Design of a High-Efficiency and High-Power Inverted Doherty Amplifier

Author

Ahn, Gunhyun ; Kim, Min-su ; Park, Hyun-chul ; Jung, Sung-chan ; Van, Ju-ho ; Cho, Hanjin ; Kwon, Sung-wook ; Jeong, Jong-Hyuk ; Lim, Kyung-hoon ; Kim, Jae Young ; Song, Sung Chan ; Park, Cheon-Seok ; Yang, Youngoo

Author_Institution

Sungkyunkwan Univ., Suwon

Volume

55

Issue

6

fYear

2007

fDate

6/1/2007 12:00:00 AM

Firstpage

1105

Lastpage

1111

Abstract

In this paper, we present a design method for a compact inverted Doherty power amplifier (IDPA), which has high-efficiency and high-power characteristics. An optimum load matching network and an additional offset line, after the matching network of the carrier amplifier, dynamically modulate the load impedance according to the input power drive, while the conventional Doherty power amplifier uses a quarter-wave line to do it. The operational principles and design guide are provided. For experimental verification, a 50-W Doherty amplifier was designed for the pi/4 differential quadrature phase-shift keying application at the 860-MHz band. The measured performance of the IDPA was compared with that of the balanced class-AB amplifier with the same output matching network. At an output power of 50 W, the IDPA performs with 3.16 dB better adjacent channel power ratio (-28 versus -24.84 dBc) and 6.15% higher power-added efficiency (59.02 versus 52.87%) than the class-AB amplifier does.

Keywords

UHF power amplifiers; differential phase shift keying; impedance matching; quadrature phase shift keying; IDPA; carrier amplifier; class-AB amplifier; differential quadrature phase-shift keying; frequency 860 MHz; inverted Doherty power amplifier; optimum load matching network; output matching network; power 50 W; quarter-wave line; Broadband amplifiers; Design methodology; Differential amplifiers; High power amplifiers; Impedance matching; Linearity; Microwave amplifiers; Power amplifiers; Power generation; Reflection; $pi/4$ differential quadrature phase-shift keying (DQPSK); Doherty power amplifier; inverted Doherty power amplifier (IDPA); load modulation; offset line;

fLanguage

English

Journal_Title

Microwave Theory and Techniques, IEEE Transactions on

Publisher

ieee

ISSN

0018-9480

Type

jour

DOI

10.1109/TMTT.2007.896807

Filename

4231316