Design of linearity and efficiency improved Doherty PA using microstrip resonant cell

A Doherty power amplifier (DPA) using a novel front-coupled tapered microstrip resonant cell (TMRC) is proposed for linearity and efficiency improvement. The suppression of the second- and higher-order harmonics of the output of the main amplifier is achieved by incorporating the proposed TMRC. Moreover, the compensation of the phase delay and the impedance inversion are performed without any lumped element. The designed power amplifier has been simulated, and measurements of the fabricated power amplifier were made. The third-order inter-modulation distortion of the proposed DPA is reduced by 33 dB compared with the conventional ones.