Ladder Duplexer Inductor Layout for Wideband Stopband Attenuation
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Solution Overview
Problem
Conventional duplexer designs face challenges in achieving low loss, high attenuation, and downsizing, particularly in wideband applications like W-CDMA/UMTS systems, where the transmit and receive bandwidths are widely separated, leading to difficulties in maintaining attenuation across the passband and stopband.
Innovation Solution
The duplexer incorporates a ladder type filter configuration with inductors connected in parallel with series resonators closest to the antenna terminal and in series between parallel resonators and ground, allowing for increased attenuation in the stopband while reducing insertion loss and enabling downsizing through optimized inductor placement and capacitance ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional duplexer designs are used, then basic filtering function is provided, but attenuation in stopband is insufficient and insertion loss is high
Solution Approach 1:
The patent applies parameter changes by optimizing the capacitance ratios of resonators (specifically setting C1/C2 and Cr1/Cr2 within specific ranges) and adjusting the inductance values of L1 and LP1 to achieve the desired attenuation and insertion loss characteristics. This resolves the contradiction by tuning electrical parameters to simultaneously improve stopband attenuation and reduce insertion loss.
Solution Approach 2:
The patent introduces dynamic elements (inductors L1 and LP1) that can be adjusted to optimize performance. The inductor L1 connected in parallel with the series resonator and inductor LP1 connected in series between parallel resonators and ground provide dynamic tuning capability to achieve both high attenuation and low insertion loss across different operating conditions.
2Adaptability or versatility
If wideband applications are implemented, then bandwidth is increased, but attenuation maintenance becomes difficult
Solution Approach 1:
The patent applies local quality by creating different electrical characteristics in different parts of the frequency spectrum. The series resonator with parallel inductor L1 provides specific attenuation characteristics for certain frequency ranges, while the parallel resonators with series inductor LP1 provide complementary characteristics, together achieving wideband operation with maintained attenuation.
Solution Approach 2:
The patent uses a composite filter structure combining multiple resonator types (series and parallel resonators) with different inductor configurations. This composite architecture enables wideband operation while maintaining attenuation characteristics across the extended bandwidth by leveraging the complementary frequency responses of different resonator-inductor combinations.
3Reliability
If filter performance is optimized, then attenuation and loss characteristics improve, but device size increases
Solution Approach 1:
The patent merges multiple functions into a single integrated filter structure. The series resonator and parallel resonators are combined in a ladder configuration, with inductors L1 and LP1 serving dual purposes of impedance matching and attenuation enhancement, thereby achieving optimized filter performance without proportionally increasing device size.
Solution Approach 2:
The inductors L1 and LP1 serve multiple functions simultaneously: they provide impedance transformation, enhance stopband attenuation, and control the frequency response of the filter. This multi-functionality allows the device to achieve optimized performance characteristics without requiring additional separate components that would increase 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 configuration effectively increases attenuation in the stopband with low insertion loss, suppresses degradation in wide passbands, and facilitates downsizing, improving the overall performance and cost-effectiveness of the duplexer.
Implementation Method 1
one of the one or more first inductors is connected in parallel with one of the multiple series resonators that is arranged closest to the antenna terminal
Implementation Method 2
a second inductor is connected in series between ground and ground sides of two or more parallel resonators commonly connected
Implementation Method 3
ladder type filter in which a parallel resonator and multiple series resonators are included, one or more first inductors are respectively connected in parallel with one or more series resonators out of the multiple series resonators
Data Source
AI summary
A duplexer includes an antenna terminal, a first filter connected to the antenna terminal, and a second filter connected to the antenna terminal. At least one of the first filter and the second filter is a ladder type filter in which a parallel resonator and multiple series resonators are included, one or more first inductors are respectively connected in parallel with one or more series resonators out of the multiple series resonators, and one of the one or more first inductors is connected in parallel with one of the multiple series resonators that is arranged closest to the antenna terminal.