Teledyne LeCroy QPHY-HDMI - Manual (Page 26)

Test7-10: TMDS Data Eye Diagram
This test confirms that the differential signal on each TMDS differential data pair has an “eye
opening” (region of valid data) that meets or exceeds the limits on eye opening in the
specification.
R EQUIREMENT
Refer to the “Eye Diagram Mask at TP1 for Source Requirements.
Reference: [HDMI: Figure 4-18] Eye Diagram Mask at TP1
M ETHODOLOGY
1. Connect TPA-P-TDR to Source DUT HDMI output connector.
2. Connect the first TF-HDMI-3.3V to TMDS Clock, and configure as trigger.
3. Connect the second TF-HDMI-3.3V to TMDS_DATA0.
4. Connect 50 ohm pull-ups to each of the non-probed TMDS lines to 3.3V.
5. Configure Source DUT to output one video format for each of the following TMDS Clock
frequencies if that frequency is supported by the DUT: 27MHz (or 25MHz), 74.25MHz,
148.5MHz, and 222.75MHz, and, if not already covered, the highest DUT-supported
frequency. For each of these test frequencies, perform the following.
6. Capture the waveforms on the Digital Oscilloscope. Process with the CRU to display the
data eye diagram.
a. Set memory length to 16M samples per-channel.
b.
If test frequency is <=165MHz then set Sampling Rate ≥10GSa/s
If test frequency is >165MHz then set Sa
mpling Rate ≥20GSa/s
7. Compare the data eye to the TP1 Eye Diagram Mask. If any part of the waveform
exceeds either the high or low maximum voltage (+/- 780mV), then FAIL.
8. Shift the mask left or right through one entire TBIT to determine if any horizontal position
has no capture points within eye mask. No vertical shifting is allowed. If no shifted
position exists where no part of the waveform touches or crosses into the data eye, then
FAIL.
9. Measure the data jitter at the zero crossing point. Measurement box vertical setting: 0V
±5mV. If data jitter > 0.3*TBIT then FAIL.
10. Repeat the test for remaining TMDS_DATA pairs.
11. Repeat the test for remaining supported test frequencies. Only one video format/pixel-
size combination is required per TMDS clock rate.
22 922540 Rev A