Passive CTLE Noise Filter With Variable Attenuation and Delay
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Solution Overview
Problem
Existing test and measurement systems face challenges in effectively filtering noise from signals due to the need for multiple expensive, channel-specific noise filters and the limitations of programmable active noise filters, which often introduce excessive noise and limited bandwidth.
Innovation Solution
A continuously or step-variable passive noise filter system that includes a splitter, variable attenuator, and variable delay line, allowing for programmable noise reduction without the need for multiple filters, and capable of operating at high frequency bandwidths like 70GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple individualized fixed passive noise filters are used to match different channel characteristics and signal types, then noise filtering effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a single universal passive noise filter that can be configured for different channel characteristics and signal types through programmable control of attenuation and frequency parameters. This multi-functional approach replaces the need for multiple specialized filters, reducing device complexity while maintaining noise filtering effectiveness across various test situations.
Solution Approach 2:
The patent employs dynamically adjustable filter parameters including programmable attenuation values and frequency-dependent response characteristics. This allows the single filter to adapt its behavior to match different channel characteristics and signal types in real-time, providing the flexibility previously requiring multiple fixed filters.
2Adaptability or versatility
If programmable active noise filters are used to replace multiple fixed filters, then adaptability is improved, but noise introduction increases
Solution Approach 1:
The patent replaces active electronic filtering components with a passive filtering approach that uses programmable attenuation and frequency-dependent loss characteristics. This substitution eliminates the need for active amplification or regeneration stages that introduce noise, while maintaining adaptability through software-controlled parameter adjustment.
Solution Approach 2:
The patent achieves programmability by changing physical parameters of the passive filter system, specifically attenuation levels and frequency response characteristics, rather than using active electronic components. This allows the filter to be reconfigured for different applications without introducing the noise associated with active circuitry.
3Adaptability or versatility
If programmable active noise filters are used to provide flexibility, then adaptability is improved, but bandwidth is limited
Solution Approach 1:
The patent replaces active filtering components with a passive filter design that inherently supports wider bandwidth operation. The passive architecture, combined with programmable attenuation and frequency control, enables the system to maintain adaptability across extended frequency ranges including 70GHz and beyond, overcoming the bandwidth limitations of active filters.
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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.