Tunable Notch Filter Circuit for Switching Noise Attenuation
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Solution Overview
Problem
Existing signal chains, particularly those using switching regulators, face challenges in effectively filtering out noise components, especially the fundamental harmonic noise, due to varying switching frequencies and external factors, which can corrupt output signals and require multiple stages of filtering, increasing complexity and cost.
Innovation Solution
A notch filter circuit is integrated into the signal chain, capable of automatic resonance tuning by adjusting its center frequency and attenuation level, operating in two modes to optimize filtering performance by matching the notch filter's center frequency with the noise component's frequency and increasing attenuation in the filtering mode to minimize secondary noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple stages of filtering are used to effectively filter noise components, then filtering performance is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the center frequency and attenuation level of a single notch filter to match varying noise characteristics. The filter's parameters are modified in real-time to track the fundamental harmonic noise frequency, enabling effective filtering without requiring multiple fixed-frequency filter stages.
Solution Approach 2:
The patent implements dynamics by introducing automatic resonance tuning that continuously adapts the notch filter's center frequency to follow the switching frequency variations. This dynamic adjustment allows a single filter stage to replace multiple static filter stages, reducing complexity while maintaining filtering effectiveness.
2Reliability
If the attenuation level is increased to minimize secondary noise interference, then noise filtering is improved, but the filter may overly attenuate desired signal components
Solution Approach 1:
The patent applies local quality by concentrating high attenuation only at the specific frequency of the fundamental harmonic noise through notch filtering, while maintaining minimal attenuation at other frequencies. This selective attenuation approach preserves desired signal components outside the noise frequency band while effectively suppressing the target noise.
Solution Approach 2:
The patent uses parameter changes to dynamically adjust the attenuation level based on the detected noise characteristics. By modifying the Q-factor and center frequency of the notch filter, the system achieves high attenuation precisely where needed (at the noise frequency) while maintaining signal integrity elsewhere in the frequency spectrum.
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 notch filter circuit effectively attenuates target noise components while allowing secondary noise components to be filtered by downstream components, improving signal quality and reducing the need for multiple filtering stages, thus simplifying the system and reducing costs.
Implementation Method 1
The notch filter circuit has an input-output frequency response that includes a stopband region having a center frequency and an attenuation level
Data Source
AI summary
A circuit and method to filter a signal is provided. The circuit includes a notch filter circuit to receive an input signal and first and second tuning signals and to provide an output signal. The notch filter circuit has an input-output frequency response that includes a stopband region. The stopband region has a center frequency and has an attenuation level that is based at least on a tuning signal. The tunable filter circuit further includes a tuning circuit operable in at least two modes to generate the tuning signal. The at least two modes includes a tuning mode and a filtering mode. The tuning circuit generates the tuning signal such that the attenuation level of the stopband region is greater in the filtering mode than in the tuning mode.