Acoustic Wave RF Combiner for Miniaturized Port Isolation
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Solution Overview
Problem
Conventional RF power combiners are bulky and difficult to miniaturize, especially for mobile wireless communication systems, due to their reliance on discrete passive elements or transmission lines, which result in high losses and impractical physical lengths for integrated circuits at frequencies below a few GHz.
Innovation Solution
A compact RF combiner utilizing bulk acoustic wave transducers with a signal path folding structure, comprising three levels of bulk wave resonators, that generates constructive interference at the output port and isolates input ports through destructive acoustic wave interference, leveraging the short acoustic wavelength for miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional discrete passive components or transmission lines are used for RF power combining, then isolation between input ports can be achieved, but the device becomes bulky and difficult to miniaturize
Solution Approach 1:
The patent replaces conventional electrical transmission lines and discrete passive components with acoustic wave transducers and acoustic transmission paths. This substitution leverages the shorter acoustic wavelength compared to electrical wavelength at the same frequency, enabling significant miniaturization of the combiner device while maintaining the required isolation between input ports through destructive acoustic wave interference
Solution Approach 2:
The invention changes the fundamental operating parameter from electrical waves to acoustic waves. By using acoustic wave propagation in piezoelectric materials, the device achieves a much shorter wavelength (and thus smaller physical dimensions) while maintaining the same functional performance for RF power combining and port isolation
2Power
If transmission line solutions are used for RF power combining, then power combination function is achieved, but the required physical length exceeds one centimeter which is hardly feasible with integrated circuits
Solution Approach 1:
The patent substitutes electrical transmission lines with acoustic waveguides and acoustic transmission paths formed by piezoelectric layers. The acoustic wavelength is significantly shorter than the electrical wavelength at the same frequency, reducing the required transmission path length from over one centimeter to a fraction of that length, making the device compatible with integrated circuit dimensions
Solution Approach 2:
The invention transitions from planar transmission line layouts to a three-dimensional stacked architecture using multiple piezoelectric layers. This vertical stacking approach further reduces the horizontal footprint and allows the power combination function to be achieved within a compact volume suitable for integrated circuits
3Power
If discrete high-value components are used for RF power combining, then power combination is achieved, but integration difficulty increases due to high resulting losses
Solution Approach 1:
The patent merges multiple functions into a single integrated acoustic combiner device. The power combination function, port isolation, and signal transmission are all achieved within one compact structure using acoustic wave transducers, eliminating the need for separate discrete high-value components and reducing overall integration difficulty
Solution Approach 2:
By replacing discrete electrical components with an integrated acoustic wave-based system, the invention achieves both power combination and port isolation in a unified structure that is easier to manufacture and integrate, while reducing the losses associated with discrete component connections
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
The solution achieves significant miniaturization and isolation between input ports, reducing insertion losses and enabling the integration of RF power combiners in portable wireless systems by exploiting the properties of acoustic wave propagation in piezoelectric materials.
Implementation Method 1
acoustic components used primarily for filtering exploit the ability of a piezoelectric material to deform under the application of an electric field. In the presence of an alternating electrical signal, acoustic waves are generated in the materials
Implementation Method 2
presenting means to generate constructive interference at the output port and to isolate the first and second input ports by destructive acoustic wave interference at the input ports
Implementation Method 3
The major advantage of these acoustic waves stems from their very low propagation speed compared to electromagnetic waves. Thus, the acoustic wavelength is very short, allowing for considerable miniaturization
Data Source
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AI summary
The combiner has two elements respectively connected to input ports (P1, P2), and a third element connected to an output port (Ps), where electrical signals are propagated between the input and output ports. The elements are formed as acoustic wave transducers (T1, T2, Ts) or Lamb-wave transducers, where the electrical signals are carried by acoustic waves propagated between the input and output ports within a medium.