Single-Substrate Hybrid Filter for Bandwidth and Area Efficiency
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Solution Overview
Problem
Current acoustic filter structures, such as ladder-type and lattice structures using SAW or BAW resonators, face limitations in bandwidth and area efficiency, particularly in high-frequency applications, leading to the need for non-standard topologies and increased area consumption when combining BAW and LC elements on separate substrates.
Innovation Solution
A hybrid filter is created using a single substrate with a ladder-type or lattice arrangement of BAW resonators and LC elements, where LC elements are formed through multi-level metallization with MIM-capacitors and coils, interconnected by conductor lines and vias, allowing for reduced area consumption and electrical losses by integrating both technologies on a single device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If BAW and LC elements are combined on separate substrates, then the filter can achieve high bandwidth and steep pass-band skirts, but the area consumption increases significantly
Solution Approach 1:
The patent combines BAW resonators and LC elements on a single substrate, merging two previously separate technologies into one integrated device. This eliminates the need for separate substrates and reduces overall area consumption while maintaining the complementary performance benefits of both BAW (steep skirts, high Q) and LC (high bandwidth) elements.
Solution Approach 2:
The single substrate serves multiple functions by supporting both BAW resonator fabrication and LC element integration. The substrate acts as a common platform that enables both acoustic wave resonators and planar LC circuits to coexist and interact, achieving multi-functionality in a single device structure.
2Loss of energy
If BAW and LC elements are combined on separate substrates, then each element can be optimized independently, but the connection overhead and electrical losses increase
Solution Approach 1:
By merging BAW and LC elements on the same substrate, the patent eliminates inter-substrate connections and reduces connection overhead. The LC elements can be directly interconnected with BAW resonators through planar conductor lines on the same substrate, minimizing the number of connection points and reducing electrical losses.
Solution Approach 2:
The substrate itself acts as an intermediary that facilitates direct electrical connection between LC elements and BAW resonators. The planar conductor lines and metallization layers on the substrate serve as intermediate connection structures, replacing complex inter-substrate bonding and reducing the number of solder pads required.
3Productivity
If standard acoustic filter structures are used, then manufacturing is simplified, but the achievable bandwidth is limited to about two times the pole-zero distance
Solution Approach 1:
The patent creates a composite filter structure that combines acoustic BAW resonators with electrical LC elements on the same substrate. This composite approach leverages the high Q factor and steep skirt characteristics of BAW resonators while incorporating the high bandwidth capability of LC elements, achieving a bandwidth performance that exceeds the limitations of standard acoustic filter structures.
Solution Approach 2:
The hybrid structure allows dynamic adjustment of filter characteristics by combining the fixed acoustic resonance properties of BAW resonators with the tunable electrical properties of LC elements. This enables the filter to achieve higher bandwidth while maintaining the manufacturing simplicity of standard acoustic filter 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 approach reduces connection overhead, area consumption, and electrical losses while maintaining high bandwidth and steep pass-band skirts, addressing the limitations of standard filter structures by integrating BAW and LC elements on a single substrate.
Implementation Method 1
BAW resonators are preferred at frequencies of more than 2 GHz and in all cases where high power signals are to be handled due to their higher power resistance
Implementation Method 2
series resonators and shunt resonators are combined to generate a desired filter function e.g. a band pass function
Implementation Method 3
LC elements may also be used for forming filter structures. Though the bandwidth of LC filters is higher
Implementation Method 4
The LC elements comprise at least a metal-isolator-metal capacitor (MIM-capacitor) and a coil
Implementation Method 5
The LC elements comprise at least a metal-isolator-metal capacitor (MIM-capacitor) and a coil
Data Source
AI summary
The invention combines two filter technologies on a single device using the same substrate there for. On this substrate a filter circuit is arranged that has a ladder-type or a lattice arrangement of series and parallel impedance elements to provide a hybrid filter having for example a band pass function. The impedance elements are chosen from BAW resonators and LC elements.