Open-short normalization method for rapid identification of defects in branched traces with high-resolution time-domain reflectometry

Test, measurement and analysis


An open-short normalization (OSN) method eliminates defect-independent reflections to find the location and type of defects.

Time domain reflectometry (TDR) that uses electro-optical sampling provides excellent resolution at the femtosecond level and presents an understandable pulse waveform, allowing rapid identification of defects in a single trace. However, it remains difficult to identify a fault in a trace of several branches; the TDR waveform is complex. Typically, the TDR waveform of a faulty unit has fault dependent reflection (DDR) and fault independent reflection (DIR). DDR is contributed by a branch with the default; DIR is contributed by the remaining good branches. The DDR (not the DIR) is required to analyze the fault; however, the DIR tends to overwhelm the waveform, making interpretation difficult. In this work, we use an open-short normalization (OSN) method to eliminate DIR. The resulting RCD immediately identifies the location and type of the fault. The OSN method has been verified using simulations and measurements.

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