Switched Acoustic Multiplexer Topology for Reduced Phase Spreading
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Solution Overview
Problem
Multiplexers with acoustic wave filters experience phase spreading issues in carrier aggregation applications, making it challenging to maintain small phase differences between carrier aggregation bands, which can lead to antenna loading problems.
Innovation Solution
A multiplexer design that includes a first filter coupled to a common node via a switch, with a matching network and a parallel circuit comprising an inductive and capacitive component, configured to reduce phase spreading by creating a difference in reflection coefficients between filters, and additional filters with fixed connections to the common node, utilizing shunt inductors and capacitors for impedance matching and phase centering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If acoustic wave filters are arranged as a multiplexer for carrier aggregation applications, then filtering capability for multiple frequency bands is improved, but phase spreading increases causing antenna loading problems
Solution Approach 1:
A parallel circuit comprising an inductive component and a capacitive component is introduced as an intermediary element between the acoustic wave filter and the common node. This parallel circuit acts as a mediator to adjust the reflection coefficient phase, reducing the phase spreading effect on the antenna port while maintaining the multiplexer's filtering capability for multiple frequency bands
Solution Approach 2:
The invention changes the electrical parameters (inductance and capacitance values) of the parallel circuit components to optimize the reflection coefficient phase characteristics. By adjusting these parameters, the phase spreading is reduced and the antenna port impedance is maintained close to open circuit across different operating bands
2Loss of energy
If filters are connected to common node via switches for selective operation, then power consumption is reduced, but phase spreading control becomes more challenging
Solution Approach 1:
The parallel circuit is specifically applied to filters that are selectively connected via switches, providing localized phase compensation only where needed. This local quality adjustment allows the switched filters to maintain proper phase characteristics without affecting the overall multiplexer performance or increasing power consumption
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 reduces phase spreading between passbands, achieving close to open impedance at the antenna port, thereby minimizing antenna loading loss and improving carrier aggregation performance.
Implementation Method 1
a matching network coupled to a node between the acoustic filter and the switch
Implementation Method 2
configured to cause a difference in phase between a reflection coefficient for the first filter at the common node in a passband of the second filter and the reflection coefficient for the first filter at the common node in a passband of the third filter to be reduced
Implementation Method 3
The first filter includes an acoustic filter arranged to filter a radio frequency signal
Implementation Method 4
A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer
Implementation Method 5
In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer
Implementation Method 6
The multiplexer includes a first filter coupled to an common node via a switch
Implementation Method 7
achieving close to open impedance at the antenna port, thereby minimizing antenna loading loss
Data Source
AI summary
Aspects of this disclosure relate to a multiplexer that includes a first filter and a second filter coupled to a common node. The first filter includes an acoustic filter arranged to filter a radio frequency signal, a matching network coupled between the acoustic filter and the common node, and a parallel circuit coupled in series between the acoustic filter and the common node. The parallel circuit includes an inductive component in parallel with a capacitive component. In certain instances, the first filter is coupled to the common node via a switch, the matching network is coupled to a node between the acoustic filter and the switch, and the parallel circuit is coupled in series between the acoustic filter and the switch. Related methods, radio frequency modules, and wireless communication devices are also disclosed.