Data Sheet

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Application schematics recommendations
silabs.com | Building a more connected world. Rev. 0.1 | 8
4 Application schematics recommendations
4.1 Power supply
WGM160P consists of two main blocks, the microcontroller EFM32GG11 and the Wi-Fi network co-processor WF200. The microcontroller
contains an internal DC-DC converter that powers both the microcontroller core and the WiFi chip with a lower supply voltage to reduce
overall power consumption. All the internal supplies are connected together and supplied by module pin VBAT.
Care should be taken that the supply source is capable of supplying enough current for the load peaks of the power amplifier which can
go momentarily up to 200mA, so it is recommended to select a regulator capable of supplying 300 mA. The peaks can be very fast, and
the power supply supplying the module should be capable of reacting to load changes within 5µs.
External high frequency bypass capacitors are not needed because the module contains the required supply filter capacitors. However,
care should be taken to prevent strong switching noise from being superimposed on the supply lines. Such noise can be generated, for
example, by on-board charge pump converters used in RS232 level shifters.
Note that there is a total of about 15 µF of low ESR ceramic capacitors inside the module connected directly on the supply input. When
using external regulators to generate regulated supplies for the module, the stability of the regulator with the low ESR provided by these
capacitors should be checked. Some low-drop linear regulators and some older switched mode regulators are not stable when using
ceramic output capacitors. The datasheet of the regulator typically lists recommendations concerning suitable capacitors, including data
on ESR range and/or stability curves. A regulator with a statement “stable with ceramic capacitors” is recommended.
4.2 RF part
When using WGM160P with an antenna external to the module, be they connectorized off-the-shelf antennas or PCB trace antennas,
antenna impedance shall be well matched to 50 ohms, achieving better than -10dB return loss throughout the 2.4-2.48 GHz band to
reduce distortion in the module power amplifier due to impedance mismatch.
The matching should be verified in the final enclosure and it is recommended to reserve SMD placeholders for external antenna tuning.
The suggested external antenna matching structure is a 3-element PI network.
Unused RF ports (RF2 on both variants or RF1 on the variant without the chip antenna assembled) must be terminated to ground with a
resistor between 47 and 51 ohms.