TDR testing is currently mainly used in battery circuit board manufacturers' PCB (printed circuit boards) signal lines and device impedance testing.
There are many reasons that affect the accuracy of TDR testing, mainly reflection, calibration, reading selection, etc. Reflection will cause serious deviations in the test value of the shorter PCB signal line, especially when the TIP (probe) is used for testing. Obviously, because the TIP and the signal line contact point will cause a large impedance discontinuity, causing reflection to occur, and causing the impedance curve of the PCB signal line to fluctuate in the vicinity of about three or four inches.
Picture: ENIG immersion 4 layer Blue solder masker FR4
Such as single-ended signal lines, differential signal lines, connectors, etc. This kind of test has a requirement, which is to combine with the actual application conditions. For example, the actual rising edge of the signal line of the signal line is about 300ps, then the rising edge of the TDR output pulse signal should be set correspondingly near 300ps instead of 30ps. Left and right rising edges, otherwise the test result may be quite different from the actual application.
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