An HBT Saturated Power Amplifier With Minimized Knee Effect for Envelope Tracking Operation

Author

Kyunghoon Moon ; Yunsung Cho ; Jooseung Kim ; Sangsu Jin ; Seokhyeon Kim ; Bumman Kim

Author_Institution

Dept. of Electr. Eng., Pohang Univ. of Sci. & Technol. (POSTECH), Pohang, South Korea

Volume

25

Issue

8

fYear

2015

fDate

Aug. 2015

Firstpage

544

Lastpage

546

Abstract

In this letter, a highly efficient saturated power amplifier (PA) based on a heterojunction bipolar transistor (HBT) is employed to maximize the efficiency of an envelope tracking (ET) PA. In this PA, output voltage waveform of the PA is shaped as a half-sinusoidal voltage waveform peaked by a second harmonic. The knee voltage effect is minimized in this voltage waveform due to the large fundamental voltage for a given supply voltage, which is very important for an ET PA with a low average supply voltage. Based on the saturated PA, the ET PA is tested at 1.85 GHz using a long term evolution signal. The ET PA delivers a power-added efficiency of 46.5%, an E- UTRAACLR of -33.4 dBc, and an error vector magnitude of 3.0% at an average output power of 27 dBm.

Keywords

Long Term Evolution; UHF power amplifiers; heterojunction bipolar transistors; HBT saturated power amplifier; efficiency 46.5 percent; envelope tracking operation; error vector magnitude; frequency 1.85 GHz; half-sinusoidal voltage waveform; heterojunction bipolar transistor; knee voltage effect; long term evolution signal; minimized knee effect; second harmonic; Capacitors; Harmonic analysis; Heterojunction bipolar transistors; Modulation; Moon; Power generation; Wireless communication; Efficiency; envelope tracking (ET); heterojunction bipolar transistor (HBT); long term evolution (LTE); power amplifier (PA); saturated amplifier;

fLanguage

English

Journal_Title

Microwave and Wireless Components Letters, IEEE

Publisher

ieee

ISSN

1531-1309

Type

jour

DOI

10.1109/LMWC.2015.2440771

Filename

7132795