隨著5G通訊系統的發展，訊號的傳輸頻帶已發展至毫米波頻帶。但是訊號經由毫米波頻帶傳輸時，其功率衰減非常嚴重，所以相位陣列成為5G毫米波頻帶通訊系統傳送端不可或缺的要件，以利用波束成形克服毫米波頻帶訊號功率嚴重衰減的情形。然而，相位陣列中之功率放大器具有非線性效應會造成頻譜增生，導致其他頻帶的訊號受到干擾，因此本論文根據文獻中間接學習架構發展出數位預失真演算法，補償功率放大器陣列之非線性效應。但是，由於硬體的限制，功率放大器陣列並無回授的機制將各個功率放大器之輸出訊號回授以計算預失真器係數，本論文根據文獻提出的方法，以傳送端觀察天線之接收訊號，當回授訊號以訓練預失真器係數。因為傳送端與觀察天線可能存在載波頻率不同步的現象，所以本論文參考文獻中的載波頻率偏移估計與補償的方法，使傳送端與觀察天線之載波頻率得以同步，以降低預失真係數估計的誤差與難度。本論文以工研院研發的毫米波相位陣列模組進行實測，實測結果顯示，數位預失真演算法可有效改善功率放大器陣列的線性度，而且，每個方向之頻帶外輻射均有降低。

With the development of 5G communication systems, the millimeter-wave (mmWave) band has been widely used. However, the transmission over this band suffers from severe path losses. The phased array has become an indispensable element of the 5G mmWave systems since beamforming is typically used to overcome the path losses. However, the nonlinear effect of the power amplifier array of the phased array leads to spectral regrowth and causes interference to signals in adjacent bands. In the thesis, we develop the digital predistortion algorithm based on the indirect learning architecture in the literature to compensate for the nonlinear effect of the power amplifier array. Due to hardware limitations, the power amplifier array does not have a feedback mechanism to feed back the output signal of each power amplifier for the use of calculating the DPD coefficients. In the thesis, based on the structure proposed in the literature, we use the observation antenna (OA) that is placed in the direction of the steering angle of the array to receive the transmitted signal over the air, and use OA's output signal to arrive at the DPD coefficients. Because the OA and the transmitter may not be perfectly synchronized in frequency, the carrier frequency offset needs to be estimated and compensated before the DPD coefficients ae computed. To evaluate the effectiveness of the linearization algorithm, we use the mmWave phased array module developed by the Industrial Technology Research Institute to conduct the measurements. The experimental results show that the linearization algorithm significantly improves the linearity of the power amplifier array and reduces the out of band radiation in various directions.

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