Duplexer Inductance Lines for Attenuation and Miniaturization
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Solution Overview
Problem
Existing duplexers face challenges in achieving sufficient miniaturization and weight reduction while maintaining desired attenuation and isolation characteristics at non-passband frequency bands, particularly due to limitations in incorporating inductance components on circuit boards using flipchip mounting technology.
Innovation Solution
The duplexer design incorporates a first and second filter with specific signal and ground connections, including interconnections formed on identical or different layers of a multilayer substrate, where the orientation and direction of current flow through these interconnections enhance mutual inductive coupling, forming a series resonant circuit that increases attenuation at higher non-passband frequencies and improves isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding technique is used to connect SAW device and package terminals, then inductance component of bonding wire can be effectively used to improve attenuation characteristic at non-passband frequency band, but space and height for wire bonding is required which prevents sufficient miniaturization
Solution Approach 1:
The invention extracts the inductance function from the bonding wire (which cannot be used in flipchip mounting) and implements it through dedicated inductance lines formed on the circuit board. This allows the inductance component to be separated from the mounting method constraints, enabling both flipchip miniaturization and attenuation improvement.
Solution Approach 2:
The invention introduces inductance lines as intermediary elements on the circuit board to provide the inductance function that would otherwise be provided by bonding wires. These lines act as mediators between the flipchip-mounted SAW device and the ground, enabling attenuation improvement without requiring wire bonding space.
2Reliability
If matching circuit and inductance line are arranged in package main body with interference prevention measures, then both functions can be maintained, but ground layer and castellation are required which increase height and reduce miniaturization
Solution Approach 1:
The invention merges the inductance line and ground connection functions into a unified structure where the inductance line extends to and connects with existing ground terminals on the circuit board. This integration eliminates the need for separate ground layers and castellations, reducing package height while maintaining both matching and attenuation functions.
Solution Approach 2:
The inductance line serves multiple functions: it provides inductance for attenuation at non-passband frequencies, acts as a signal path, and connects to ground terminals for reference potential. This multi-functionality eliminates the need for dedicated ground structures, reducing overall package height.
3Volume of moving object
If inductance line is provided on circuit board to improve attenuation characteristic in flipchip mounting, then miniaturization is achieved, but sufficient inductance value and attenuation performance are difficult to obtain
Solution Approach 1:
The invention extends the inductance line in the planar dimension on the circuit board rather than using vertical structures. By optimizing the line length and path in the horizontal plane, sufficient inductance value is achieved without increasing package height, maintaining miniaturization while improving attenuation performance.
Solution Approach 2:
The invention changes the inductance parameter by optimizing the physical dimensions (length, width, trace pattern) of the inductance line on the circuit board. Through parameter optimization, sufficient inductance value is achieved within the miniaturized package constraints, enabling improved attenuation without increasing size.
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 effectively enhances attenuation and isolation characteristics at higher non-passband frequencies, enabling the duplexer to transmit and receive high-quality signals without leakage, while also achieving miniaturization of the device.
Implementation Method 1
the orientation and direction of current flow through these interconnections enhance mutual inductive coupling, forming a series resonant circuit that increases attenuation at higher non-passband frequencies
Data Source
AI summary
Provided is a demultiplexer capable of improving attenuation characteristic and isolation characteristic of a filter having a lower transmission frequency band among two filters having different transmission frequency bands, outside the transmission frequency band of a high-frequency side. A communication device using the demultiplexer is also disclosed. A first spiral wiring portion (55) and a sixth wiring portion (56) are formed so that an angle defined by a direction of a part (L1) of the first spiral wiring portion (55) and a direction of a part (L2) of the sixth spiral wiring portion (56) on a predetermined virtual plane is, for example, 0 degree and the direction of the current flowing in the part (L1) of the first spiral wiring portion (55) is opposite to the direction of the current flowing in the part (L2) if the sixth wiring portion (56).