Full-Wave Analysis and Design of a Wideband GaAs pHEMT MMIC LNA

This paper presents the design of a wideband monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) using GaAs pseudomorphic high electron mobility transistor (pHEMT) technology. The flat gain of 30 dB 0.5 dB is achieved using a three-stage amplifier topology over 412 GHz. The minimum noise figure of 1.0 dB is achieved in a packaging chassis within the frequency band. In order to achieve such a low noise over a wideband, several bandwidth enhancement techniques arc applied in the design. An inductive feedback at the source of the first stage results in a very wideband input matching (vertical bar S-11 vertical bar < -12 dB) over 3-15 GHz. The gold wire bonds at the input and output of the chip are separately analyzed and modeled into matching networks to ensure wideband low noise behavior of the chip after packaging. This GaAs pHEMT LNA is suitable for radio astronomy receivers such as the Atacama Large Millimeter Array Band 3 IF warm amplifiers.