Signal Interpolation for Precise Threshold-Crossing Jitter Timing

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Solution Overview

Problem

Current methods for determining event timings in signals are complex and lack a simple, cost-efficient approach, particularly in modern serial data communications where jitter analysis is crucial but challenging due to the presence of deterministic and random jitter components.

Innovation Solution

A signal interpolation method that digitizes an analog input signal, identifies crossings with a threshold, and interpolates between successive samples using linearly sloped signal portions to generate a waveform that can be processed for jitter component separation, allowing for improved estimation of event timings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Clock Data Recovery (CDR) is used to identify event timings, then timing accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvetiming accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential timing information needed for jitter analysis by directly detecting zero-crossings of the analog signal against a threshold, rather than implementing a full CDR system. This extraction approach achieves sufficient timing accuracy for jitter measurement while avoiding the complexity of complete clock recovery infrastructure.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If spectrum analysis is used to separate deterministic and random jitter, then jitter component separation is improved, but device complexity increases

Engineering Contradiction:
Improvejitter component separationVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a simple analog threshold detector that generates timing marks for jitter analysis. This disposable-like simple component performs the essential function of identifying signal transitions without requiring complex spectrum analysis equipment, achieving cost-effective jitter measurement while maintaining adequate separation capability between deterministic and random components.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Device complexity

If simple threshold crossing detection is used, then device complexity is reduced, but timing precision deteriorates due to sampling limitations

Engineering Contradiction:
Improvedevice complexityVSAvoidtiming precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary analog threshold detection on the continuous signal before digitization, generating precise timing marks at the actual zero-crossing points. This preliminary action captures the exact timing information in the analog domain, avoiding the timing quantization errors that would occur if threshold detection were performed only after digital sampling, thus maintaining high timing precision with simple device architecture.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4030319A1Signal interpolation method and measurement instrument
Publication Date: 2022.07.20 ROHDE & SCHWARZ GMBH & CO KG
  • EP4030319A1 patent drawingFigure 1~2
  • EP4030319A1 patent drawingFigure 3~4
  • EP4030319A1 patent drawing

AI summary

The invention relates to a signal interpolation method. The method comprises the steps of: - Receiving an analog input signal, - Digitizing the analog input signal received, thereby obtaining a digitized input signal having samples, - Determining a crossing of the digitized input signal with respect to a threshold that was set, and - Interpolating a signal between at least two successive samples, wherein the signal interpolated has two signal portions each having a linear slope, and wherein one of the signal portions crosses the threshold. The invention also provides a measurement instrument.