XBAR Resonator Interposer Package for 3 GHz RF Bandwidth
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Solution Overview
Problem
Current RF filters are not well-suited for higher frequency bands proposed for future communications networks, particularly those above 3 GHz, as they lack the necessary bandwidth and performance to support advanced wireless communication standards like 5G and millimeter wave communication.
Innovation Solution
The development of transversely-excited film bulk acoustic resonators (XBARs) that utilize a thin film conductor pattern on a piezoelectric plate, with a specific crystal orientation and attachment to a substrate, to create a bulk shear mode resonator capable of operating effectively at higher frequencies, offering high piezoelectric coupling and reduced viscous losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional RF filters are used for current communication standards, then they work adequately for frequencies below 3 GHz, but they cannot support higher frequency bands above 3 GHz required for future communications networks like 5G and millimeter wave communication
Solution Approach 1:
The patent changes the fundamental operating parameters of the resonator by transitioning from surface acoustic wave modes to bulk acoustic wave modes, and from longitudinal to transverse excitation. This parameter change enables operation at higher frequencies (above 3 GHz) while maintaining adequate bandwidth, as the bulk wave mode with transverse excitation provides both high frequency capability and wide bandwidth performance required for 5G and millimeter wave communications
2Speed
If transversely-excited film bulk acoustic resonators are designed with thin film conductor pattern on piezoelectric plate, then higher frequency operation with wider bandwidth is achieved, but manufacturing complexity increases
Solution Approach 1:
The resonator structure is segmented into distinct functional layers: a piezoelectric plate substrate, a thin film conductor pattern layer, and electrode structures. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall structural integrity, enabling high frequency operation without excessive manufacturing complexity
Solution Approach 2:
The patent transitions from two-dimensional surface acoustic wave propagation to three-dimensional bulk acoustic wave propagation with transverse excitation. This dimensional change enables higher frequency operation and wider bandwidth by utilizing the bulk properties of the piezoelectric material rather than surface effects, while the thin film conductor pattern provides the necessary transverse excitation mechanism
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
XBARs provide improved performance for RF filters by enabling operation at higher frequencies with wider bandwidths, enhancing communication systems with better insertion loss, rejection, and power handling, supporting the demands of future wireless communication standards.
Implementation Method 1
a thin film conductor pattern on a piezoelectric plate, with a specific crystal orientation and attachment to a substrate, to create a bulk shear mode resonator
Implementation Method 2
create a bulk shear mode resonator capable of operating effectively at higher frequencies, offering high piezoelectric coupling and reduced viscous losses
Data Source
AI summary
Acoustic resonator devices and filters are disclosed. An acoustic resonator chip includes a piezoelectric plate attached to a substrate. Portions of the piezoelectric plate form at least first and second diaphragms spanning respective cavities in the substrate. A first conductor pattern on the surface of the piezoelectric plate includes a first plurality of contact pads and at least first and second IDTs with interleaved fingers of each IDT on respective diaphragms. An interposer includes a second plurality of contacts pads. A plurality of conductive balls bond each of the contact pads of the first plurality of contact pads to respective contact pads of the second plurality of contact pads.