Modeling and Digital Predistortion of Class-D Outphasing RF Power Amplifiers

This paper presents a direct model structure for describing class-D outphasing power amplifiers (PAs) and a method for digitally predistorting these amplifiers. The direct model structure is based on modeling differences in gain and delay, nonlinear interactions between the two paths, and difference...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on microwave theory and techniques 2012-06, Vol.60 (6), p.1907-1915
Main Authors: Landin, P. N., Fritzin, J., Van Moer, W., Isaksson, M., Alvandpour, A.
Format: Article
Language:English
Subjects:
Amplification
Amplifiers
Baseband
Behavioral modeling
Delay
Digital
digital predistortion
Gain
LINC
Mathematical models
Nonlinear distortion
Numerical models
outphasing amplifier
Phase distortion
Phases
Polynomials
Power amplifiers
power amplifiers (PAs)
Predistortion
TECHNOLOGY
TEKNIKVETENSKAP
Voltage
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:This paper presents a direct model structure for describing class-D outphasing power amplifiers (PAs) and a method for digitally predistorting these amplifiers. The direct model structure is based on modeling differences in gain and delay, nonlinear interactions between the two paths, and differences in the amplifier behavior. The digital predistortion method is designed to operate only on the input signals' phases, to correct for both amplitude and phase mismatches. This eliminates the need for additional voltage supplies to compensate for gain mismatch. Model and predistortion performance are evaluated on a 32-dBm peak-output-power class-D outphasing PA in CMOS with on-chip transformers. The excitation signal is a 5-MHz downlink WCDMA signal with peak-to-average power ratio of 9.5 dB. Using the proposed digital predistorter, the 5-MHz adjacent channel leakage power ratio (ACLR) was improved by 13.5 dB, from -32.1 to -45.6 dBc. The 10-MHz ACLR was improved by 6.4 dB, from -44.3 to -50.7 dBc, making the amplifier pass the 3GPP ACLR requirements.
ISSN:0018-9480
1557-9670
1557-9670
DOI:10.1109/TMTT.2012.2187532