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

摘要

This article presents a 2.4-4-GHz widehand 7-hit 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 05-mu m GaAs pHEMT process. The measured root-mean-square (rms) phase error of the proposed STPS is less than 3.1 degrees from 2.4 to 4 GHz and less than 1.5 degrees 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. IP1dB 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.