eeworldonline.com | designworldonline.com 4 • 2020 DESIGN WORLD — EE NETWORK 25
Device
under test
Device
under test
Receptacle
Fixture
Pattern
Cable PCB Fixture TX FIR generator
Plug
Fixture
Neighbor
TX
Pattern
TX FIR Generator
TP3’
ACCM
Noise
PJ RJ SSC
Software Channel
Software Channel
Calibration Path
TP3
ACCM
Noise
PJ RJ SSC
Receptacle
Fixture
Case 1:
Case 2:
Short channel and long channel
receiver test cases. The short
channel case represents a device
that plugs directly into the host
connector (such as a memory
stick) with a host controller that
is as close as possible to the
host port connector. .The long
channel represents the situation
where the USB device connects
to the controller through a
3-m-long cable.
During product turn-on, it is critical to view, trigger,
and decode on the SBTx and SBRx low-speed lines for
negotiation and debug. In parallel, it would be necessary
to view, trigger, and decode the high-speed 10-G and
20-G lanes also. Not having the ability to view all the
low-speed and high-speed lanes in parallel curbs the
ability to debug the power-on sequence.
In a nutshell, one must view testing of a USB4
design not as an independent entity but in conjunction
with the other technologies that must also be
implemented simultaneously. Hence one must also
consider design simulation, protocol, USB power
delivery, channel characterization, side-band testing,
Thunderbolt, and DisplayPort. Important as well are
the specific instrumentation, software, and fixtures for
testing the entire Type-C ecosystem. References
Keysight Technologies, USB4, https://about.keysight.com/
en/newsroom/pr/2019/12dec-nr19156.shtml
TESTING USB4