Phase Interpolator Digital TDR for Short Link Diagnostics
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Solution Overview
Problem
Current time-domain reflectometry (TDR) methods face limitations in diagnostic accuracy due to the need for wide pulses to avoid interference and the constraints of sampling rates, which restrict the minimum length and distance of links that can be diagnosed, and are costly in terms of power, equipment, and data storage.
Innovation Solution
A digital TDR system utilizing a phase interpolator to process a primary clock signal, allowing for narrower pulse widths and increased diagnostic accuracy without increasing the sampling rate, by shifting the phase of the sampling clock signal to capture pulses and reflections accurately across the link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wide pulses are used in TDR to avoid interference, then diagnostic reliability is improved, but the minimum length of links that can be diagnosed increases
Solution Approach 1:
The patent segments the sampling process into multiple phases within a single clock period by utilizing phase interpolation. Instead of using one wide pulse, the system divides the measurement into multiple narrow pulse samples taken at different phases, reconstructing the complete diagnostic information from these segmented measurements.
Solution Approach 2:
The patent employs periodic sampling at different phase offsets within each clock period. By systematically varying the phase of sampling points across multiple cycles, the system achieves comprehensive coverage of the pulse waveform without requiring wide pulse durations, thus maintaining reliability while enabling diagnosis of shorter links.
2Measurement precision
If high sampling rates are used to diagnose shorter links, then diagnostic accuracy is improved, but power consumption and equipment cost increase
Solution Approach 1:
The patent changes the temporal parameter of sampling by introducing phase interpolation. Instead of increasing the sampling rate (frequency parameter), the system varies the phase position of samples within each period, achieving equivalent diagnostic accuracy for short links without the power penalty associated with higher sampling rates.
3Measurement precision
If analog-to-digital conversion is used for signal measurement, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential measurement information by sampling at strategically chosen phase points. Instead of performing full analog-to-digital conversion of the entire signal waveform, the system extracts critical amplitude and timing data through selective phase-based sampling, simplifying the measurement apparatus while maintaining diagnostic precision.
4Device complexity
If traditional TDR sampling is used, then device complexity is reduced, but diagnostic accuracy on short links deteriorates
Solution Approach 1:
The patent introduces dynamic phase adjustment capability to the sampling system. By making the sampling phase variable and controllable within each clock period, the system adapts to detect reflections in short links without requiring a complete redesign of the sampling hardware, thus improving accuracy while maintaining relatively simple device architecture.
Data Source
AI summary
A system and method for performing diagnostics of a link capable of measuring a signal pulse having a pulse width that is narrower than a sampling period of a clock signal used for data sampling. The system incorporates a phase interpolator that shifts a phase of the clock signal while preserving the sampling period of the clock signal. The method includes generating and transmitting a plurality of pulses to a link, where then each pulse is sampled according to the clock signal. After each pulse is sampled, the phase interpolator shifts the phase of the clock signal so that each pulse is sampled according to a unique phase, thereby increasing signal measurement accuracy without decreasing the sampling period.