An Outphasing All-Digital Transmitter

All digital transmitter with outphasing (OADT) has been identified as a suitable candidate for massive MIMO systems. However, with the existing phase modulation methods, the OADT performance is subject to the phase resolution (PR). When the PR is limited, the OADT performance degrades vastly. To address this issue, a novel OADT with mapping-based PWM (MPWM) method is proposed, which is called the MPWM-OADT. The phase modulation is realized by a LUT. The architecture of MPWM-OADT and the components are expounded. By the noise analysis model, the optimizations of adjacent channel leakage ratio (ACLR) and coding efficiency (CE) are discussed. Simulation and experiment results show that the MPWM-OADT has good performance and it is free of PR limitation. Under the same condition, the MPWM-OADT outperforms the OADTs with other phase modulation methods in ACLR and Error Vector Magnitude (EVM). Meanwhile the indicators keep stable when the PR decreases.