A 2–6 GHz Continuous Tuned Phase Shifter MMIC Achieving 0.9 dB RMS Amplitude Error

Abstract

A novel structure to design a fully integrated wideband 360° analog phase shifter (PS) from 2 to 6 GHz is presented in this letter. This novel structure uses magnetically coupled all-pass networks (MCAPNs) cascaded with different center frequencies to construct a relatively flat broadband phase response. Furthermore, to solve the problem that MCAPN is hard to realize at the chip level when high frequencies, a tunable low-pass network (LPN) is introduced to compensate for the high-frequency band phase response. Unlike the existing methods, the new structure makes the bandwidth of PS more comprehensive, and the in-band flatness is better. For verification, a wideband monolithic microwave integrated circuit (MMIC) analog PS was designed and fabricated using a 2-μm gallium arsenide (GaAs) based heterojunction bipolar transistor (HBT) process. Measurement results show that the fabricated analog PS has a low average insertion loss of 6.0 ± 0.56 dB, low root mean square (rms) amplitude error of <0.9 dB, and low rms phase error of <9° from 2–6 GHz. The proposed analog PS has the most significant bandwidth compared with other reported passive phase shifters maintaining flat phase shift characteristics.