Duplexer Filter Loss Reduction via Resonator Segmentation
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Solution Overview
Problem
Existing duplexers face increased filter loss due to spurious responses from inductance-connected series resonators, which are placed within the passband of other filters, leading to ripple generation and difficulty in suppressing these effects.
Innovation Solution
The duplexer configuration includes series resonators with inductance connected in parallel, divided into multiple resonators in series, and piezoelectric thin film resonators with varying resonance region shapes, to shift spurious responses outside the passband and reduce filter loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inductance is connected in parallel to a series resonator to generate an attenuation pole in the lower frequency region, then the filter can achieve steep attenuation characteristics, but the spurious response of the resonator is placed in the passband of other filters, increasing filter loss
Solution Approach 1:
The series resonator having the inductance connected in parallel is divided into a plurality of resonators connected in series. This segmentation shifts the spurious response frequency away from the passband of other filters, thereby reducing filter loss while maintaining the attenuation pole generation capability.
2Reliability
If the attenuation pole is placed in the passband of another filter to achieve excellent duplexing characteristics, then duplexing performance is improved, but spurious response increases loss in that passband
Solution Approach 1:
By dividing the series resonator with parallel inductance into multiple smaller resonators, the spurious response is shifted to frequencies that do not overlap with the passband of other filters. This allows the attenuation pole to be effectively placed in the passband for good duplexing characteristics without the penalty of increased passband loss from spurious responses.
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 suppresses spurious responses and reduces filter loss, improving duplexing characteristics by placing attenuation poles outside the passband and optimizing resonator shapes to minimize ripple generation.
Implementation Method 1
piezoelectric thin film resonators with varying resonance region shapes
Data Source
AI summary
A duplexer with a reduced filter loss is provided. The duplexer includes two or more filters F1 and F2 that are connected to a common terminal and that have different passbands. At least one of the filters F1 and F2 includes a plurality of series resonators S1 to Sn connected in series to a path between an input terminal and an output terminal of the filter, and parallel resonators P1 to Pm connected in parallel to the above-mentioned path. An inductance L1 is connected in parallel to at least one of the series resonators, and the series resonator S1 having the inductance L1 connected in parallel thereto is divided into a plurality of resonators S11 to S13 connected in series.