A 2.4–4-GHz Wideband 7-Bit Phase Shifter With Low RMS Phase/Amplitude Error in 0.5-μm GaAs Technology

This article presents a 2.4–4-GHz wideband 7-bit switch-type phase shifter (STPS) with a switch driver. Three switch-type phase shifting topologies are employed for the design of the phase shifter (PS), including the switched
$L/C$
structure, T-type structure, and high-/low-pass network. For minimizing the phase and amplitude deviations, an improved T-type structure with a switched filter structure has been proposed to boost the performance of the PS. Besides, a phase compensation cell also has been adapted to further decrease the phase error of the STPS. Based on the topology choice of each cell and the amplitude compensation among cells, a systematic design method is developed to extend the bandwidth of the PS. The proposed 7-bit STPS was implemented in the 0.5-
$\mu \text{m}$
GaAs pHEMT process. The measured root-mean-square (rms) phase error of the proposed STPS is less than 3.1° from 2.4 to 4 GHz and less than 1.5° at 2.8–3.7 GHz. The average insertion loss (IL) is 4.5–4.9 dB with an rms amplitude error of less than 0.34 dB. IP
_{1 dB}
is about 30 dBm. To the best of our knowledge, this PS achieves the highest resolution and the lowest rms amplitude error among the published GaAs/GaN PSs over a similar frequency band. The IL, bandwidth, and rms phase error of the proposed PS also show good performance.