Fabrication of Linear Amplifier in Linear Modulation System

• Main Authors: Yeh, Ane-Hsang, 葉恩祥
• Other Authors: Yao-Huang Kao
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/47343239280960079039

碩士 === 國立交通大學 === 電信研究所 === 85 === A high efficiency and linear power amplifier with applications to linear modulation system has been developed in this study. It consists of two MESFET in cascode configuration. With the complementary property of phase in cascode structure, the amplifier can be driven into more nonlinear region without spectrum degradation. Therefore, the efficiency can be improved. In the mean time,a simple tuning procedure for linearization is proposed. The cascode amplifier, Unbalance BIas Cascode Amplifier, is used to compensate the phase deviation in weak saturation region. With appropriate load pull tuning, the amplifier reaches its highest efficiency 49% and has output power 20.4dBm at P3dB. By the simple tuning for phase deviation under 2 degree, the output power becomes 19.4dBm at 3dB compression point. The efficiency is 42.3%. With NADC input, the output signal modulation bandwidth appears 26dBc at offset 30kHz and 50dBc at offset 60kHz signal, which satisfy the standard of NADC.