Microelectronics By

i Currently the Doherty Power Amplifier (DPA) is replacing the traditional Class B amplifier in base-station and broadcast applications, as such becoming the preferred choice of industry due to its simplicity and high efficiency performance. In spite of its success, so far practical DPA implementations can provide only a very limited RF bandwidth, which tends to narrow down even more at higher power levels. This narrowband behavior of the DPA is mostly caused by the use of traditional operating classes for the active devices and bandwidth restrictions related to use of a conventional impedance inverter. In this work, the bandwidth of different DPA topologies has been analyzed, followed by a discussion of recent techniques that can help to improve the DPA bandwidth. To overcome the remaining bandwidth limitations in a DPA design, a novel differential configuration was proposed. In this approach, transmission line based baluns are used to implement the desired wideband 2nd harmonic terminations of the active devices