Elastic Wave Multiplexer Circuit With Lower Insertion Loss
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Solution Overview
Problem
In multiplexers, the inclusion of a phase shifter between filters results in significant insertion loss, particularly in the passband of the receiver filter, due to signal transmission through the phase shifter, which increases overall insertion loss.
Innovation Solution
A multiplexer design that includes a series arm circuit with two series arm resonators, where the first antiresonance frequency is set at or lower than the higher edge of the second passband, reducing the number of stages in the phase shifter and minimizing insertion loss by using elastic wave resonators to increase impedance in the passband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phase shifter is disposed between the filter and the common terminal to adjust the phase of the impedance, then the impedance matching is improved, but the insertion loss increases due to signal transmission through the phase shifter
Solution Approach 1:
The patent extracts and eliminates the phase shifter component from the circuit configuration. By redesigning the filter structure to inherently provide the necessary phase characteristics through its series arm circuit topology, the separate phase shifter is removed, thereby eliminating the insertion loss it caused while maintaining impedance matching performance
Solution Approach 2:
The patent merges the phase adjustment function into the filter structure itself. The series arm circuit is designed to simultaneously perform filtering and phase adjustment functions, combining what were previously separate components (filter + phase shifter) into a single integrated structure that reduces component count and signal loss
2Productivity
If the guard band of the transmitter filter and the receiver filter is narrowed to effectively use the frequency band, then the frequency band utilization is improved, but the filtering performance may deteriorate without steep cut-off characteristics
Solution Approach 1:
The patent changes the key parameter of cut-off characteristic steepness by employing elastic wave filters with inherently steep roll-off characteristics. This allows the guard band to be narrowed for better frequency utilization while the steep cut-off maintains effective filtering performance even with reduced separation between passbands
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 proposed design reduces insertion loss while maintaining the attenuation characteristics, allowing for efficient signal transmission with reduced ripples and improved power durability across the frequency bands.
Implementation Method 1
The first series arm circuit includes a first series arm resonator and a second series arm resonator... The first antiresonance frequency is at or lower than a higher edge of the second passband
Data Source
AI summary
A multiplexer includes a first filter located between a common terminal and a first terminal to pass a signal in a first passband, and a second filter located between the common terminal and a second terminal to pass a signal in a second passband. A first series arm circuit included in the first filter includes a first series arm resonator and a second series arm resonator. The first series arm circuit is connected to the common terminal not through a circuit including an elastic wave resonator and a connecting point of the circuit. The first series arm circuit has a first antiresonance frequency and a second antiresonance frequency higher than the first antiresonance frequency. The second antiresonance frequency is higher than a higher edge of the first passband. The first antiresonance frequency is at or lower than a higher edge of the second passband.