Linearity Improvement of HBT-Based Doherty Power Amplifiers Based on a Simple Analytical Model

A simple analytical model is proposed and shown to be effective in predicting the nonlinear behavior of single-ended amplifiers, as well as Doherty amplifiers implemented with GaAs heterojunction bipolar transistors (HBTs) for handset applications. The analytical model is based on linear and nonline...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on microwave theory and techniques 2006-12, Vol.54 (12), p.4479-4488
Main Authors: Yu Zhao, Metzger, A.G., Zampardi, P.J., Iwamoto, M., Asbeck, P.M.
Format: Article
Language:English
Subjects:
Amplifiers
Analytical models
Applied sciences
Circuit properties
Code division multiple access (CDMA)
Delay
Distortion measurement
Doherty amplifier
Electric, optical and optoelectronic circuits
Electronic circuits
Electronics
Exact sciences and technology
Gallium arsenide
Gallium arsenides
heterojunction bipolar transistor (HBT)
Heterojunction bipolar transistors
High power amplifiers
Linearity
Mathematical analysis
Mathematical models
Nonlinear equations
Power amplifiers
Receivers & amplifiers
Studies
Telephone sets
Tuning
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:A simple analytical model is proposed and shown to be effective in predicting the nonlinear behavior of single-ended amplifiers, as well as Doherty amplifiers implemented with GaAs heterojunction bipolar transistors (HBTs) for handset applications. The analytical model is based on linear and nonlinear components extracted from a vertical bipolar inter-company model for Skyworks Solutions Inc.'s InGaP/GaAs HBT devices. Equations derived from the model provide insights into effects of individual components on the gain and phase of both the single-ended and Doherty amplifiers. The model indicates that tuning the phase delay inserted in front of the auxiliary power amplifier (PA) within the Doherty can improve linearity at a high input power. The efficacy of the model is demonstrated by experimental results in which, for a Doherty PA with a tuned phase delay at the auxiliary PA side, the measured gain and phase agree with the simulation results. Furthermore, the third-order intermodulation distortion performance is improved as much as 8 dB when compared with a Doherty PA without phase delay tuning
ISSN:0018-9480
1557-9670
DOI:10.1109/TMTT.2006.883245