A Silicon Photonic-CMOS Transceiver for 5G Radio-Over-Fiber Communications: An emerging highly-integrated heterogeneous solution for future high-speed wireless networks

To provide reliable, low latency, high data rate connections for 5G mobile networks and beyond, millimeter-wave spectrum is adopted due to its wide available bandwidth. For the mobile fronthauling, a seamless combination of optical fiber and wireless link is an attractive solution. In this article, a millimeter-wave-over-fiber system is demonstrated based on an analog radio-over-fiber architecture that accommodates a variety of modulation formats for different wireless applications and, hence, can be practically transparent to the wireless signal formats. This millimeter-wave-over-fiber heterogeneous system is an efficient remote antenna prototype with a small form factor supporting future wireless networks. The core of the system features high-speed optical components, fiber array, wireless electronic front-end ICs, and patch antenna array. A high-speed Ge photodetector and a SiGe electro-absorption modulator are bonded to a CMOS chip consisting of a transimpedance amplifier, a power amplifier, a low-noise amplifier, and a modulator driver. Considering 28-GHz 16-QAM OFDM signals, the opto-electronic transmitter and receiver achieve an error vector magnitude of 10% and 7.5%, respectively, satisfying 5G requirements.