7. RF Performance
7.1 Conducted Power Measurements
During measurements, the BRD4174B Radio Board was attached to a Wireless Starter Kit Mainboard which was supplied by USB. The
voltage supply for the Radio Board was 3.3 V.
7.1.1 Conducted Measurements in the 169.4 MHz Band
The BRD4174B Radio Board was connected directly to a Spectrum Analyzer through its SMA connector. The supply for the RF section
(RFVDD) was 1.8 V provided by the on-chip DCDC converter. The supply for the sub-GHz power amplifier (SUBGRF_ON,
SUBGRF_OP) was 3.3 V provided by the mainboard (VBIAS through the discrete balun); for details, see the schematic of the
BRD4174B. The transceiver was operated in continuous carrier transmission mode. The output power of the radio was set to 19 dBm.
The typical output spectrum is shown in the following figure.
Figure 7.1. Typical Output Spectrum of the BRD4174B
As shown in the figure, the fundamental is a bit higher than 19 dBm so it is compliant with the 29.1 dBm fundamental limit. The unwan-
ted emissions are under their corresponding limit, so the conducted spectrum is compliant with the regulation limits.
BRD4174B Reference Manual
RF Performance
silabs.com
| Building a more connected world.
Rev. 1.00 | 14
