Transformer Phase Shifter Module for Parallel SAW Filter Isolation
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Solution Overview
Problem
Connecting multiple SAW filters in parallel is challenging due to interference and impedance matching issues, especially when large phase shifts are required, leading to deteriorated bandpass characteristics and increased frequency dependence of impedance.
Innovation Solution
A phase shifter module with magnetically coupled primary and secondary coils, featuring loop-shaped conductive patterns and overlapping coupling portions, reduces unwanted coupling and allows for easy connection of multiple SAW filters, achieving low frequency dependence of phase shift and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple SAW filters are connected in parallel, then filtering functionality is enhanced, but interference between filters increases and impedance matching becomes difficult
Solution Approach 1:
A phase shifter module is introduced as an intermediary component between multiple SAW filters. The phase shifter adjusts the phase of signals connected to individual terminals, enabling impedance matching and reducing mutual interference between filters by transforming their equivalent impedance states.
Solution Approach 2:
The phase shifter dynamically changes the phase parameter of signals to achieve impedance transformation. By adjusting phase shift amounts, the system transforms the equivalent impedance of SAW filters from short-circuit state to open-circuit state, thereby reducing interference and improving matching.
2Reliability
If phase shifting is performed using traditional LC circuits, then impedance matching can be achieved, but frequency dependence of impedance increases
Solution Approach 1:
Traditional LC circuit phase shifters are replaced with a transformer-based phase shifter module. This substitution eliminates the frequency-dependent impedance characteristics of LC circuits while maintaining the ability to achieve impedance matching through phase adjustment.
Solution Approach 2:
The phase shifter module changes the phase parameter of signals in a frequency-independent manner using transformer coupling. This allows impedance matching to be achieved without introducing the frequency dependence that plagues traditional LC-based solutions.
3Reliability
If large phase shifts are required for SAW filters in the third quadrant, then matching becomes very difficult, but insertion loss deteriorates
Solution Approach 1:
The phase shifter module serves as an intermediary that provides the necessary phase shift and impedance transformation without the high insertion loss associated with traditional methods. The transformer-based design efficiently transfers energy while achieving the required phase shifts for third-quadrant SAW filters.
4Area of stationary object
If multiple phase shifters are placed adjacent to each other, then compact design is achieved, but unwanted coupling between phase shifters increases
Solution Approach 1:
The phase shifter module employs asymmetric winding directions for adjacent phase shifters. This asymmetry creates opposing magnetic field polarities that cancel each other out, thereby reducing unwanted coupling between adjacent phase shifters while maintaining compact dimensions.
Solution Approach 2:
Adjacent phase shifters are designed with opposite winding directions that generate counteracting magnetic fields. These opposing fields serve as a form of magnetic counterweight, neutralizing the unwanted coupling effects and enabling compact arrangement of multiple phase shifters.
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 solution effectively reduces interference between SAW filters, enables wide-band phase inversion, and facilitates the connection of multiple filters with improved impedance matching, resulting in reduced insertion loss and increased isolation between ports.
Implementation Method 1
a primary coil and a secondary coil that are coupled to the primary coil by magnetic field coupling
Data Source
AI summary
A phase shifter module includes a base material, a common terminal, and individual terminals, the common terminal and the individual terminals being provided at the base material. Inside the base material, phase shifters that are connected between the individual terminals and the common terminal, respectively, are provided. The phase shifters each include a primary coil and a secondary coil that is coupled to the primary coil by magnetic field coupling and define a transformer phase shifter. With this configuration, a phase shifter module for use with SAW filters while reducing or preventing interference among the SAW filters, a multiplexer/demultiplexer that includes the phase shifter module, and a communication apparatus that includes the phase shifter module, are obtained.