Lamb Wave Dispersive Delay Line for Wideband Group Delay Control
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Solution Overview
Problem
Existing delay lines, particularly those using acoustic wave devices, face challenges in achieving frequency-dependent group delay and wide passband bandwidths, which are essential for advanced radio frequency electronic systems.
Innovation Solution
A dispersive delay line is designed with a piezoelectric substrate having specific thickness variations and additional materials to adjust acoustic wave propagation, enabling Lamb wave propagation with frequency-dependent group delay and a wide passband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional acoustic wave delay lines are used, then device structure is simple, but frequency-dependent group delay and wide passband bandwidth cannot be achieved
Solution Approach 1:
The piezoelectric substrate is divided into three regions with different thicknesses: a first region under the first IDT, a second region under the second IDT, and a third region between them. The third region has a greater thickness than the first and second regions, creating local thickness variations that enable frequency-dependent group delay and wide passband bandwidth while maintaining a relatively simple overall structure.
2Loss of time
If the piezoelectric substrate thickness is increased to reduce acoustic damping, then delay time increases, but the thickness must be controlled relative to wavelength
Solution Approach 1:
The thickness of the third region is specifically controlled to be less than 0.5 times the wavelength (λ) of the Lamb wave while being greater than the thicknesses of the first and second regions. This parameter optimization reduces acoustic damping and increases delay time without exceeding wavelength-proportional thickness limits that would cause other performance degradation.
3Adaptability or versatility
If additional material is added to adjust acoustic wave propagation, then dispersion characteristics are improved, but device complexity increases
Solution Approach 1:
Additional material is selectively deposited only on the third region of the piezoelectric substrate, not on the entire substrate. This localized material addition adjusts acoustic wave propagation and dispersion characteristics in the critical propagation region while minimizing overall device complexity and avoiding unnecessary material layers in other regions.
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 dispersive delay line achieves a high delay time with low acoustic damping, supports frequencies up to 10 GHz, and provides a wide frequency range with controlled dispersion characteristics, making it suitable for 5G NR applications.
Implementation Method 1
A dispersive delay line includes a piezoelectric substrate, a first interdigital transducer electrode, and a second interdigital transducer electrode
Implementation Method 2
a Lamb wave is configured to propagate from the first interdigital transducer electrode to the second interdigital transducer electrode though the third region of the piezoelectric substrate with a group delay that depends on frequency
Data Source
AI summary
Dispersive delay lines are disclosed. The dispersive delay line can include a piezoelectric substrate having a first interdigital transducer electrode on a first region of the piezoelectric substrate and a second interdigital transducer electrode on a second region of the piezoelectric substrate. The dispersive delay line is arranged such that an acoustic wave is configured to propagate from the first interdigital transducer electrode to the second interdigital transducer electrode though a third region of the piezoelectric substrate. An additional material positioned on the third region of the piezoelectric substrate can impact acoustic wave propagation velocity. Related radio frequency modules, wireless communications devices, and methods are disclosed.