Elastic Wave Duplexer Flip-Chip Bonding Isolation
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Solution Overview
Problem
Existing surface acoustic wave duplexers face challenges in reducing size while maintaining isolation characteristics due to electromagnetic coupling between coil-shaped line patterns and filter components, which deteriorates the isolation performance.
Innovation Solution
The elastic wave duplexer employs a flip-chip bonding technique without bonding wires, with a coil-shaped line pattern formed inside the laminated board for impedance matching, and strategically locates the coil-shaped line to minimize electromagnetic coupling between the transmission and reception filters, using a balanced-unbalanced conversion function in the reception filter to enhance isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a coil-shaped line pattern is used for impedance matching, then large inductance can be achieved with small area, but electromagnetic coupling with filter components deteriorates isolation performance
Solution Approach 1:
The patent transitions from planar coil patterns to a three-dimensional folded line structure that extends through multiple layers of the substrate. This vertical dimensionality change allows achieving large inductance with small footprint while spatially separating the matching circuit from filter components to reduce electromagnetic coupling
Solution Approach 2:
The impedance matching circuit is divided into multiple discrete line segments distributed across different substrate layers. These segmented lines are strategically positioned to minimize overlap with filter components while collectively providing the required inductance value
2Volume of moving object
If flip-chip bonding technique is used, then size is reduced and bonding operation is efficient, but electromagnetic coupling between coil-shaped line and filter components occurs
Solution Approach 1:
By utilizing multiple substrate layers, the patent creates vertical separation between the flip-chip bonded filter components and the impedance matching lines. This three-dimensional arrangement reduces electromagnetic coupling while maintaining compact horizontal footprint
Solution Approach 2:
The patent introduces dielectric layers and ground planes as intermediary structures between the filter components and impedance matching lines. These intermediaries act as electromagnetic shields that reduce coupling while allowing electrical functionality to be maintained
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 approach reduces the size of the duplexer and significantly improves the isolation characteristic by preventing deterioration caused by electromagnetic coupling, while achieving large inductance with a small area footprint.
Implementation Method 1
surface acoustic wave filters using surface acoustic waves have been used for the reception filter and the transmission filter
Implementation Method 2
an elastic wave duplexer having a structure in which a transmission filter chip and a reception filter chip are flip-chip bonded
Data Source
Figure 1(a)~1(b)
Figure 2~3
Figure 4
AI summary
A compact elastic wave duplexer is provided. The elastic wave duplexer includes a transmission filter chip and a reception filter chip mounted on a laminated board. An impedance matching circuit is formed inside the laminated board. The isolation characteristics in a transmission band and a reception band are improved. The balance between the two is improved. The elastic wave duplexer (1) includes a transmission filter chip (6) and a reception filter chip (7) each formed from an elastic wave filter chip and flip-chip bonded to a laminated board (43). A coil-shaped line including coil-shaped line patterns (52, 54, and 56) is formed inside the laminated board (43). The coil-shaped line serves as an impedance matching circuit. In plan view, the transmission filter chip (6) is disposed on one side of a center line (X) passing through the center of the laminated board (43) and extending between a first edge (43A) and a second edge (43B), and the reception filter chip (7) is disposed on the other side. The coil-shaped line is disposed on the side on which the reception filter chip (7) is disposed.