Millimeter-wave (mmWave) technology has been extensively studied for indoor short-range communications. In such fixed network applications, the emerging FTTR architecture allows mmWave technology to be well cascaded with in-room optical network terminals, supporting high-speed communication at rates over tens of Gbit/s. In this Fiber-to-the-Room (FTTR)-mmWave system, the severe signal attenuation over distance and high penetration loss through room walls are no longer bottlenecks for practical mmWave deployment. Instead, these properties create high spatial isolation, which prevents mutual interference between data streams and ensures information security. This paper surveys the promising integration of FTTR and mmWave access for next-generation indoor high-speed communications, with a particular focus on the Ultra-Converged Access Network (U-CAN) architecture. It is structured in two main parts: it first traces this new FTTR-mmWave architecture from the perspective of Wi-Fi and mmWave communication evolution, and then focuses specifically on the development of key mmWave chipsets for FTTR-mmWave Wi-Fi applications. This work aims to provide a comprehensive reference for researchers working toward immersive, untethered indoor wireless experiences for users.

In view of the existing design challenges for Terahertz (THz) power amplifiers (PAs), the common design methods and the efforts of the State Key Laboratory of Millimeter Wave, Southeast University, China in the development of silicon-based THz PAs, mainly including silicon-based PAs with operating frequencies covering 100–300 GHz, are summarized in this paper. Particularly, we design an LC-balun-based two-stage differential cascode PA with a center frequency of 150 GHz and an output power of 14 dBm. Based on a Marchand balun, we report a 220 GHz three-stage differential cascode PA with a saturated output power of 9.5 dBm. To further increase the output power of THz PA, based on a four-way differential power combining technique, we report a 211–263 GHz dual-LC-tank-based broadband PA with a recorded 14.7 dBm Psat and 16.4 dB peak gain. All the above circuits are designed in a standard 130 nm silicon germanium (SiGe) BiCMOS process.

A novel envelope design for an envelope tracking (ET) power amplifier (PA) based on its derivatives is proposed, which can trade well off between bandwidth reduction and tracking accuracy. This paper theoretically analyzes how to choose an envelope design that can track the original envelope closely and reduce its bandwidth, and then demonstrates an example to validate this idea. The generalized memory polynomial (GMP) model is applied to compensate for the nonlinearity of ET PA with the proposed envelope design. Experiments are carried out on an ET system that is operated with the center frequency of 3.5 GHz and excited by a 20 MHz LTE signal, which show that the proposed envelope design can make a good trade-off between envelope bandwidth and efficiency, and satisfactory linearization performance can be realized.