Teledyne LeCroy QPHY-HDMI - Manual (Page 23)

QPHY-HDMI Operator’s Manual
Test7-7: TMDS Intra-Pair Skew
This test confirms that any skew within any one differential pair in the TMDS portion of the HDMI
link does not exceed the limits in the specification.
R EQUIREMENT
Intra-pair skew between TMDS DATA pairs must not exceed 0.15*TBIT.
Reference: [HDMI: Table 4-16] Source AC Characteristics at TP1
M ETHODOLOGY
1. Connect TPA-P adapter to the Source DUT HDMI output connector.
2. Connect the first TF-HDMI-3.3V to TMDS_DATA0+.
3. Connect the second TF-HDMI-3.3V to TMDS_DATA0-.
4. Configure Source DUT to output a video format and pixel size with highest supported
TMDS clock frequency.
5. Set the trigger on TMDS_DATA0+ rising edge.
6. Display the waveform of TMDS_DATA0+ and DATA0-. Accumulate 10,000 or more
triggers. Find the closest falling edge of DATA0- (either preceding or following DATA0+
rising edge) and determine the most common 50% crossing point of that TMDS_DATA0-
falling edge using a horizontal (time) Histogram method.
7. Measure skew from trigger point to most common 50% crossing point of TMDS_DATA0-.
If (skew > 0.15*TBIT) then FAIL.
8. Repeat the test for all remaining TMDS differential pairs.
922540 Rev A 19