A Differential SiGe HBT Doherty Power Amplifier for Automotive Radar at 79 GHz

In this paper, a differential Doherty power amplifier for automotive applications in a 130nm SiGe BiCMOS technology, featuring ft/fmax of 470/650 GHz, is presented. The amplifier achieves a measured, peak power added efficiency of 11.6% with 17.0dBm saturated output power at a frequency of 79GHz. In the 6dB power back-off, the proposed amplifier offers a power added efficiency of 6.1%. For comparison, a reference Class-A amplifier has been designed that achieves an output power of 7.2dBm at the 6dB power back-off with a power added efficiency of 1.8%. Compared to other state-of-the-art Doherty approaches, the proposed architecture first time proves the traditional transmission line-based impedance inversion in the automotive frequency range from 76GHz to 81GHz.