GaAs-Based Multi-Functional Beamforming MMIC for X-Band SAR Applications: Design, and Performance Evaluation

This paper presents the development of a miniaturized GaAs-based multi-functional monolithic microwave integrated circuit (MMIC) designed for X-Band synthetic aperture radar (SAR) applications. Utilizing the OMMIC D01PHS process with a 130 nm gate length, the MMIC integrates phase shifting, amplification, and attenuation functionalities using 98 numbers of microwave transistors in a compact size of $\mathrm{6 m m x} \mathbf{~} \mathrm{4.5 m m}$. In the transmit path, the MMIC incorporates a 6-bit digital phase shifter (DPS), a small signal amplifier and a driver amplifier, achieving a gain of $\gt15 \mathrm{~dB}$ with a phase error of ${\lt}6^{\circ} \mathrm{rms}$, providing precise beam steering capabilities. The receive path features small signal amplifiers (SSAs), a 6-bit DPS, and a 6-bit digital phase shifter (DPS), delivering a gain of $\gt12 \mathrm{~dB}$, with a phase error of ${\lt}6^{\circ} \mathrm{~ r m s ~ a n d ~ a ~ g a i n ~ e r r o r ~ o f ~}{\lt}0.5 \mathrm{~dB}$ rms. The paper details the design and simulation process, fabrication, and testing of the MMIC, highlighting its performance in comparison with prior studies. Compared to previous GaAs-based designs that employed separate MMICs for different functionalities, this work demonstrates superior miniaturization and integration, effectively reducing system complexity and size.