Summary
International Technical Conference on Circuits/Systems, Computers and Communications
2008
Session Number:P1
Session:
Number:P1-15
Linearity-Optimized 3.5 GHz GaN HEMT Doherty Amplifier
Yong-Sub Lee, Mun-Woo Lee, Yoon-Ha Jeong,
pp.-
Publication Date:2008/7/7
Online ISSN:2188-5079
Summary:
This paper reports the linearity optimization of GaN HEMT Doherty amplifier for 3.5 GHz WiMAX applications. For the linearity optimization of the Doherty amplifier, not only gate biases but also shunt capacitors in output matching circuits of the carrier and peaking cells are controlled. For experimental verifications, a Doherty amplifier is designed and implemented using Cree CGH40010 with 10-W peak envelope power (PEP) and tested using a 1-carrier WCDMA and WiMAX signals. The Doherty amplifier is optimized for a WiMAX signal at an output power of 33 dBm, which is a 9.5-dB back-off power from the saturation power of 42.5 dBm. From the measured results, the relative constellation error (RCE) is {±4.2 dB with the drain efficiency of 27.8%, compared to the class-AB power amplifier with the RCE and drain efficiency of -24.3 dB and 16.3 %.