Technical data

90 Agilent U7232A DisplayPort Electrical Performance Compliance Test Application
10 Source Inter Pair Skew Differential Tests
Source Inter Pair Skew Differential Test
The inter pair skew test evaluates the skew, or time delay, between
respective differential data lanes in the DisplayPort interface. (Reference
Table 3.10 VESA DisplayPort Standard).
The DisplayPort interface has the ability to skew, or deskew lanes by
20 UI (Unit Intervals) which is as much as 12ns (1.62Gb/s) and is
intended to eliminate simultaneous degradation of concurrent bytes of
transmitted data. The specification at 150 ps at the package pins (TP1),
likely to be degraded another 50 ps through the connector, is less than 0.5
UI at the highest bit rate. Therefore, it is unlikely to be a significant
reason for non- interoperability.
Channel- to- channel de- skew must be performed on the two oscilloscope
channels used for this measurement (see “Differential Probe Head Skew
Calibration" on page 223 and “SMA Probe Head Skew Calibration" on
page 229).
Test P ro ce du re
1 Start the automated testing application as described in “Starting the
DisplayPort Electrical Performance Compliance Test Application" on
page 22.
2 Connect the W2641A test fixture or other appropriate fixture to the
device under test (DUT).
3 If you are using one connection, connect the probe to one channel. If
you are using two connections, connect the two probes to two channels
of the oscilloscope. If you are using four connections, connect the four
probes to four channels of the oscilloscope.
4 Connect the SMA to SMP cable to the SMA probe head of one of the
probes and to the data lane connector on the W2641A fixture that you
want to test.
5 Connect the other SMA to SMP cable to the other SMA probe head and
to the data lane on the W2641A test fixture that you want to test.
6 In the DisplayPort Compliance Test Application, click the Set Up tab.
7 Set the Test Mode, Test Type, DUT Definition Settings, Fixture Type,
Connection Type and Number of Channels according to the type of
testing being done. Source tests are available in all the 3 test modes -
Compliance Conditions Only, User Defined Conditions and Targeted
Characterization Testing.