Linearization of symmetrical and asymmetrical two-way Doherty amplifier

Abstract

The linearization effects on two-way Doherty amplifiers are presented in this paper. Symmetrical Doherty amplifier with the additional circuit for linearization has been realized and measurements of the linearization influence on the third- and fifth-order intermodulation products have been carried out. Asymmetrical Doherty amplifier has been designed and effects of the applied linearization technique have been considered through the simulation process. The linearization approach uses the fundamental signals? second harmonics and fourth-order nonlinear signals that are extracted at the output of the peaking cell, adjusted in amplitude and phase and injected at the input and output of the carrier cell in Doherty amplifier. [Projekat Ministarstva nauke Republike Srbije, br. TR-32052]

Comment on “linearization of power amplifiers by second harmonics and fourth‐order nonlinear signals” by A. Atanaskovic, N. Males‐Ilic, and B. Milovanovic

“…The great majority of the results presented in are essentially reformulated results from previously published papers and . Besides, papers and are not cited in , and paper is not cited in the newer paper .…”

“…Besides, papers and are not cited in , and paper is not cited in the newer paper . This points to the apparent intention of the authors to reuse the same results, concealing important facts from the reviewers in newer paper and finally in .…”

“…Parts of the paper that are re‐used from the previous papers are: Figure 2 from is the same as Figure 4in and Figure 3in Figure 6 from is the same as Figure 2in and Figure 2in Figure 5 from is mostly the same as Figure 1in (Figure 1in has an optional attenuator because of the asymmetry) and completely the same as Figure 1in Figure 7 from is the same as Figure 7b in Figure 8 from is the same as Figure 8b in Figure 9 from is the same as Figure 9in and Figure 8in …”

Linearization of broadband two-way microstrip Doherty amplifier

“…It comprises M/A-COM PIN diode variable attenuator MA4VAT2007-1061T, two Mini-Circuits 180° voltage variable phase shifters JSPHS-23+ to provide phase shift of 360° and Skyworks high linear 2W power amplifier SKY65120. This linearization circuit, which was already used in experiments performed for the linearization of narrowband amplifiers, [10], [11] satisfies the requirements for broadband applications.…”

“…We applied the approach where the IM2 and IM4 signals are injected together with the fundamental signals into the carrier amplifier input and fed at its output [9]. Additionally, the influence of IM2 and IM4 signals on Doherty amplifier linearity was verified experimentally on a standard symmetrical and asymmetrical two-way Doherty amplifier [9], [10] and [11].…”