Acoustic Wave Filter Circuit for Wideband Phase Cancellation
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Solution Overview
Problem
Existing acoustic wave filters and multiplexers face challenges in achieving sufficient attenuation and isolation characteristics, especially with wider frequency bands, due to difficulties in phase adjustment with traditional configurations.
Innovation Solution
Incorporating an additional circuit with a resonator group of IDT electrodes, a capacitive element, and an inductance element electromagnetically coupled to the filter circuit, allowing for phase adjustment across a wider frequency band and improved signal cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional cancellation circuit with a longitudinally coupled resonator is used, then the filter achieves basic attenuation characteristics, but phase adjustment is difficult in wider frequency bands and sufficient isolation characteristics cannot be realized
Solution Approach 1:
The cancellation circuit is segmented into multiple functional modules: a resonator group with multiple IDT electrodes for frequency-selective signal generation, a capacitive element for reactance control, and an inductance element for impedance matching. This segmentation allows independent optimization of each module's performance across different frequency ranges, enabling effective phase adjustment in wide frequency bands while maintaining attenuation characteristics.
Solution Approach 2:
The circuit employs dynamic phase adjustment mechanisms where the resonator group and capacitive element work together to provide variable reactance that can be tuned across different frequency bands. The inductance element coupled to the filter circuit enables dynamic impedance transformation, allowing the cancellation circuit to adapt its phase characteristics to match the filter's response across a wide frequency range, thereby achieving sufficient isolation characteristics.
2Adaptability or versatility
If the frequency band of the filter is widened, then the filter covers more operational ranges, but phase adjustment becomes more difficult and sufficient attenuation and isolation characteristics are hard to realize
Solution Approach 1:
The cancellation circuit is designed with multi-functional components that can operate effectively across wide frequency bands. The resonator group with multiple IDT electrodes can be configured to resonate at different frequencies, the capacitive element provides frequency-independent reactance control, and the inductance element offers broadband impedance matching. This universal design allows the circuit to maintain effective phase adjustment and signal cancellation capabilities across extended frequency ranges, preserving attenuation and isolation characteristics despite the widened operational band.
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 enhances attenuation characteristics by generating a signal opposite in phase to out-of-band components, leading to improved filter and multiplexer performance with increased attenuation and isolation.
Implementation Method 1
a first inductance element electromagnetically coupled to the filter circuit
Implementation Method 2
a resonator group including a plurality of IDT electrodes located adjacent to or in a vicinity of each other in an acoustic wave propagation direction
Data Source
AI summary
A transmission filter includes a transmission filter circuit and an additional circuit. The transmission filter circuit defines a first signal path connecting a first terminal and a second terminal. The additional circuit is connected to a first node located between the first terminal and the transmission filter circuit on the first signal path and a second node located between the second terminal and the transmission filter circuit on the first signal path and defines a second signal path connecting the first node and the second node. The additional circuit includes, on the second signal path, a resonator group, a capacitive element, and an inductance element. The inductance element is electromagnetically coupled to the transmission filter circuit.