Adjustable Notch Filter for Partial Attenuation at Fixed Bandwidth
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Solution Overview
Problem
Conventional notch filters face challenges in adjusting the amount of attenuation at the center frequency of the stopband, leading to unsuitable notch bandwidth for specific signal processing circuits when partial attenuation is required.
Innovation Solution
A notch filter circuit structure that includes adders, multipliers, and delay circuits, allowing for adjustment of the attenuation at the center frequency through an adjustable parameter A, while maintaining the notch bandwidth unchanged, enabling partial suppression of signal frequencies without altering the notch bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the amount of attenuation at the center frequency is decreased to partially attenuate the signal component, then the notch bandwidth becomes narrower, but this makes the filter unsuitable for signal processing circuits with specific requirements
Solution Approach 1:
The filter transfer function is segmented into multiple independent parameters: the notch bandwidth parameters (α, ω) are separated from the attenuation parameter (A). This allows the attenuation amount to be controlled independently through parameter A without affecting the notch bandwidth, which is determined by parameters α and ω. The segmentation enables partial attenuation while maintaining fixed notch bandwidth suitability.
Solution Approach 2:
The invention introduces a new parameter A (where 0 < A ≤ 1) that independently controls the attenuation amount at the center frequency. By changing parameter A, the attenuation level can be adjusted from complete (A=1) to partial (0 < A < 1) without modifying the notch bandwidth parameters. This parameter change approach resolves the contradiction by providing independent control over attenuation and bandwidth characteristics.
2Ease of operation
If conventional notch filters are used, then the notch bandwidth changes along with the attenuation amount, but this coupling prevents independent control of attenuation without affecting bandwidth
Solution Approach 1:
The transfer function parameters are segmented into independent groups: bandwidth parameters (α, ω) and attenuation parameter (A). This segmentation decouples the control of attenuation from bandwidth, allowing independent adjustment of attenuation amount through parameter A without affecting the notch bandwidth. The segmented parameter structure simplifies operation while reducing effective complexity by eliminating parameter coupling.
Solution Approach 2:
The invention introduces dynamic controllability by making parameter A adjustable independently of other filter parameters. This dynamic parameter allows real-time control of attenuation amount without requiring changes to bandwidth parameters, providing flexible and easy operation while maintaining stable bandwidth characteristics.
Data Source
AI summary
A notch filter appropriately adjusts the amount of attenuation at a center frequency of its notch band through changing or adjusting a value of an adjustable parameter A, and adaptively controls the amount of signal attenuation of a predetermined frequency component for an input signal that passes the notch filter, so as to partially suppress or partially attenuates the predetermined frequency component without affecting the size of a bandwidth of the notch filter.