C X Ku K-Band Precision Compact 6-Bit Digital Attenuator with Logic Control Circuits

This paper introduces a 6-bit digital step attenuator (DSA) designed for C/X/Ku/K bands, utilizing a range of enhanced attenuation cells to achieve wide bandwidth, stable amplitude and phase variations, and a compact design. The paper provides a theoretical analysis of the improved T-type, π-type, and switched-path topologies, which are applied to different attenuation values to optimize the attenuator's performance. To simplify the design and enhance the stability of the overall radar system, the logic control circuit is integrated directly into the DSA chip. The proposed attenuator is implemented in 0.15µm GaAs technology and offers a maximum attenuation range of 31.5 dB with 0.5 dB steps. Measurement results show that the DSA achieves an RMS attenuation error of less than 0.15 dB and an RMS phase error of less than 3° over the 4–24 GHz range. The insertion loss (IL) is between 4.3–4.5 dB, and the DSA occupies an area of 1.5 mm × 0.4 mm. Thanks to the enhanced attenuation cells and the strong radiation resistance and power handling capabilities of GaAs technology, this DSA is well-suited for spaceborne radar systems.