Multiplexer Circuit Layout for Lower Insertion Loss
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Solution Overview
Problem
Multiplexers with inductors as phase adjustment elements face deterioration in characteristics due to increased insertion loss in the passband, particularly when inductors are placed between the common connection point and filters, leading to signal path length issues and stray capacitance.
Innovation Solution
A multiplexer design where the distance between the common connection point and the inductor on the first signal path is shorter than the distance between the inductor and the first filter, using a coil-shaped conductor inductor to enhance phase adjustment, and optimizing wiring line lengths to reduce stray capacitance and insertion loss across different passbands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inductor is arranged in series between the common connection point and a certain filter to increase impedance in the partner band, then the impedance matching in the filter's band is improved, but the signal path length increases which deteriorates the multiplexer characteristics
Solution Approach 1:
The patent introduces a shunt capacitor connected from the inductor node to ground, adding a new dimensional element (vertical connection to ground) rather than simply extending the series path. This creates an impedance transformation mechanism that achieves the desired impedance increase in the partner band without lengthening the horizontal signal path between the common connection point and the filter
Solution Approach 2:
The shunt capacitor acts as an intermediary element that mediates the impedance transformation. By placing the capacitor in parallel with the series combination of the inductor and filter, it creates an impedance network that transforms the impedance seen by the partner band signals, achieving the required impedance increase without adding series elements that would extend the signal path
2Ease of operation
If the inductor is located between the common connection point and the filter, then phase adjustment is achieved, but the signal path is not short which deteriorates the multiplexer characteristics
Solution Approach 1:
The patent adds a shunt capacitor connected to ground from the inductor node, introducing a vertical dimension to the circuit topology. This allows phase adjustment functionality to be achieved through the reactive combination of the series inductor and shunt capacitor without requiring additional series elements that would extend the signal path length and degrade multiplexer characteristics
3Ease of operation
If wiring lines are made longer to connect the common connection point and inductor, then the inductor can be positioned for phase adjustment, but stray capacitance increases which increases insertion loss
Solution Approach 1:
The patent extracts the phase adjustment function from the signal path itself and implements it through a separate LC network (series inductor with shunt capacitor to ground) connected at a specific node. This separates the phase adjustment function from the signal transmission path, allowing short wiring lines to be used while achieving the required phase adjustment through the reactive elements
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 design reduces or prevents the deterioration of multiplexer characteristics by minimizing insertion loss and stray capacitance, ensuring improved communication quality across various frequency bands.
Implementation Method 1
an inductor which is a phase adjustment element is arranged in series between the common connection point and a certain filter among the plurality of filters
Implementation Method 2
The inductor may include a substantially coil-shaped conductor
Data Source
AI summary
A multiplexer includes a first filter disposed on a first signal path, a second filter disposed on a second signal path different from the first signal path, the second filter having a passband different from that of the first filter, a common connection point at which the first signal path and the second signal path are connected to each other, and an inductor disposed in series on a path connecting the common connection point and the first filter, the path being a portion of the first signal path. On the first signal path, a distance connecting the common connection point and the inductor is shorter than a distance connecting the inductor and the first filter.