A Generic Theory for Design of Efficient Three-stage Doherty Power Amplifiers
Artikel i vetenskaplig tidskrift, 2021

An analytical load-pull based design methodology for three-stage Doherty power amplifiers (PAs) is presented and demonstrated. A compact output combiner network, together with the input phase delays, is derived directly from transistor load-pull data and the design requirements. The technique opens up a new design space for three-stage Doherty PAs with reconfigurable high-efficiency power back-off levels. The method is designed to enable a high transistor power utilization by maintaining full voltage and current swings of the main and auxiliary amplifier cells. Therefore, a wide efficiency enhancement range can be achieved also with symmetrical devices. As a proof of concept, a 2.14-GHz 30-W three-stage Doherty PA with identical GaN HEMT active devices is designed, fabricated and characterized. The prototype PA is able to linearly reproduce 20-MHz long-term evolution signals with 8.5- and 11.5-dB peak-to-average power-ratio (PAPR), providing average efficiencies of 56.6% and 46.8% at an average output power level of 36.8 and 33.8 dBm, respectively. Moreover, an average efficiency as high as 54.5% and an average output power of 36.3 dBm have been measured at an adjacent power leakage ratio of -45.7 dBc for a 100-MHz signal with 8.5-dB of PAPR, after applying digital pre-distortion linearization.

energy efficiency

high peak-to-average power ratio (PAPR)

gallium nitride (GaN)

Doherty power amplifiers

Combiner synthesis

three-stage symmetrical devices


Han Zhou

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik, Mikrovågselektronik

Jose-Ramon Perez-Cisneros

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

Sara Hesami

Ericsson AB

Koen Buisman

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

University of Surrey

Christian Fager

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

IEEE Transactions on Microwave Theory and Techniques

0018-9480 (ISSN)

Vol. In press






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