This part is a kind of semiconductor called RT5370N.

Function of this product has highly integrated MAC/BBP and 2.4 GHz RF/PA/LNA single chip.

Manufacturers : Ralink

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Some of the text within the PDF file :

IIIIIII Application •IEEE802.11 b/g/n Wireless Local Area Networks •USB 2.0 Wi-Fi Dongle. RT5370 Datasheet Revision August 30, 2010 Product Description The RT5370 is a highly integrated MAC/BBP and 2.4 GHz RF/PA/LNA single chip with 150Mbps PHY rate supporting. It fully complies with IEEE 802.11n and IEEE 802.11 b/g feature rich wireless connectivity at high standards, delivers reliable, cost-effective, throughput from an extended distance. Optimized RF architecture and baseband algorithms provide superb performance and low power consumption. Intelligent MAC design deploys a high efficient DMA engine and hardware data processing accelerators without overloading the host processor. The RT5370 is designed to support standard based features in the areas of security, quality of service a [ ... ]

RT5370N PDF Datasheet Download