A DC-18 GHz 6-Bit GaAs Attenuator With High Attenuation Accuracy

In response to the demand for ultra-wideband digitally controlled attenuators in the field of microwave communication, this study fabricated a digital-driven 6-bit attenuator chip operating in the DC~18 GHz range using 0.15 μm GaAs pHEMT technology. The attenuator consists of six cascaded basic attenuation units, each employing appropriate circuit topology to achieve objectives such as low insertion loss, high attenuation accuracy, low additional phase shift, and miniaturization. Additionally, our study introduced a phase compensation structure on the traditional attenuator topology to further reduce the additional phase shift of the attenuator. Simulation results of the chip demonstrate a dynamic attenuation range from 0.5 dB to 31.5 dB, with insertion loss less than 4.3 dB, input and output return loss exceeding -12 dB, root mean square attenuation accuracy (64 states) less than 0.3 dB, and additional phase shift of all attenuation states less than 6°. Furthermore, the dimensions of the chip are 2.6 mm × 0.9 mm × 0.1 mm.