A 6–18-GHz Broadband Digital-Stepped Phase Shifter MMIC with Low In-Band Phase Error

This paper presents a 6–18-GHz Broadband 6-bit digital stepped phase shifter monolithic microwave integrated circuit (MMIC) with low in-band phase error. A reflective type phase shifter topology with phase variation compensation capacitor in the reflective loads is proposed to reduce in-band phase error. Improved unfolded Lange couplers are used to ensure the symmetry of the phase shifter. The broadband phase shifter has been fabricated in 0.25-μm GaAs pHEMT technology. Measurement results show that the phase shifter exhibits 6.8‒9.6-dB insertion loss over 6‒18-GHz. The 6-bit phase shifter achieves an RMS phase error of 3.7° and an RMS amplitude error of 0.46-dB over 6‒18-GHz. The proposed phase shifter, which is able to cover X- and Ku-bands, is a good candidate for broadband phased array applications.