A 460MHz three-stage Doherty power amplifier with uneven power driving

This paper proposes a 450-470 MHz high efficiency three-stage Doherty power amplifier for IMT-Advanced system. The input matching and output matching are achieved by utilizing microstrip line and lumped-parameter components. Two 3 dB couplers are utilized to carry out uneven input power dividing so as to omit the two quarter-wave lines which are usually located before the main amplifier and the second peaking amplifier respectively. The simulation results show that the peak output power is 54.0 dBm, and the efficiency in the output power backed off 9.5 dB region is effectively improved. The gain flatness can maintain ±0.2 dB in the 450-470 MHz. Moreover, another two input dividing ratio are discussed, obtaining the power additional efficiency and power gain respectively.