The Efficiency and Power Utilization of Current-Scaling Digital Transmitters

The RF performance of current-scaling digital transmitters (DTX) with polar, unsigned Cartesian, signed Cartesian, and multiphase architectures have been compared regarding power utilization of their output-stage switch banks and drain efficiency. The analysis includes various switch bank operation modes, such as switch bank sharing, segment activation interleaving, and their activation times (RF duty cycle of the segments). Current-scaling DTXs can be made compatible with high-power operations while offering high system efficiency and RF bandwidth. The average efficiency using Doherty power back-off efficiency enhancement is analyzed, and a comparison of the different proposed DTX implementations is presented.