Ladder Multiplexer Filter Switching Without Series Path Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In communication apparatuses employing carrier aggregation, the use of multiport switches connected in series with filters leads to a deterioration of filter characteristics due to switch losses, affecting the bandpass and reflection characteristics of adjacent filters.
Innovation Solution
A multiplexer configuration that includes a ladder filter with series and parallel arm resonators, where a switch is connected in series with a parallel arm resonator closest to the common terminal, allowing it to switch between conduction and non-conduction, thereby reducing filter characteristic deterioration and improving impedance seen from the common terminal side, especially outside the pass band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multiport switch is connected in series between the antenna and each filter, then switching between different frequency bands is enabled, but the switch loss deteriorates the filter characteristics and reflection characteristics
Solution Approach 1:
The switch is extracted from the signal path connecting the antenna to the filter. Instead of placing the switch in series between the antenna and filter, the patent connects the switch between a tap point on the filter and ground, removing it from the main signal path while retaining its frequency selection functionality.
Solution Approach 2:
A tap point is introduced as an intermediary element on the filter structure. This tap point allows the switch to control signal routing without being directly in the antenna-to-filter path, enabling frequency band switching while minimizing impact on filter characteristics.
2Ease of operation
If the switch is placed in series on the path connecting the common terminal and filter output, then frequency selection is achieved, but the filter bandpass characteristics deteriorate due to switch loss
Solution Approach 1:
The switch is extracted from the critical signal path that defines filter bandpass characteristics. By placing the switch between a tap point and ground rather than in series on the main filter output path, the switch can perform frequency selection without degrading the filter's bandpass characteristics.
Solution Approach 2:
The switch is positioned locally at a specific tap point on the filter structure where it can perform frequency selection. This localized placement allows the switch to affect only specific frequency paths while leaving the main filter characteristics intact.
3Adaptability or versatility
If a common terminal is used to connect multiple filters, then carrier aggregation is enabled, but the reflection characteristic of one filter affects the bandpass characteristic of another filter
Solution Approach 1:
The switch provides dynamic control over signal routing at the common terminal. By selectively connecting different tap points to ground or signal paths, the system can dynamically adjust which filters are active, preventing reflection from one filter from affecting others and enabling clean carrier aggregation.
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
This configuration enhances the bandpass and reflection characteristics of adjacent filters by reducing switch-induced losses and allowing flexible impedance adjustment, thereby improving the overall filter performance in multiplexers.
Implementation Method 1
at least one parallel arm resonator connected between a connection node provided on the path and a ground, and a first switch which is connected in series with a first parallel arm resonator connected most nearby to the common terminal among the at least one parallel arm resonator
Data Source
AI summary
A multiplexer includes a plurality of filters, in which one input/output terminal of each of the plurality of filters is connected to a common terminal, a first filter included in the plurality of filters is a ladder filter and includes at least one series arm resonator connected on a path connecting the common terminal and another input/output terminal of the first filter, at least one parallel arm resonator connected between a connection node provided on the path and a ground, and a switch which is connected in series to a parallel arm resonator connected most nearby to the common terminal among at least one parallel arm resonator and switches between conduction and non-conduction of a node to which the parallel arm resonator is connected and the ground.