A 360GHz Single-Element Multi-Mode Orbital Angular Momentum Cavity Antenna-Based Transmitter in 90nm SiGe BiCMOS

This paper introduces a fully integrated multi-mode orbital angular momentum (OAM) transmitter featuring a single-element on-chip antenna. Notably, it represents an on-chip transmitter capable of concurrently operating three orthogonal OAM modes (|loam| = 0, 1, 2). This allows different OAM modes to share a common phase center, facilitating the potential use of passive gain elements such as a lens or a reflector. The transmitter utilizes an oscillator at 120 GHz followed by a PIN diode frequency tripler to generate a 360 GHz signal. Implemented in GlobalFoundries 90 nm BiCMOS process, the radiator achieves a maximum radiated power of -8.1 dBm with 153 mW DC power dissipation, corresponding to a DC-THz efficiency of 0.1%. It also exhibits a wide frequency tuning range of 14.2%. This paper also presents measured OAM amplitude and phase distribution. It introduces a new method for measuring phase distribution without necessitating frequency and phase coherency.