IEEE－A Linearization Technique for CMOS RF Power Amplifiers（by Abidi）

semico_ljj

A Linearization Technique for CMOS RF Power Amplifiers

S. Tanaka, F. Behbahani, and A. A. Abidi
Electrical Engineering Department
University of California

Introduction
The next generation of wireless transceivers for LAN applications
will support data rates many orders of magnitude higher than today’s
mainly voiceband wireless devices. They will accomplish this with
spectrally efficient modulation schemes, such as multi-level QAM,
and also pack more channels into the available operating frequency
band in every microcell. This requires a highly linear, yet efficient
power amplifier in the transmitter.
This paper describes a compact, yet general, linearization method
well-suited to CMOS power amplifiers. It is intended for use in a
high bit-rate wireless system signalling with 64-QAM, and using
every channel in each cell. The latter demands higher power amplifier
linearity, as is now explained. 3rd-order intermodulation distortion
between the tones comprising a modulated spectrum causes
energy to spill over into the immediately adjacent channels (Fig.1),
while the much smaller 5th-order distortion spills energy into the
alternate channels. For this reason, wireless systems today use every
other channel in a given cell, guaranteeing that a transmitter in
the alternate channel spills only a small energy into a given channel,
and does not significantly interfere with the user assigned this channel.
Our system consumes more spectrum per channel to carry data
at rates > 10Mb/s, but makes up some of the lost capacity with a
more linear power amplifier which allows use of every channel in a
cell. The specification is to leak less than –50 dBc into the adjacent
and other channels at an RF output power of 20 mW (2.8V ptp into
50V). A power-added efficiency of 5 to 10% is acceptable in such a
high performance transceiver.
System-level methods, such as predistortion [1], feedforward
error-cancellation [2], and Cartesian feedback [3], have been proposed
to linearize efficient, and therefore nonlinear, power amplifiers.
However, they all require complex hardware, and may be better
suited to base stations. A transistor-level linearization is more appropriate
for the power amplifier in the handset.

cupt000

楼主，能否介绍一下内容呢？

xileito

thank you for your sharing

xileito

还行  谢谢了

muyangtong

rylx

谢谢，正在找这篇paper

yyneuq2008

谢谢楼主分享

2010.01.27

need!in deed!

weissue

xiexie

lawrence312

谢谢楼主分享下下来看看