Multi-frequency capacitance cancellation in acoustic filter circuits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Acoustic resonators in acoustic filter circuits can create electrical capacitance that causes them to resonate at multiple operating frequencies outside the series resonance frequency, compromising their performance.
Innovation Solution
A negative capacitance circuit is provided in parallel to the acoustic resonator, configured to present multiple negative capacitances at specific operating frequencies, thereby canceling or reducing the electrical capacitance and improving the acoustic filter circuit's performance across a broader frequency bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a negative capacitance circuit is added in parallel to cancel electrical capacitance at multiple operating frequencies, then the acoustic filter circuit's performance across broader frequency bandwidth is improved, but the device complexity increases
Solution Approach 1:
The negative capacitance circuit is designed to provide multiple negative capacitance values at different operating frequencies using a single circuit configuration. This multi-functional approach allows one circuit to cancel capacitance effects across multiple frequency bands (e.g., LTE uplink, LTE downlink, NR uplink, NR downlink), thereby improving frequency bandwidth performance without proportionally increasing device complexity
Solution Approach 2:
The circuit employs variable components (such as switches and可调 capacitors/inductors) that can change their electrical parameters dynamically. By adjusting the capacitance and inductance values through switching different components in or out of the circuit, the negative capacitance circuit can adapt to different operating frequencies, achieving broad frequency bandwidth coverage while maintaining a relatively compact circuit structure
2Adaptability or versatility
If the acoustic resonator operates at multiple frequencies, then the versatility of the acoustic filter circuit is improved, but the unwanted resonances compromise the performance
Solution Approach 1:
The negative capacitance circuit is designed to preemptively counteract the unwanted resonances caused by electrical capacitance at multiple operating frequencies. By introducing negative capacitance values that are equal in magnitude but opposite in sign to the parasitic capacitance effects, the circuit neutralizes the harmful resonance effects before they can degrade signal rejection performance, thereby maintaining reliability across multiple frequency bands
Solution Approach 2:
The invention converts the harmful effect of electrical capacitance (which causes unwanted resonances) into a beneficial effect. By deliberately introducing negative capacitance through the negative capacitance circuit, the parasitic capacitance is transformed from a source of performance degradation into a mechanism for resonance cancellation, thereby improving signal rejection while maintaining multi-frequency operation capability
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 implementation of the negative capacitance circuit enhances the acoustic filter circuit's performance by reducing unwanted resonances, thereby improving signal rejection and overall performance across a wider frequency range.
Implementation Method 1
The negative capacitance circuit is configured to present multiple negative capacitances each at a respective one of multiple operating frequencies in an operating frequency range nonoverlapping with the series resonance frequency
Implementation Method 2
The acoustic resonator is configured to resonate in a series resonance frequency to pass an RF signal from the input node to the output node
Data Source
AI summary
Multi-frequency capacitance cancellation in an acoustic filter circuit is provided. The acoustic filter circuit includes an acoustic resonator configured to resonate in a series resonance frequency to pass a radio frequency (RF) signal. However, the acoustic resonator may create an electrical capacitance that can cause the acoustic resonator to resonate at multiple operating frequencies outside the series resonance frequency, thus compromising performance of the acoustic resonator at these operating frequencies. Herein, a negative capacitance circuit is provided in parallel to the acoustic resonator and configured to present multiple negative capacitances to cancel (or at least reduce) the electrical capacitance at the operating frequencies. As a result, it is possible to improve the performance of the acoustic filter circuit across a broader frequency bandwidth.