Tektronix DTG5000 Series - Manual (Page 6)

HDMI Compliance & Sink Characterization Using DTG5000 Series Data Timing Generator
Application Note
6 www.tektronix.com/signal_sources 6
Intra-Pair Skew
The Sink device also must tolerate a certain amount of
intra-pair skew, that is, timing skew (misalignment)
within respective differential TMDS pairs. The CTS
standard defines a limit of 0.4 x T
BIT
for intra-pair
skew tolerance.
The test starts by setting the clock and data pairs to
zero skew and then increasing the intra-pair skew in
steps of 0.1 x T
BIT
until the Sink device displays an
error. The maximum skew setting that still provides
error-free Sink operation is defined as the intra-pair
skew; this result is compared against the published
limit. If the skew tolerance is greater than 0.4 x T
BIT
,
the device is considered compliant with the standard.
The DTG5000 Series uses its unique differential timing
offset capability in conjunction with 2 channels of a
differential DTGM30 module to fulfill this specific
test requirement.
Sink Test Instrument Jitter Min. Diff.
Requirements Tolerance Sensitivity Intra-Pair Skew Remarks
Digital Storage Oscilloscope • • • 16M record length
Differential Probes • • • > 2 ea
TPA-R Test Adapter Set • • • 013-A012-50
TPA-P Test Adapter Set • • • 013-A013-50
12 SMA Cables • • • 174-1428-00
JAE Cable Emulator • 74.25, 27MHz
DC Power Supply • • • +5V
GPIB USB Controller • • • NI GPIB-USB-B
GPIB Cable • • •
Characterization Solution
Data Timing Generator • • • DTG5274 w/ 3 DTGM30 (Note 1 )
Arbitrary Waveform Generator • AWG710/B (Note 1 )
1) SMA-BNC adaptor • 015-1018-00
Cable from DTG DC O/P Pin-to-SMA • 012-1506-00 + 015-0671-00 +
at Bias Tee (2 nos.) 015-1018-00 (Note 1 )
SMA(m) - SMA(f) Cables (2) • (Note 1 )
Mini-Circuits Bias Tee (2 nos.) • ZFBT-4R2GW (Note 1 )
Compliance Solution
Data Timing Generator • • • DTG5274 w/ 3 DTGM30/ 1
DTGM32
Function Generator up to 10MHz • 2 channel AFG3022, 3102 or 3252
2) SMA-BNC adaptor • 015-1018-00
2) SMA Cables • 174-1428-00
Table 3. Equipment for sink jitter tolerance tests.
1There are two recommended solutions for the Jitter Tolerance test; one for characterization and one for compliance. Using the AWG710B as the jitter generator allows for jitter profiles beyond compliance standards, which is
appropriate for characteriziation work. Using the DTGM32 as the jitter generator will enable testing up to the compliance specifications.