Design_World_-_Internet_of_Things_Handbook_April_2020

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