A wideband quasi-asymmetric Doherty power amplifier with a two-section matching-phase difference compensator network des
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A wideband quasi-asymmetric Doherty power amplifier with a twosection matching-phase difference compensator network design using GaAs technology Seyedehmarzieh Rouhani1 • Ahmad Ghanaatian1 • Adib Abrishamifar1
•
Majid Tayarani1
Received: 8 August 2019 / Revised: 9 September 2020 / Accepted: 6 October 2020 Ó Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this paper, a quasi-asymmetric Doherty power amplifier (PA) is designed without load modulation using the GaAs 0.25 lm pHEMT technology to reach an enlarged output power back-off (OPBO) with circuitry solutions in order to overcome technology restrictions. To prevent power leakage in auxiliary PA (PAaux) due to its extremely low off-state impedance (Zoff), a Wilkinson power combiner is added to the output. Moreover, an input asymmetric power divider is designed to guarantee that no considerable power is delivered to the main PA (PAmain) in the high-power region to make it saturated. A two-section matching network is proposed for PAmain, which simultaneously compensates for phase differences of the main and auxiliary amplification paths. To control the significant impedance variation of PAaux versus sweeping power and the different impedance trajectories of the main and auxiliary amplification paths, the bias and dimension selection of PAaux are analyzed to reach the desired output power profile versus input power. These methods overcome impedance variations and linearity degradation. To achieve the aimed 10% fractional bandwidth, appropriate low-quality LC-networks are selected as matching networks. The simulation results indicate the utility of the proposed structure for microwave link applications. Continuous-wave simulations imply that the proposed PA has a 33 dBm maximum output power and a 13.5 dB power gain with less than 1 dB power gain compression in the desired frequency range (7.6–8.4 GHz). The drain efficiency of 30% at the highest input power, minimum of second and third harmonic powers of - 140 dBm and - 130 dBm, respectively, and OPBO of 7.5 dB are also obtained. Keywords Asymmetric Back-off Doherty power amplifier MMIC PAPR Wideband
1 Introduction To overcome the issue of efficiency roll-off in basic PAs, a Doherty power amplifier (DPA) was introduced [1]. Due to the potency of DPA for performance optimization at output
& Adib Abrishamifar [email protected] Seyedehmarzieh Rouhani [email protected] Ahmad Ghanaatian [email protected] Majid Tayarani [email protected] 1
School of Electrical Engineering, Iran University of Science and Technology, Tehran, Iran
power as well as its bandwidth and efficiency scopes, numerous researches have been conducted on its various structures [2–14]. Many structural modifications in the scientific research trend of DPA design are done by changing the concept of the conventional DPA [12–25]. One such change leads to more contribution of PAaux to output power compared to PAmain, and this DPA is called asymmetric DPA (ADPA) [2]. This PA provides a
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