This part is a kind of semiconductor called BFG19.

Function of this product has NPN Silicon RF Transistor.

Manufacturers : Infineon Technologies AG

Image and pinout :

Some of the text within the PDF file :

BFG 19S NPN Silicon RF Transistor
For low noise, low distortion broadband 4 amplifiers in antenna and telecommunication systems up to 1.5 GHz at collector currents from 10 mA to 70 mA 3 2 1 VPS05163 ESD: Electrostatic discharge sensitive device, observe handling precaution! Type BFG 19S Maximum Ratings Parameter Marking BFG19S 1=E Pin Configuration 2=B 3=E 4=C Package SOT-223 Symbol VCEO VCES VCBO VEBO IC IB Ptot Tj TA Tstg Value 15 20 20 3 100 12 1 150 -65 ... 150 -65 ... 150 Unit V Collector-emitter voltage Collector-emitter voltage Collector-base voltage Emitter-base voltage Collector current Base current Total power dissipation , TS
75 °C 1) Junction temperature Ambient temperature Storage temperature mA W °C Thermal Resistance Junction - soldering point RthJS
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BFG19 PDF Datasheet Download