Search

In this paper, a design of 3-stacked GaN highelectron-mobility transistor radio-frequency power amplifier employing an independently biased technique is presented to meet stringent requirements of next-generation wireless communication systems. The ability of independently adjusting operation conditions for each transistor of the proposed amplifier makes it possible to operate not only for high efficiency, high linearity but also for both improved efficiency and linearity. Efficiency can be optimized through varying drain bias voltages. Linearity, however, can be optimized independently through varying gate bias voltages. Importantly, both efficiency and linearity can be optimized simultaneously by making a compromise between drain and gate bias voltages. In contrast to conventional methods, the proposed configuration still ensures a compact size for design of the power amplifier. This can be feasible because the proposed solution is introduced in the device level using a MMIC technology. These superior advantages make the proposed PA a promising candidate for using in transceiver of the next-generation wireless communications systems. [ABSTRACT FROM AUTHOR]

A choledochal cyst (CC) is an abnormal congenital dilatation of the extrahepatic or intrahepatic biliary tree and is usually diagnosed during childhood. While a magnetic resonance cholangiopancreatography (MRCP) may be helpful for the diagnosis, laparoscopy and intraoperative cholangiography might be the final tool for the diagnosis and evaluation of anatomical variant and an effective surgical treatment. Herein we report a case of a 12-year-old male whose MRCP was suggestive choledochal cyst with gallbladder agenesis. He underwent an elective laparoscopic evaluation, and the intraoperative cholangiography and findings revealed that the patient was not a choledochal cyst but that the infundibulum of the huge gallbladder directly entering the main right hepatic duct with pancreaticobiliary maljunction. This case highlights that these rare entities can mimic each other on imaging; however, a laparoscopic approach and intraoperative cholangiography serves the dual purpose of diagnosing and treating this rare pathoanatomical entity. [ABSTRACT FROM AUTHOR]