A Wideband 6-bit Phase Shifter with Low Insertion Loss

Based on the 0.25-μm GaAs pseudomorphic high electron mobility transistor (pHEMT) process, a 6-18 GHz low insertion loss 6-bit phase shifter chip with digital driver was developed. In order to achieve low insertion loss, wide-bandwidth, and high phase-shifting accuracy, different structures are used: 5.625°, 11.25°, and 22.5° phase-shifting bits with a bridge T-type structure; 45° and 90° phase-shifting bits with a switched high-low pass filter structure; and 180° phase-shifting with a Lange coupler. The driver unit employs a direct-coupled field-effect transistor logic (DCFL) structure. Simulation results show that the insertion loss of the phase shifter is less than 9 dB, the root-mean-square error (RMS) of the phase shifter is less than 8°, the amplitude variation is ±1 dB, and the input-output return loss is less than -10 dB in the operating frequency band of 6-18 GHz. The chip size is 2.9 mm × 1.87 mm, and it is characterized by wideband and low insertion loss.