A Wideband 4-Port Gyrator-Based Circulator in 0.15μm GaN MMIC

This paper presents a wideband circulator investigating the influence of highly linear III - V switches on power handling capability. A four-port differential gyrator-based architecture is implemented using 0.15μm GaN HEMT switch devices. The fabricated circulator prototype exhibits a symmetrical transmission/isolation response across all four ports thanks to its balanced nature. The modulation frequency of 1.52GHz results in an operation regime of 0.1-4GHz (~200% fractional BW). Measurements indicate that the circulator offers a transmission loss between 1.92-5dB while achieving a > 15dB port-to-port isolation. It provides an 11dBm IP1dB and 24dBm IIP3 while occupying a die area of 3.75 × 6.25mm
²
including delay lines. The measured IIP3 is 5.5dB higher, while the BW is 2 × better than prior GaN circulators.