Design Study of a 120-GHz Amplifier on InP HEMT Technology

Abstract

This paper presents the design and analysis of an amplifier operating at 120 GHz, based on a domestically developed 100 nm InP HEMT process. The maximum available gain (MAG) of three transistor types in the process was compared through simulation. Among them, the 2F20 device exhibited the most stable gain characteristics, making it suitable for high-frequency amplifier design. A single-stage common-source amplifier was fabricated, and its small-signal performance was experimentally verified. The measurement results showed a gain of approximately 3 dB and input and output return loss (|S11| and |S22|) below −4 dB in the target band, which are in good agreement with simulation results. In addition, a planar Marchand balun was designed using a single-metal-layer process. However, the measured insertion loss was significantly higher than predicted by simulation, indicating the need for further research. Finally, a differential two stage amplifier was designed and simulated, achieving a gain of 15.4 dB and a 3 dB bandwidth of 18 GHz at 120 GHz.