A high‐linearity Doherty power amplifier using Metamaterial based on ferroelectric ceramics

Abstract

In this letter, a new Metameterial using ferroelectric ceramics is proposed to improve the linearity of the Doherty power amplifier (DPA). The conventional λ/4 transmission line is substituted by the periodic Metamaterial cell, which the impedance inversion can be performed by the proposed structure. Meanwhile, the second and higher order harmonics of the main amplifier is suppressed by this structure. In addition, the phase of Metamaterial can be changed to desired value by modifying the voltage of Barium Strontium Titanate (BST) because the loaded Metamaterial cell is based on BST. Accordingly, the AM‐PM distortion of the total DPA can be corrected by tuning the voltage of BST. Experiment results show that the third‐order inter‐modulation distortion (IMD3) of the proposed DPA can be reduced by 20 dB compared with the conventional DPA.