RF front-end LNA transistor for 900 MHz bands
The NXP BFU550WX is an NPN RF transistor in a SC-70 (SOT-323) package, designed for low-noise amplifier stages up to 11 GHz. With a transition frequency of 11 GHz and a typical noise figure of 0.6 dB at 900 MHz, it fits front-end LNA positions in cellular, ISM-band, and GPS receivers where the first-stage noise floor sets the system sensitivity. The 18 dB gain at the 900 MHz band means a single stage lifts a -100 dBm antenna signal above the mixer noise floor without needing a second pre-amp.
Automotive temperature grade and bias stability
This covers the under-hood ambient of an engine bay ECU or the thermal cycling inside a headlamp module — the 150°C TJ ceiling gives margin when the transistor sits near a 105°C ambient with self-heating from the 450 mW power dissipation. DC current gain (hFE) is specified at a minimum of 60 at Ic=15 mA and Vce=8 V. This tight gain floor means the bias network stays predictable across temperature and lot variation — a common pain point when a batch of RF transistors drifts and the LNA gain flatness shifts out of spec.