BAW Resonator Layout for Nonlinearity Cancellation
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Solution Overview
Problem
Existing BAW devices face challenges in efficiently suppressing nonlinear effects such as harmonics and intermodulation distortion due to asymmetries in resonator configurations and parasitic capacitances.
Innovation Solution
The BAW device incorporates a cascade of resonators with phase-shifted excitation and includes a dummy conductor track to create symmetry between resonators, mimicking the influence of conductor tracks on acoustic and capacitive properties, thereby canceling parasitic nonlinear effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonators are connected in cascade to improve filter performance, then selectivity and rejection are enhanced, but asymmetries in resonator configurations and parasitic capacitances cause nonlinear effects such as harmonics and intermodulation distortion
Solution Approach 1:
The patent applies asymmetry principle by introducing a dummy conductor track that creates intentional asymmetry in the electrical connections to compensate for the inherent asymmetries in the resonator configurations. The dummy conductor track is designed with specific length and routing to generate parasitic capacitance that counterbalances the unwanted nonlinear effects, thereby improving filter performance while suppressing harmonics and intermodulation distortion.
Solution Approach 2:
The patent employs parameter changes by adjusting the length, routing, and configuration of the dummy conductor track to precisely control the parasitic capacitance values. By optimizing these parameters, the invention achieves cancellation of nonlinear effects while maintaining the desired filter characteristics, thus resolving the contradiction between filter performance and nonlinear distortion.
2Ease of operation
If conductor tracks are added to connect resonators, then electrical connectivity is improved, but parasitic capacitances are introduced that exacerbate nonlinear effects
Solution Approach 1:
The patent converts the harmful parasitic capacitances into a beneficial element by intentionally designing dummy conductor tracks that generate controlled parasitic capacitance. These dummy tracks are routed and dimensioned to create capacitance values that counterbalance the unwanted nonlinear effects, thereby transforming the harmful parasitic capacitance into a useful compensation mechanism that improves overall device performance.
3Object-generated harmful factors
If resonator configurations are made symmetric to reduce parasitic effects, then nonlinear effects are suppressed, but device complexity increases due to additional dummy structures
Solution Approach 1:
The patent applies segmentation by separating the functional resonator elements from the compensatory dummy elements. The dummy conductor tracks are designed as distinct segments that can be independently optimized and tuned. This segmentation allows for precise control of parasitic capacitance without requiring complete redesign of the resonator configurations, thereby reducing the overall complexity while maintaining effectiveness in suppressing nonlinear effects.
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 design effectively suppresses nonlinearities, enhancing the efficiency of BAW devices by ensuring identical acoustic and capacitive properties across resonators, leading to improved filter performance.
Implementation Method 1
The first BAW resonator and the second BAW resonator each comprise a first electrode, a second electrode and a piezoelectric layer. The piezoelectric layer is arranged in each case between the first electrode and the second electrode of the associated BAW resonator.
Implementation Method 2
The first BAW resonator and the second BAW resonator are coupled to each other... The cascade of the first and the second BAW resonator is preferably connected to a shunt resonator... effectively suppresses nonlinearities, enhancing the efficiency of BAW devices by ensuring identical acoustic and capacitive properties across resonators
Data Source
AI summary
A BAW device comprises a first BAW resonator (1) and a second BAW resonator (2). The first BAW resonator and the second BAW resonator each comprise a first electrode (11, 21), a second electrode (12, 22) and a piezoelectric layer (13, 23) being arranged in each case between the first electrode and the second electrode of the associated BAW resonator. The first electrodes, the second electrodes and the piezoelectric layers of both BAW resonators are designed essentially identically. A first conductor track (24) extends from the first electrode of the second BAW resonator to a third electric element (3) of the BAW device and electrically connects said first electrode with said third electric element. A first dummy conductor track (14) extends from the first electrode of the first BAW resonator, is electrically connected to said first electrode and, apart from said first electrode, is not electrically connected to any further electric element. The first dummy conductor track is designed such that it influences the acoustic and capacitive properties of the first BAW resonator essentially in the same way as the first conductor track influences the acoustic and capacitive properties of the second BAW resonator.