A Wideband Energy-Efficient Multi-Mode CMOS Digital Transmitter

This article presents a wideband, energy-efficient digital transmitter (DTX) suitable for multi-mode/multi-band wireless communication applications. It features various operation modes comprising Cartesian (Modes-1/-2) and multi-phase (Modes-3/-4) configurations utilizing LO clocks with different duty cycle in the interleaving/non-interleaving configurations. The compromises polar by mapping $I/Q$ signals into two non-orthogonal basis vectors 45° relative phase difference 3-bit selector scheme. are extensively analyzed compared. Fabricated 40-nm CMOS process an off-chip matching network, proposed DTX occupies core area of 0.72 mm2 delivers 23.18-dBm RF peak power at 2.1 GHz from 0.95-V supply voltage drain/system efficiencies 66.26%/52.59%, respectively. Utilizing simple memory-less pre-distortion (DPD) 160-MHz four-channel 64-quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM) signal, average notation="LaTeX">$P _{\text {Out}}$ 13.5/11.4/7.7/9.4 dBm, achieving adjacent channel (power) ratio (ACL(P)R) better than −42/−40/−40/−38 dBc error vector magnitude (EVM) −36/−34/−34/−32 dB, operating Modes-1/-2/-3/-4, While transmitting 200-MHz single-channel 256 (1024)-QAM OFDM signal 2.4 Modes-1/-4, delivered output is 14.11/9.29 (12.23/7.32) dBm drain system 33.17%/26.3% (23.82%/22.83%) 24.81%/22.85% (19.34%/18.81%), while ACLR EVM −42/−41 (−43/−43) −34.6/−33.1 (−33.5/−33.9)