Integration of Self-Biased Circulators on GaN/SiC for Ka-band RF application

Monolithic microwave integrated circuit (MMIC) transit/receive (T/R) modules are widely used in radar and communication systems. The transmitter and receiver usually share the same antenna either by a high frequency switch or a magnetic circulator. Switches can be monolithically integrated in the same chip with the power amplifier (PA) and low noise amplifier (LNA) circuits. But signals are processed by the PA and LNA alternately. Circulator has an advantage over switches as it allows simultaneous signal transmission and reception. However, conventional circulators use ferrites which need external permanent magnets to bias ferrites [1]. This makes circulators bulky and limits or even prohibits monolithic implementation in T /R modules. In a self-biased (SB) circulator, ferrite possesses remnant magnetization and no external magnetic field is needed [2]-[4]. In this report, we have demonstrated the first monolithically integrated Ka-band SB circulator on a GaN/SiC wafer leveraging Qorvo's GaN technology and self-biased ferrite materials from Metamagnetics.