A Wideband Compact 6-bit Digital Step Attenuator

This paper proposes a wideband digital step attenuator (DSA) in 6 bits. To provide broadband, steady amplitude, stable phase variation, and a compact attenuator area, some improved attenuation cells are employed in the design. Firstly, the enhanced T-type and π-type attenuation cells are analyzed theoretically. Based on the analysis, the best performance can be obtained by using different improved attenuation cells to different attenuation values rationally. Eventually, the devised attenuator is manufactured in 0.15 μm GaAs process. The designed DSA demonstrates a root-mean-square (rms) attenuation error below 0.28 dB and a rms phase error below 6°, at 4-22 GHz. The DSA insertion loss (IL) is 3.4-4.1 dB and the area is 0.4 mm × 1.5 mm. Thanks to the good performances of the attenuator and the strong resistance to radiation of the GaAs process, the designed DSA is appropriate for satellite systems.