UM1657 datasheet(12/48 Pages) STMICROELECTRONICS

12 / 48 page

Hardware description

UM1657

12/48

DocID025094 Rev 1

Figure 2. STEVAL-IKR002Vx (RF module)

1.2.1

Boost mode

The SPIRIT1 can be configured to increase the output power in transmission mode.

In the default configuration the transmitter power amplifier (PA) output is biased by the 1.4 V

SMPS voltage output through the L0 external inductor (position D0 in the schematic,

Figure 3). This limits the maximum output power at about +11 dBm, measured at the 50



connector via the reference design.

Biasing the PA output through the inductor L0 directly connected to the battery, instead of

the SMPS output allows the maximum output power delivered at the 50

 connector (or at

the antenna) to be increased. The maximum output power changes with the voltage level

applied at the PA output.

To switch to the boost mode the inductor L0 must be removed from the position 1-2 D0 in

the schematic and soldered at the position 1-3 D0, then the voltage supply VCC_RF must

be provided.

UM1657 Datasheet(PDF) 12 Page - STMicroelectronics