Sierra Wireless AirPrime AR7582, Hardware Integration Manual

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41110461XXXX Rev 0.12 January 16, 2017 23
Hardware Integration Guide Routing Constraints and Recommendations
AR759x
RF Connector
GND
GND
GND
GND
GND
GND
ANT
50 Ohm Controlled Impedance Trace
2x Ground holdback – twice
the trace width
GND
GND
GND
GND
Figure 4. Antenna Microstrip Routing Example
3.2. USB Routing Recommendations
HighSpeed USB signals (USB_D_P / USB_D_M) are a differential pair and must be routed with the
following considerations/constraints:

90 Ohm differ/- 10% trace impedance,

Differential trace length pair matching < 2mm (15 ps),

Solid reference planes,

Trace lengths < 120 mm,

And 2x the trace width separation to all adjacent signals.
SuperSpeed USB adds two differential pairs (SSRX+ / SSRX- and SSTX+ / SSTX-). These pairs
should be routed with the following considerations/constraints:

90 Ohm differ/- 15% trace impedance,

Differential trace length pair matching < 0.7mm (5 ps),

Trace lengths < 112 mm,

And GND isolation from other adjacent traces with minimum of 2x the SSRX/SSTX trace
wdith.
3.3. Power and Ground Recommendations
Power and ground routing is critical to achieving optimal performance of the AirPrime AR758x Series
when integrated into an application.
Recommendations:

Do not use a separate GND for the Antennas.

Connections to GND from the AirPrime AR758x Series should be flooded plane using thermal
reliefs to ensure reliable solder joints.

VBATT is recommended to be routed as a wide trace(s) directly from the power supply to the
LGA pad.