Acoustic Resonator Cascade Layout for Spurious Mode Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless transceivers, acoustic resonator cascades can experience significant interference due to constructive interference of reflected bulk waves, leading to spurious modes, which complicates filtering operations and increases device size and cost.
Innovation Solution
The acoustic resonators in one resonator cascade are spatially shifted relative to those in another, creating gaps of varying lengths between the cascades, which reduces interference by ensuring reflected waves arrive at different phases, thereby minimizing spurious modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If acoustic resonators are arranged in regular cascades, then filter structure is simple and manufacturing is easy, but reflected bulk waves constructively interfere causing spurious modes
Solution Approach 1:
The patent applies asymmetry by introducing non-uniform gap lengths between adjacent acoustic resonators in the cascade. Instead of equal spacing, the gaps are deliberately made asymmetric with varying lengths, which causes reflected bulk waves to arrive at different phases and locations, thereby destroying the constructive interference that produces spurious modes while maintaining manufacturing feasibility.
Solution Approach 2:
The patent implements local quality by making each gap between resonators have a specific different length rather than uniform spacing. This local variation in gap dimensions creates position-dependent phase shifts for reflected waves, allowing the system to eliminate spurious modes through localized structural modifications without changing the overall cascade architecture.
2Reliability
If acoustic resonators are spatially shifted to reduce spurious modes, then filter performance improves, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the gap length parameter between resonators from a uniform value to a set of varying values. This single parameter modification (gap length) is sufficient to change the wave interference characteristics and eliminate spurious modes, improving filter performance without requiring complex structural changes or additional components.
3Manufacturing precision
If uniform gaps are used between resonators, then manufacturing precision is easier to maintain, but constructive interference of reflected waves occurs
Solution Approach 1:
The patent deliberately introduces asymmetry in gap lengths between resonators, breaking the uniformity that would otherwise be easier to manufacture. This asymmetric design ensures that reflected bulk waves experience different path lengths and arrive at different phases, preventing constructive interference and spurious modes while the gap variations can still be controlled within manufacturing tolerances.
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 effectively reduces spurious modes in resonator cascades, improving filter performance and reducing device size and cost by optimizing the spatial arrangement of acoustic resonators.
Implementation Method 1
one or more acoustic resonators that can filter frequencies of RF signals using sound waves
Implementation Method 2
bulk waves propagate through a substrate to reflect off the backside of the substrate
Implementation Method 3
The reflected bulk waves of the first resonator cascade and the second resonator cascade can 'constructively' interfere
Data Source
AI summary
An apparatus is disclosed for an acoustic resonator cascade. In example aspects, the apparatus includes at least one filter circuit. The at least one filter circuit includes a substrate, a first resonator cascade, and a second resonator cascade. The substrate has a surface including a first axis and a second axis. The first resonator cascade has multiple acoustic resonators and is disposed on the surface of the substrate in a first column along the first axis. The second resonator cascade has multiple acoustic resonators and is disposed on the surface of the substrate in a second column along the first axis. A first gap extends along the second axis between the first resonator cascade and the second resonator cascade. A second gap extends along the second axis between the first resonator cascade and the second resonator cascade. The first gap is different from the second gap.