5.8 A 20W CMOS/LDMOS All-Digital Transmitter with Dynamic Retiming and Glitch-Free Phase Mapper, Achieving 68%/62% Peak Drain/System Efficiency

Base stations account for 73% of wireless-operators' energy consumption, mainly dominated by their analog-PA-based TXs [1]. All-digital transmitters (DTXs), leveraging custom $\text{low-V}_{\mathrm{T}}$ RF-power technologies [2], offer substantial energy savings by using switching operation and completely eliminating quiescent currents. In addition, DTXs enable extreme bandwidths since their circuit topology is frequency-agile up to the (power combining) output-matching network. To date, no high-power, high-efficiency DTX solutions have been reported that offer RF-power levels required for mMIMO base stations $(\mathrm{P}_{\text{avg}} > 3\mathrm{W})$, with the essential fine-gate segmentation and glitch-free operation to support wideband modulated signals. In this work, an 8-phase multi-phase (MP) DTX upconversion with dynamic retiming and a glitch-free phase-mapper operation is proposed (Fig. 5.8.1). The required output power, resolution, and sampling speed are achieved via a high-density flip-chip DTX approach with a high-speed DTX controller placed on a custom $\text{low-V}_{\mathrm{T}}$ LDMOS MMIC featuring power switch banks with in-finger gate segmentation (Fig. 5.8.1).