A novel 6.5-13.5GHz 6-bit digital phase shifter with ultra low RMS phase error in 0.25-µm GaAs p-HEMT technology

Abstract

This letter presents a broadband, high-precision bidirectional passive 6-bit digital phase shifter (DPS) designed for phased array systems. We propose three novel structures: the dual modified magnetically coupled all pass network (DMMCAPN) for small phase shifts, the modified high pass network/modified magnetically coupled all pass network (MHPN/MMCAPN) for medium phase shifts, and the Lange/modified transmission line network (L/MTLN) for large phase shifts. It shows a phase shift range of 360° with a step of 5.625°. Measurements in the 6.5-13.5GHz range indicate that the root-mean-square (RMS) phase and amplitude errors for the 64 states are within 1.8° and 0.75dB, respectively. Additionally, the average insertion loss is (-12.2±0.5)dB and the input 1dB compression point (IP1dB) is 29dBm at IF 10GHz. To the best of our knowledge, this letter presents an exceptionally high degree of phase shift accuracy across the broad bandwidth, outperforming other GaAs passive digital phase shifters. Furthermore, it showcases superior linearity when compared to silicon-based passive digital phase shifters.