Parallel Acoustic Wave Resonator Circuit for Bulk Mode Ripple
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Solution Overview
Problem
Surface acoustic wave filters face challenges in reducing ripple in insertion loss due to bulk mode responses, and signal leakage between filters in multiplexers, which degrades performance and is difficult to implement effectively with existing technologies.
Innovation Solution
Incorporating an acoustic wave resonator in parallel with a circuit element, such as a capacitor or another resonator, with different resonant frequencies to suppress bulk mode frequencies and improve impedance, thereby reducing ripple and signal leakage in surface acoustic wave filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If surface acoustic wave filters are used, then chip size and cost are reduced, but ripple in insertion loss increases due to bulk mode responses
Solution Approach 1:
A circuit element (capacitor or resonator) with a different resonant frequency than the bulk mode frequency is introduced as an intermediary component. This circuit element is coupled to the surface acoustic wave resonator to specifically target and suppress the bulk mode response at the problematic frequency, thereby reducing insertion loss ripple while preserving the compact SAW filter design
Solution Approach 2:
The resonant frequency of the circuit element is specifically designed to differ from the bulk mode frequency of the surface acoustic wave resonator. By adjusting the electrical parameters (capacitance value or resonator frequency) of the circuit element, the suppression of bulk mode responses is optimized, reducing insertion loss ripple without affecting the main filtering function
2Volume of moving object
If surface acoustic wave filters are used, then chip size and cost are reduced, but signal leakage between filters increases
Solution Approach 1:
The circuit element acts as an intermediary that selectively interacts with bulk mode frequencies. By being coupled to the surface acoustic wave resonator, it creates a frequency-dependent impedance that suppresses signal leakage at specific frequencies while allowing the desired signal to pass through the compact SAW filter structure
3Manufacturing precision
If bulk acoustic wave filters are used, then ripple in insertion loss and signal leakage are reduced, but chip size and cost increase
Solution Approach 1:
The filter is segmented into two functional parts: the surface acoustic wave resonator that provides the main filtering function in a compact form, and the circuit element that is selectively added to suppress bulk mode responses. This segmentation allows the system to achieve bulk acoustic wave filter performance for ripple reduction while maintaining the compact size advantage of surface acoustic wave filters
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 configuration enhances the performance of surface acoustic wave filters by reducing ripple in insertion loss and signal leakage, allowing them to meet performance specifications with smaller chip size and reduced cost compared to bulk acoustic wave filters.
Implementation Method 1
surface acoustic wave resonators configured to filter a radio frequency signal
Implementation Method 2
The circuit element and the first surface acoustic wave resonator have different resonant frequencies
Data Source
AI summary
Aspects of this disclosure relate to an acoustic wave filter that includes acoustic wave resonators arranged to filter a radio frequency signal. The acoustic wave resonators include a first acoustic wave resonator. The acoustic wave filter includes a circuit element in parallel with the first acoustic wave resonator in a stage of the acoustic wave filter. The circuit element and the first acoustic wave resonator have different resonant frequencies. The circuit element can reduce an impact of bulk mode of the first acoustic wave resonator on insertion loss of the acoustic wave filter. The first acoustic wave resonator can be a surface acoustic wave resonator in certain embodiments. The circuit element can be a second acoustic wave resonator or a capacitor, for example.