Wireless Notch Filter Circuit for Parasitic Resistance Compensation
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Solution Overview
Problem
Conventional notch filters in wireless circuitry suffer from parasitic ohmic resistance in inductors, which limits their filtering and signal rejection capabilities.
Innovation Solution
A notch filter design incorporating a series inductor, series capacitors, and a shunt resistor and/or capacitor configuration to improve signal rejection at the resonant frequency while minimizing in-band signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional notch filter uses an inductor coupled in parallel with a capacitor, then the filter provides basic signal rejection at the resonant frequency, but the parasitic ohmic resistance of the inductor limits the filtering capability and signal rejection performance
Solution Approach 1:
The filter is segmented into multiple functional blocks: a first parallel LC circuit for basic filtering, a second parallel LC circuit for enhanced rejection, and a shunt resistor connected to the node between them. This segmentation allows each block to contribute differently to the overall filtering performance, with the shunt resistor specifically addressing the parasitic resistance issue by providing an additional signal path.
Solution Approach 2:
A shunt resistor is introduced as an intermediary element connected between the node of the two parallel LC circuits and ground. This shunt resistor acts as a mediator that compensates for the parasitic ohmic resistance by providing an alternative signal path, thereby improving the overall signal rejection capability without requiring the inductor to perform all filtering functions alone.
2Device complexity
If the inductor has high parasitic ohmic resistance, then the filter structure remains simple, but the filtering performance and signal rejection are limited
Solution Approach 1:
The filter is divided into distinct functional segments: two parallel LC circuits and a shunt resistor configuration. This segmentation enables improved filtering performance by distributing the filtering function across multiple components, with each segment contributing to the overall rejection of signals at the resonant frequency while maintaining a relatively simple overall structure.
Solution Approach 2:
The invention changes the circuit configuration parameters by introducing a shunt resistor connected to the node between two parallel LC circuits. This parameter change transforms the conventional single parallel LC filter into a multi-stage filter with enhanced signal rejection capability, effectively improving filtering performance through structural parameter modification rather than component selection alone.
3Reliability
If a shunt resistor is added to improve signal rejection, then the filtering capability increases, but the device complexity increases
Solution Approach 1:
The filter circuit is segmented into modular functional blocks: two parallel LC circuits and a shunt resistor. This segmentation allows the shunt resistor to be added as a distinct functional element that improves signal rejection without requiring complete redesign of the entire filter, thereby limiting the increase in overall device complexity while achieving improved performance.
Solution Approach 2:
The shunt resistor serves multiple functions: it provides an additional signal path for improved rejection at the resonant frequency, compensates for parasitic ohmic resistance effects, and works cooperatively with the parallel LC circuits. This multi-functionality allows a single additional component to address multiple performance issues, reducing the relative complexity increase compared to adding separate components for each function.
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
Enhances signal attenuation at the notch frequency with reduced sensitivity to process variations and in-band signal loss, improving the overall performance of wireless circuitry.
Implementation Method 1
A notch filter includes a series inductor having a first terminal coupled to an input and having a second terminal coupled to an output, a first series capacitor having a first terminal coupled to the input and having a second terminal coupled to a node, a second series capacitor having a first terminal coupled to the output and having a second terminal coupled to the node
Implementation Method 2
a shunt resistor having a first terminal coupled to the node and having a second terminal coupled to a power supply line
Data Source
AI summary
Wireless circuitry can include one or more notch filters. A notch filter circuit can include a series inductor having a first terminal coupled to an input and having a second terminal coupled to an output, a first series capacitor having a first terminal coupled to the input and having a second terminal coupled to a node, a second series capacitor having a first terminal coupled to the output and having a second terminal coupled to the node, and a shunt resistor having a first terminal coupled to the node and having a second terminal coupled to a ground line. The notch filter can further include a shunt capacitor coupled in series with the shunt resistor between the node and the ground line. The shunt resistor can be a tunable resistor.