Compact Duplexer Splitter Circuit Design
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Solution Overview
Problem
Conventional duplexer splitter circuits, composed of LC circuits and quarter-wavelength phaselines, hinder the development of compact mobile communication equipment due to large component sizes, making it difficult to achieve a more compact design.
Innovation Solution
A duplexer with a splitter circuit that includes a phaseline connected to resonators in parallel, utilizing inductors within the package to maintain compactness, and film bulk acoustic resonators to improve power durability and frequency characteristics, allowing for shorter phaseline lengths and enhanced duplexer performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LC circuit and quarter-wavelength phaseline are used in the splitter circuit, then the duplexer achieves signal isolation functionality, but the inductor and capacitor components become large in size requiring multiple electrode pads, making the circuit difficult to compact
Solution Approach 1:
The patent extracts and removes the bulky LC circuit components (inductors and capacitors with electrode pads) from the splitter circuit. Instead, it uses a resonator circuit that achieves the same signal isolation function without requiring these large discrete components, thereby significantly reducing the circuit area while maintaining functionality.
Solution Approach 2:
The patent replaces the conventional LC circuit topology with an alternative resonator-based circuit topology. This substitution eliminates the need for physical inductor and capacitor components with their associated electrode pads, achieving the same electrical function through a different circuit configuration that is inherently more compact.
2Reliability
If a quarter-wavelength phaseline is used in the splitter circuit with a substrate having a dielectric constant of approximately 7, then the duplexer achieves signal routing functionality, but the phaseline length becomes approximately 10 mm in the 2 GHz band, which is considerably large compared to filters of 1-1.5 mm square
Solution Approach 1:
The patent changes the circuit topology parameters by introducing resonators with specific resonance frequencies into the signal path. This allows the phaseline to be much shorter than quarter-wavelength while still achieving the required signal routing and isolation functions, as the resonators provide the necessary phase and impedance transformation.
Solution Approach 2:
The patent extracts the phase-shifting and signal-routing function from the long quarter-wavelength phaseline and relocates it to compact resonator circuits. This extraction allows the physical phaseline length to be dramatically reduced while the resonators perform the phase manipulation previously requiring long transmission lines.
3Reliability
If the resonance frequency and antiresonance frequency of the resonator are set lower than the passband of the transmit filter or higher than the passband of the receive filter, then attenuation poles appear at the resonance frequencies improving duplexer characteristics, but the design complexity increases
Solution Approach 1:
The patent systematically adjusts the resonator's resonance and antiresonance frequency parameters to specific ranges (below transmit passband or above receive passband). This parameter optimization creates attenuation poles that enhance duplexer characteristics while maintaining manageable design complexity through established frequency planning guidelines.
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 solution enables a more compact duplexer design with improved performance by reducing phaseline length and introducing attenuation poles, thereby enhancing the duplexer's characteristics and power resistance.
Implementation Method 1
the resonance frequency and antiresonance frequency of the resonator are preferably lower than the passband of the transmit filter or higher than the passband of the receive filter. Thus, attenuation poles for the transmit filter and the receive filter appear at the resonance frequencies of the resonator
Implementation Method 2
said splitter circuit includes at least one phaseline connected between said antenna terminal and said receive filter
Implementation Method 3
As these inductors, the inductance of a wire or via formed within the package can be used
Data Source
AI summary
The duplexer includes a transmit filter connected between an antenna terminal and a transmit terminal, and a splitter circuit and a receive filter connected in series between the antenna terminal and the receive terminal. The splitter circuit includes at least one phaseline connected between the antenna terminal and the receive filter and at least one resonator connected in parallel with the phaseline. According to the present invention, the length of the phaseline can be made shorter, so the entire duplexer can be made more compact in size. In addition, an inductors are preferably connected between each ends of the phaseline and the resonator. In this case, the inductance of a wire or via formed within the package can be used.