A wideband CMOS power amplifier for 77 GHz automobile radar and 94 GHz image radar systems

This article reports a wideband four-way CMOS power amplifier for 77 GHz automobile radar and 94 GHz image radar systems in 90 nm CMOS technology. The PA comprises a two-stage common-source (CS) cascaded input stage with wideband pi-match input, inter-stage, and output networks, followed by a two-way cascode gain stage using miniature zero-degree two-way divider and combiner, and a four-way CS output stage using miniature zero-degree four-way divider and combiner. At each branch's input terminal (i.e., drain terminal of the parallel CS output stage), the miniature zero-degree four-way combiner can convert the serial RL load to the optimal load impedance [corresponds to the optimal output power (P-out) and power-added efficiency (PAE)] of the output stage transistors. The PA achieves power gain of 23.9, 24.1, and 20.4 dB, respectively, at 71, 77, and 94 GHz. In addition, the PA achieves P-out of 12.3, 12.2, and 9.7 dBm, respectively, at 71, 77, and 94 GHz. The maximal PAE is 18.2%, 17.3%, and 8.9%, respectively, at 71, 77, and 94 GHz. The excellent performance of the CMOS PA indicates that it is suitable for both 77 GHz automobile radar and 94 GHz image radar transceivers.