameters θ1Tx, θ2Tx, θ1Rx, θ2Rx to satisfy specific mathematical relationships, the invention suppresses intermodulation distortion while maintaining carrier aggregation functionality, thus resolving the contradiction between adaptability and reliability
Solution Approach 2:
The patent implements preliminary anti-action by pre-configuring the phase relationships of acoustic path currents in the resonators before signal transmission. The phase conditions |(2·θ1Tx−θ2Tx)−(2·θ1Rx−θ2Rx)|=180°±90° or |(2·θ2Tx−θ1Tx)−(2·θ2Rx−θ1Rx)|=180°±90° are designed to preemptively cancel out intermodulation distortion, preventing reception sensitivity deterioration before it occurs
2Adaptability or versatility
If multiple filters for different frequency bands are connected to common terminal, then multi-band transmission is achieved, but intermodulation distortion is generated
Solution Approach 1:
The patent changes the phase parameters of acoustic path currents in the resonators of multiple filters by adjusting their electrical equivalent circuit parameters. This allows the system to maintain multi-band transmission capability while controlling the phase relationships to suppress intermodulation distortion generation at the common terminal
Solution Approach 2:
The patent converts the potentially harmful intermodulation distortion into a beneficial effect by designing the phase relationships such that distortion components from different filters cancel each other out. The phase conditions ensure that IMD components are 180°±90° out of phase, transforming the harmful interaction into a cancellation mechanism
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 and maintains reception sensitivity by optimizing the phase relationships and resonator characteristics, enabling efficient two-uplink carrier aggregation.
Implementation Method 1
Each of the plurality of filters includes a plurality of resonators. The plurality of filters include a first transmission filter, a second transmission filter, and a first reception filter.
Implementation Method 2
each of the plurality of resonators of the first transmission filter includes an IDT electrode, each of the plurality of resonators of the first reception filter includes an IDT electrode
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 transmission band is represented as θ1Tx, 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 transmission band is represented as θ2Tx, a phase of an acoustic path current of a first reception filter at the side of the common terminal at a frequency within the first transmission band is represented as θ1Rx, and a phase of an acoustic path current of the first reception filter at the side of the common terminal at a frequency within the second transmission band is represented as θ2Rx, a multiplexer satisfies a first condition: |(2·θ1Tx−θ2Tx)−(2·θ1Rx−θ2Rx)|=180°±90°, or a second condition: |(2·θ2Tx−θ1Tx)−(2·θ2Rx−θ1Rx)|=180°±90°.