Narrowband Notch Filter for Adjacent Signal Interference
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Solution Overview
Problem
Signal processing systems on the same chip or circuit board often interfere with each other due to proximity, leading to unwanted signals that can pollute the desired signal, especially due to limited dynamic range and adjacent frequency interference.
Innovation Solution
A narrowband filter is introduced that utilizes the local oscillation frequencies of both systems to create a sharp notch filter, dynamically adjusting current or voltage to eliminate the unwanted signal by subtracting it from the input signal, thereby attenuating the interference without affecting the wanted signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple signal processing systems are placed close together on the same chip or circuit board, then system integration and space utilization are improved, but signal interference and unwanted signals between systems increase
Solution Approach 1:
A narrowband filter is introduced as an intermediary component in the signal path of the first signal processing system. This filter specifically targets and attenuates the unwanted signal generated by the second local oscillator of the second signal processing system, allowing close placement of systems while blocking interference through frequency-selective filtering.
Solution Approach 2:
The filter applies frequency-selective attenuation specifically at the frequency of the unwanted signal generated by the second local oscillator. This localized filtering approach targets only the harmful frequency component while leaving other frequencies unaffected, enabling systems to be placed close together without compromising signal integrity.
2Reliability
If a narrowband filter is added to attenuate unwanted signals, then signal quality and interference rejection are improved, but circuit complexity and component count increase
Solution Approach 1:
The filter's characteristics are dynamically adjusted by changing the local oscillator frequency of the second signal processing system. By tuning the oscillator frequency, the filter automatically adapts to different unwanted signal frequencies without requiring manual reconfiguration or additional complex control circuitry, maintaining signal quality while managing complexity through parameter tuning.
Solution Approach 2:
The system uses its own second local oscillator to generate the reference frequency for filtering. The second signal processing system's oscillator serves dual purposes: generating the desired signal for its own processing and providing the reference frequency for the narrowband filter to attenuate interference, eliminating the need for separate reference sources and reducing overall system complexity.
Data Source
AI summary
The disclosure provides a narrowband filter coupled to a signal path of a first system. The narrowband filter includes a first frequency converter, an integrator, and a second frequency converter coupled to each other in a sequence. The first frequency converter has a first input terminal receiving an input signal from the first system. The narrowband filter also includes a current generator. The current generator has a first terminal coupled to the input signal, a second terminal coupled to a first voltage, and a control terminal coupled to an output terminal of the second frequency converter. The narrowband filter dynamically adjusts a current being drawn from the signal path of the first system, as to detect and eliminate the frequency band of the unwanted signal generated by an influence of a second system close to the first system.