Passive Variable Equalizer Filter for High-Bandwidth Noise Reduction
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Solution Overview
Problem
Existing test and measurement systems face challenges in effectively reducing noise and achieving high-frequency bandwidth due to the need for multiple fixed noise filters and the noise-introducing nature of programmable active filters, which are costly and difficult to manage.
Innovation Solution
A continuously or step-variable passive noise filter with a splitter, variable attenuator, and variable delay line that can be adjusted based on the test and measurement instrument channel to remove noise, allowing for a wide bandwidth and flexible noise reduction without requiring multiple filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple fixed passive noise filters are used to match different channel characteristics and data rates, then noise reduction effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a variable passive noise filter where the pole frequency can be dynamically adjusted based on the data rate and channel characteristics. This allows a single filter to adapt to different test conditions that previously required multiple fixed filters, thereby reducing device complexity while maintaining noise reduction effectiveness.
Solution Approach 2:
The patent changes the pole frequency parameter of the passive noise filter to match different data rates and channel loss characteristics. By adjusting this key parameter, the filter maintains optimal performance across various test scenarios without requiring multiple separate filters, thus resolving the contradiction between reliability and device complexity.
2Adaptability or versatility
If programmable active noise filters are used to replace multiple fixed filters, then adaptability is improved, but noise introduction and bandwidth limitations occur
Solution Approach 1:
The patent extracts the active programmable elements from the noise filter design and replaces them with passive components. This extraction eliminates the noise introduction inherent in active circuits while maintaining adaptability through variable passive elements, thus resolving the contradiction between adaptability and noise reduction.
Solution Approach 2:
The patent uses simple passive RC circuits that can be easily adjusted or replaced without the complexity and noise of active components. These passive filters, while simpler, provide sufficient adaptability for different test conditions without introducing the harmful noise effects of active programmable filters.
3Adaptability or versatility
If programmable active noise filters are used, then programmability is improved, but bandwidth extension to higher frequencies is limited
Solution Approach 1:
The patent replaces active electronic circuits with passive RC networks that have inherently higher bandwidth capabilities. The passive nature of the components allows them to operate at higher frequencies without the bandwidth limitations and noise issues of active programmable filters, thus resolving the contradiction between adaptability and speed.
Data Source
AI summary
A continuously or step variable passive noise filter for removing noise from a signal received from a DUT added by a test and measurement instrument channel. The noise filter may include, for example, a splitter splits a signal into at least a first split signal and a second split signal. A first path receives the first split signal and includes a variable attenuator and/or a variable delay line which may be set based on the channel response of the DUT which is connected. The variable attenuator and/or the variable delay line may be continuously or stepped variable, as will be discussed in more detail below. A second path is also included to receive the second split signal and a combiner combines a signal from the first path and a signal from the second path into a combined signal.