Analysis and Design of a 2-40.5 GHz Low Noise Amplifier With Multiple Bandwidth Expansion Techniques
Jiaxuan Li, Jialong Zeng, Yang Yuan, Ding He, Jingxin Fan, Cheng Tan, Zhongjun Yu
Abstract
This paper analyzes the main factors limiting the bandwidth expansion of low-noise amplifiers (LNA) and designs a broadband LNA with a bandwidth of 2-40.5 GHz. The LNA is designed using multiple bandwidth expansion methods, including cascode, resistance feedback, and cascode Darlington amplifier. The amplitude-frequency characteristics and bandwidth expansion principle of the three structures are studied theoretically based on the small-signal equivalent circuit model. Thanks to these techniques, a three-stage LNA is designed in a 0.15-μm GaAs pseudomorphic high-electron-mobility (pHEMT) process. The measured results show that the designed LNA achieves an average gain of 21.6 dB in 2-40.5 GHz while maintaining a noise figure (NF) below 3.6 dB. The measured output 1-dB gain compression point (OP1 dB) is from 4.5 to 12.8 dBm and the input/output return loss are better than 5 dB. The chip area is only 1.57 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including input and output test pads.