Linearization of a Multi-Band Multi-target Directional Modulation Transmitter Using Low-Complexity Crosstalk-Cancelled Digital Predistortion

This paper presents a multi-band multi-target (MBMT) directional modulation (DM) transmitter with low complexity crosstalk-cancelled digital predistortion (DPD). For a 16QAM 20 MHz bandwidth signal with -20 dB crosstalk, 8.0 dB PAPR, and 0.7 DM power efficiency (PE) level, the corresponding error vector magnitude (EVM) and the adjacent channel power ratio (ACPR) are 2.14% and -50 dBc after the proposed crosstalk-cancelled DPD. Compared with the 2×2 parallel Hammerstein (2×2 PH) DPD, the proposed DPD reduces the computational complexity without sacrificing the linearization performance. It only has 37.5% of the number of coefficients of the 2×2 PH model. To our best knowledge, it is the first time that the nonlinear distortion of the power amplifiers (PA) and the crosstalk between paths are simultaneously considered in an MBMT DM transmitter.