Continuous Broadband GaAs and GaN MMIC Phase Shifters

• Published in: IEEE microwave and wireless components letters Vol. 32; no. 1; pp. 56 - 59
• Main Authors: Robinson, Megan, Danielson, Paige, Popovic, Zoya
• Format: Journal Article
• Language: English
• Published: IEEE 01.01.2022
• Subjects: Broadband; Broadband communication; Frequency measurement; GaAs; Gallium arsenide; GaN; monolithic microwave integrated circuit (MMIC); phase shifter; Phase shifters; Transistors; Transmission line measurements; Voltage measurement
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2021.3115411

We describe the design of two broadband monolithic microwave integrated circuit (MMIC) loaded-line reflective phase shifters and their performance over the 6-12-GHz band. Lange couplers with transistor-loaded transmission-line reactive loads provide variable phase shift through reverse-bias control. A GaAs phase shifter with four diode-connected transistors in each of the two reactive loads is designed with discrete inductors to provide an increasing phase shift with frequency. A GaN reflective phase shifter uses 14 transistors in each reactive load with a goal of increasing the phase shift across the band. Measurements show continuous phase shift from 40° to 70° with less than 6-dB insertion loss over the 6-10-GHz band and from 60° to 165° with less than 8-dB insertion loss across the 8-12-GHz band for the GaAs and GaN MMICs, respectively. The power performance of the MMICs is compared in terms of large-signal <inline-formula> <tex-math notation="LaTeX">S </tex-math></inline-formula>-parameters, harmonics, and IP3. The GaN phase shifter exhibits similar level of harmonic generation like the GaAs device at a 20-dB higher input power.