Linearization of Terahertz Transmitter Based on LowSampling Rate DAC and ADC br

TeraHertz (THz) with high frequency and large bandwidth is an advantageous potential wirelessspectrum resource in Sixth Generation (6G) mobile communication. However, the nonlinear distortion of THzdevices limits the power conversion efficiency and the communication transmission distance. If traditionalDigital Pre-Distortion (DPD) technology is used for non-linear correction, the sampling rate of the Digital-to-Analog Converter (DAC) and Analog-to-Digital Converter (ADC) is usually required to reach 5 times thesignal bandwidth, which is difficult to apply to the THz frequency band. Therefore, in this paper, a digitalcorrection method is proposed to correct the nonlinearity of the THz transmitter using the low-rate DAC andADC. This method is mainly divided into three steps: Firstly, the observation data obtained by the lowsampling rate ADC is used, and the high sampling rate observation signal with limited bandwidth is recoveredby up-sampling. At this time, the signal sampling rate is 5 times the signal bandwidth, which can effectivelycharacterize the 5th order nonlinear distortion; Then the DPD model with limited bandwidth is established to extract the DPD correction coefficient; Finally, the corrected signal is down-sampled to the DAC to correct thenonlinear distortion of the transmitter channel. The simulation results show that when DAC and ADC work atthe sampling rate of 1.25 times the baseband signal rate, for a 64-QAM modulated signal, the Error VectorMagnitude (EVM) can be reduced from 8.46% to 2.27%. Therefore, modulation schemes with higher spectrumefficiency can be adopted in THz communications.