Antiresonance-Corrected Resonator Filter for Wider Bandwidth
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Solution Overview
Problem
Current filters, such as film bulk acoustic resonators (FBARs), face challenges in achieving optimal bandwidth and insertion loss characteristics due to limitations in adjusting antiresonance frequencies and quality factors, especially when increasing bandwidth requires high inductance, which can deteriorate attenuation characteristics.
Innovation Solution
The proposed filter design includes a series unit with series resonators, a shunt unit between series resonators and ground, and a correction unit with inductors and capacitors configured in specific arrangements to adjust antiresonance frequencies and improve bandwidth, featuring a series correction unit and a shunt correction unit with inductors and capacitors connected in series and parallel configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high inductance is used to increase bandwidth, then bandwidth is improved, but attenuation characteristics deteriorate
Solution Approach 1:
The filter is divided into multiple resonator units (series resonators and shunt resonators) that can be independently designed and optimized. Each resonator contributes to the overall bandwidth while maintaining individual quality factors, allowing bandwidth expansion without sacrificing attenuation characteristics.
Solution Approach 2:
Series resistors are introduced as intermediary elements to dampen spurious resonances and improve attenuation characteristics. These resistors are strategically placed in series with the resonators to control unwanted frequency responses without significantly impacting the main bandwidth performance.
2Productivity
If antiresonance frequency is adjusted to improve bandwidth, then bandwidth is improved, but quality factor deteriorates
Solution Approach 1:
Different resonators are designed with locally optimized quality factors based on their specific frequency roles. Series resonators and shunt resonators have different quality factor requirements, and each is tuned independently to achieve optimal performance at its operating frequency while contributing to the overall bandwidth.
Solution Approach 2:
The filter employs multiple resonators with different resonance and antiresonance frequency parameters to achieve broadband operation. By carefully selecting and adjusting these parameters for each resonator, the overall filter bandwidth is expanded while maintaining acceptable quality factors across the operating range.
3Ease of manufacture
If filter structure is simplified for ease of manufacture, then ease of manufacture is improved, but ability to adjust antiresonance frequency deteriorates
Solution Approach 1:
The resonator structures incorporate adjustable geometric parameters (such as electrode dimensions, piezoelectric layer thickness, and electrode patterns) that can be modified during manufacturing to tune antiresonance frequencies. This allows frequency adjustment while maintaining a relatively simple overall filter structure that is amenable to standard fabrication processes.
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 enhances the filter's bandwidth and insertion loss characteristics, preventing deterioration of quality factors and attenuation characteristics, resulting in improved performance by effectively adjusting antiresonance frequencies and widening the bandwidth.
Implementation Method 1
an electric field is induced in a piezoelectric layer by an electric energy applied to first and second electrodes, and a piezoelectric phenomenon may occur in the piezoelectric layer by the induced electric field, thereby causing the resonating unit to vibrate in a predetermined direction
Implementation Method 2
a bulk acoustic wave may be generated in the same direction as the direction in which the resonating unit is vibrating, thereby generating resonance
Data Source
AI summary
A filter comprises a series unit comprising a plurality of series resonators, a shunt unit comprising a plurality of shunt resonators, connected between the plurality of series resonators and a ground, and a correction unit comprising an inductor unit connected between both ends of at least one of a set of series resonators of the plurality of series resonators and a set of shunt resonators of the plurality of shunt resonators, and an impedance unit connected between the inductor unit and a ground.