User's Manual

VZ22Q LTE Module
V0.1
USI
Confidential Page 21 of 23
6. USB Layout Design
6.1 Design & Layout Rule
i. USB pair impedance: 90 ohm differential.
ii. Avoid creating unnecessary stubs on data lines. If a stub is VZ22Q voidable (for example:
ESD issue), please keep the stub as short as possible.
Figure 6-1. Layout management
iii. Keep away from other signals and power switch area.
iv. Surrounded by GND plane.
v. Recommend the length don’t exceed 4 inch.
vi. The length tolerance between USB_D+& USB_D- is ± 10 mils.
6.2 Poor Routing
i. Cross split plane.
ii. Creating a stub by test point.
iii. Fail to maintain signals parallelism.
Figure 6-1. Poor Routing