This part is a kind of semiconductor called BFG520.

Function of this product has NPN 9 GHz wideband transistor.

Manufacturers : NXP

Image and pinout :

Some of the text within the PDF file :

DISCRETE SEMICONDUCTORS DATA SHEET BFG520; BFG520/X; BFG520/XR NPN 9 GHz wideband transistor Product specification File under Discrete Semiconductors, SC14 September 1995 Philips Semiconductors Product specification NPN 9 GHz wideband transistor FEATURES • High power gain • Low noise figure • High transition frequency • Gold metallization ensures excellent reliability. DESCRIPTION NPN silicon planar epitaxial transistors, intended for applications in the RF frontend in the GHz range, such as analog and digital cellular telephones, cordless telephones (CT1, CT2, DECT, etc.), radar detectors, pagers and satellite TV tuners (SATV) and repeater amplifiers in fibre-optic systems. The transistors are encapsulated in 4-pin, dual-emitter plastic SOT143 and SOT143R envelopes. PINNING [ ... ]

BFG520 PDF Datasheet Download