Histogram Entropy Measurement for High-Speed Signal Equalization
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Solution Overview
Problem
Existing test and measurement instruments, such as oscilloscopes, face inefficiencies in measuring and optimizing high-speed signaling standards due to complex and time-consuming calculations for figures of merit like TDECQ and SNDR, particularly in applications like 100/200G/400 Gb Ethernet and PCIE Gen6, and in optimizing equalization filters like CTLE and DFE.
Innovation Solution
Employing entropy calculations through one- and two-dimensional histograms to determine optimal settings and performance metrics, using entropy values as a figure of merit for oscilloscope measurements and auto set functions, simplifying the process by calculating entropy values efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complicated calculations such as TDECQ and SNDR are used to measure performance of high-speed signaling standards, then measurement precision is improved, but calculation time and device complexity increase
Solution Approach 1:
The patent changes the measurement parameter from traditional complex figures of merit (TDECQ, SNDR) to entropy values. Entropy provides a simplified metric that can be calculated directly from histogram data already collected by the oscilloscope, eliminating the need for time-consuming complex calculations while maintaining measurement relevance for signal quality assessment
Solution Approach 2:
The patent extracts the essential information needed for performance measurement from the existing histogram data that the oscilloscope already collects during normal operation. By taking out and analyzing only the critical statistical moments and histogram characteristics, the system derives entropy values without requiring additional complex measurement procedures or calculations
2Measurement precision
If complicated calculations such as TDECQ and SNDR are used to measure performance of high-speed signaling standards, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the mathematical approach from complex multi-parameter calculations (TDECQ requiring quadrature components, SNDR requiring noise floor measurements) to a single entropy parameter that can be computed from standard histogram statistics, significantly reducing computational complexity while maintaining measurement validity
Solution Approach 2:
The patent makes the measurement system self-service by using the histogram data that the oscilloscope already collects during normal signal analysis. The system leverages existing data and processing capabilities to derive entropy values without requiring additional complex measurement functions, external equipment, or sophisticated calculation algorithms
3Measurement precision
If traditional methods for optimizing equalization filters are used, then measurement precision is maintained, but productivity decreases due to time-consuming optimization processes
Solution Approach 1:
The patent implements a feedback mechanism where entropy values calculated from measured signal data are used to guide equalization filter optimization. The entropy metric provides immediate feedback on signal quality and equalization performance, enabling rapid iterative optimization without requiring time-consuming traditional measurement procedures
Solution Approach 2:
The patent changes the optimization criterion from traditional complex figures of merit to entropy-based metrics. This parameter change enables faster convergence during optimization because entropy can be calculated directly from histogram data without requiring multiple passes of complex calculations, significantly improving productivity while maintaining optimization accuracy
Data Source
AI summary
A test and measurement device has a port to receive a signal from a device under test (DUT), one or more analog-to-digital converters (ADC) to digitize the signal to create one or more waveforms, a display, and one or more processors configured to execute code that causes the one or more processors to: generate a histogram from the waveform, the histogram having one or more dimensions; and calculate one or more entropy values for each of the one or more dimensions. A method includes receiving a signal from a device under test (DUT) at a test and measurement device, digitizing the signal using one or more analog-to-digital converters (ADC) to produce a waveform, generating a histogram from the waveform, the histogram having one or more dimensions, and calculating one or more entropy values for each of the one or more dimensions.