31W at 870 MHz — the RF final-stage workhorse
The NXP AFT09MS031NR1 is an LDMOS RF power transistor delivering 31 W output at 870 MHz, with a gain of 17.2 dB at a test current of 500 mA and a supply of 13.6 V. It is housed in a TO-270AA surface-mount package (supplier device package TO-270-2) and rated for a maximum drain voltage of 40 V. This part is designed for base station and industrial RF amplifier final stages in the 870 MHz band, where LDMOS technology offers the linearity and efficiency needed for modulated waveforms.
Gain and bias — setting the drive chain
The 17.2 dB gain figure is measured at 500 mA quiescent current and 13.6 V drain supply. This gain level means the driver stage preceding this transistor needs to deliver roughly 1.8 W to saturate the 31 W output. The LDMOS process keeps the gain flat across the band, so the bias point can be set for class AB operation without sacrificing linearity at backed-off power levels.