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DMI Compliance & Sink Characterization Using DTG5000 Series Data Timing Generator
Application Note
7
www.tektronix.com/signal_sources
Hardware Requirements: Test Equipment and
Peripherals For Sink Tests
Table 3 summarizes the measurement equipment and
accessories (probes, cables, etc.) required for the
sink tests just described. The list includes many
products recommended in the current version of the
HDMI compliance test specifications. Note that the
requirements for characterization and compliance
testing dif
fer somewhat, necessitating a selection
of tools contingent on the task at hand
1
.
In addition to the items in Table 3, instruments such
as digital multimeters, protocol analyzers and LCR
meters are required for certain HDMI compliance tests
beyond the scope of this document.
The high bandwidths, differential signaling, and
complex stimulus requirements of the HDMI architec-
ture place rigorous demands on the instrumentation
used in compliance and characterization testing. The
following headings summarize some essential points
to consider when choosing test equipment for HDMI
test applications.
Digital Storage Oscilloscope/Digital
Phosphor Oscilloscope
HDMI jitter tolerance tests r
equir
e a minimum r
ecord
length of 16 megapoints (16M) in the oscilloscope.
In addition, the instrument must offer a means for
recovering the embedded clock (the HDMI specification
pr
escribes softwar
e-based clock r
ecover
y) for eye
diagram measurements. The Tektronix TDS family
of digital storage oscilloscopes (DSO) and digital
phosphor oscilloscopes (DPO) can be equipped with
integrated TDSHT3 application software for automated
HDMI clock recovery, eye diagram measurements,
and more. The TDS7404B, with its four input channels,
4 GHz bandwidth, and 20 megasample-per-second
sample rate, is a good match for HDMI measurements.
Data Timing Generator
The stimulus source (generator) that provides the
TMDS signal plays a pivotal role in HDMI Sink tests.
The key challenge for a TMDS signal generator is
to provide the needed range of highly accurate
signals, and to provide precise control of the signal
parameters. For example, differential sensitivity tests
require an amplitude resolution of 20 mV. Intra-pair
skew tests require precise delay settings with
sub-picosecond resolution.
Historically, TMDS data signals have been generated
by aggregations of custom devices designed for
narrow output ranges and/or test conditions.
The Tektronix DTG5000 Series Data Timing Generator
offers a complete stimulus solution for HDMI sink
testing. The DTG5000 Series combines the power
of a data generator with the capabilities of a pulse
generator to provide a wide range and variety of
accurate test signals on multiple output channels
simultaneously. The user operates a set of simple
graphic controls to set the signal parameters
and variables.
Every DTG5000 Series instrument is configured from a
mainframe and plug-in output modules to provide the
desired number and type of signals. Channels may be
single-ended or dif
fer
ential, depending on the test
requirement. Output terminals of the plug-in channel
modules are SMA connectors that can easily be
converted to HDMI connectors using optional TPA test
adapter accessories.
The DTG5274 Data Timing Generator with its maximum
sample rate of 2.7 Gb/s or the DTG5334 with its
sample rate of 3.35 Gb/s maximum rate ar
e the
mainframes of choice for HDMI applications. Both
can support the maximum resolution of a UXGA
device with the required data rate of 1.62 Gb/s; both
of
fer contr
ollable voltage levels that suppor
t all TMDS,
timing, and jitter parameters.