High-Power Digital Transmitters for Wireless Infrastructure Applications (A Feasibility Study)

Fully digital transmitters (DTXs) have the potential of replacing analog-intensive transmitter (TX) line-ups in future massive multiple-input and multiple-output (mMIMO) systems since they hold the promise of higher system integration level and energy efficiency. DTX operation so far has been limited to low RF output powers. This article introduces a concept that enables high-power DTX operation. A DTX demonstrator targeting both high output power and high efficiency is realized as a proof of concept. It is based on a custom ${V_{T}}$ -shifted laterally-diffused MOS (LDMOS) technology, which is utilized to implement a segmented high-power output stage operated in class-BE. A low-voltage high-speed 40-nm CMOS controller drives the individual output stage segments at gigahertz rates. Measurements show the promising results for the proposed high-power DTX concept and provide valuable lessons for future DTX implementations.