User's Manual

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Layout Guidelines

Figure 24 describes the MIMO antenna spacing. The distance of ANT1 and ANT2 must be greater than

half of wavelength (62.5 mm @ 2.4 GHz).

Figure 24. MIMO Antenna Spacing

The supply routing guidelines are as follows:

• For power supply routing, the power trace for V

BAT

must be at least 40 mil wide.

• The 1.8-V trace must be at least 18 mil wide.

• Make V

BAT

traces as wide as possible to ensure reduced inductance and trace resistance.

• If possible, shield V

BAT

traces with ground above, below, and beside the traces.

The digital signals routing guidelines are as follows:

• SDIO signals traces (CLK, CMD, D0, D1, D2, and D3) should be routed in parallel to each other and

as short as possible (less than 12 cm). In addition, every trace length must be the same as the others.

There should be enough space between traces – greater than 1.5 times the trace width or ground – to

ensure signal quality, especially for the SDIO_CLK trace. Remember to keep them away from the

other digital or analog signal traces. TI recommends adding ground shielding around these buses.

• SDIO Clock, PCM clock… These digital clock signals are a source of noise. Keep the traces of these

signals as short as possible. Whenever possible, maintain a clearance around them.

SWRU359C–September 2013–Revised January 2014 WL1835MODCOM8B WLAN MIMO and Bluetooth

Module Evaluation Board

for TI Sitara™ Platform

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