Optimization design of a broadband three-stage Doherty power amplifier

This paper proposes a three-stage broadband Doherty power amplifier with an extended efficiency range for TD-LTE application at 1.9-2.0GHZ. In this design, we use LDMOS devices with a power ratio of 1:1:1, The radial stubs are utilized in the dc bias network to increase the bandwidth. The power added efficiency of the proposed three-stage Doherty PA has been maintained 47% at an average output power of 46 dBm, which is 9 dB backed-off from the peak output power of 55 dBm. The simulation results clearly show that the three-stage Doherty is an efficient architecture among the various Doherty PAs, especially for a high peak to average power ratio (PAPR) signal.