Design of a broadband three-way sequential Doherty power amplifier for modern wireless communications

Toward a More Generalized Doherty Power Amplifier Design for Broadband Operation

“…Since the output current of the Auxiliary PA is zero, the impedance ZA is infinity, (30). Subsequently, TL2 and TL3 will transform this impedance into an open circuit at the center frequency, and provide good isolation over a wide bandwidth.…”

“…Moreover, other techniques have been proposed to design wideband DPAs such as digital DPA [5], three-way sequential DPA [30], and DPA with an output combiner comprised of a branch-line coupler [31].…”

Bandwidth Enhancement of Three-Stage Doherty Power Amplifier Using Symmetric Devices

“…This paper proposes another choice of topology, where symmetrical devices are used such that the current ratio and are less than 1, implying that the auxiliary PAs will provide lesser current than the main PA at saturation, while using devices of the same size. In this manner, one can avoid rigorous exercise of stabilization of network, implementation of input and output matching networks for each device, as in a configuration using asymmetric devices [14], [15]. A single PA replicates the main PA as well as auxiliary PAs in a symmetric DPA configuration.…”

“…Thus, the multi-stage architecture extends the dynamic range of the DPA in terms of high average efficiency. The multi-stage DPA architectures proposed in [12]- [15] require asymmetric devices with different device peripheries. The required back-off points are set by proper selection of size ratio among these devices.…”

“…Therefore, in order to support the upcoming high bandwidth requirements, while providing a ubiquitous PA, this paper extends the three-stage DPA design based on symmetric devices, as reported in [11], for broadband application. To the best of authors' knowledge, the earlier broadband three-stage DPAs utilize asymmetric devices [14], [15], whereas the proposed work is the first attempt to design a three-stage DPA using symmetric devices with a systematic bandwidth enhancement scheme. This paper is organized as follows.…”