Acoustic Multiplexer Circuit 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, then filtering capability for multiple carrier aggregation 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 that adjusts the impedance characteristics and reduces phase spreading effects, allowing the multiplexer to maintain multiple carrier aggregation bands while minimizing antenna loading problems.
Solution Approach 2:
The patent modifies the impedance parameters of the filter by adding a parallel circuit with specific inductive and capacitive values. This changes the reflection coefficient characteristics of the acoustic wave filter, thereby reducing phase spreading across different passbands and minimizing the harmful antenna loading effect while preserving multi-band filtering capability.
2Adaptability or versatility
If filters are connected to common node via switches, then adaptability for different carrier bands is improved, but phase spreading between passbands increases
Solution Approach 1:
The parallel circuit with inductive and capacitive components serves as an intermediary that compensates for the phase spreading introduced by the switch-based filter connections. By adjusting the impedance through this parallel circuit, the reflection coefficients of different filters at the common node are balanced, reducing phase spreading between passbands while maintaining adaptability for different carrier bands.
3Object-affected harmful factors
If matching network is added to reduce phase spreading, then antenna loading loss is reduced, but device complexity increases
Solution Approach 1:
The parallel circuit comprising inductive and capacitive components serves multiple functions simultaneously: it acts as part of the matching network to reduce antenna loading loss, adjusts impedance to minimize phase spreading, and maintains the adaptability of the multiplexer for different carrier aggregation bands. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity.
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 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 on which the interdigital transductor electrode is disposed. In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer.
Implementation Method 2
The parallel circuit includes an inductive component in parallel with a capacitive component. The parallel circuit of the first filter can be 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 matching network can include a shunt inductor. The matching network can include a series inductor.
Implementation Method 4
The matching network can include a shunt capacitor. The matching network can include a series capacitor.
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.