Highly Linear 2-Stage Doherty Power Amplifier Using GaN MMIC

Abstract

A power amplifier (PA) for a femto-cell base station should be highly efficient, linear and small. The efficiency for amplification of a high peak-to-average power ratio (PAPR) signal was improved by designing an asymmetric Doherty PA (DPA). The linearity was improved by applying third-order inter-modulation (IM3) cancellation method. A small size is achieved by designing the DPA using GaN MMIC process. The implemented 2-stage DPA delivers a power-added efficiency (PAE) of 38.6% and a gain of 33.4 dB with an average power of 34.2 dBm for a 7.2 dB PAPR 10 MHz bandwidth LTE signal at 2.14 GHz. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ

2.6 GHz 4 watt GaN-HEMT two-stage power amplifier MMIC for LTE small-cell applications

“…It should transform the input impedance of the 2nd-stage to the load impedance of the 1st-stage [3], [4]. A shunt inductor includes a bond wire for smaller size and low loss since the bond wire is modeled as a high-Q inductor.…”

2.6 GHz GaN-HEMT Power Amplifier MMIC for LTE Small-Cell Applications

“…For the two-stage PA, the inter-stage matching network should be carefully designed [9][10][11]. The matching network transforms the input impedance of the 2nd-stage to the load impedance of the 1st-stage.…”

GaN‐HEMT asymmetric three‐way Doherty power amplifier using GPD

“…For the signals with high PAPR, Doherty power amplifiers have been popularly used to obtain high efficiency at an average output power level which is generally lower by a little more than the PAPR of the signal from the peak output power [1][2][3][4]. Since the general Doherty power amplifiers have another peak efficiency at the 6 dB output power back-off (OPBO), asymmetric Doherty power amplifiers (ADPAs), where the output power capacity of the peaking amplifier is larger than that of the carrier amplifier, have been proposed for a higher efficiency for larger OPBO [5][6][7][8][9][10][11][12][13]. ADPAs generally have an unequal power divider to asymmetrically distribute the input power to the carrier and peaking amplifiers.…”