Wireless Design & Development   RF Envelope Detection Enables
Drain Modulation Systems Mon, 02/14/2011 - 10:14am By Eamon Nash
and Ashraf Elghamrawi, RF Group, Analog Devices, Inc.  Improving
the Power Added Efficiency (PAE) of High Powered Amplifiers
continues to be a challenging goal in a Wireless equipment
industry that is struggling to deliver cheaper, smaller
equipment that consumes either less electricity or in the case
of portable devices, less battery current. An array of
techniques is currently being researched. In most cases the
commercialization of any technique will depend on the
development of breakthrough technology. This article will focus
on some of the techniques being used to improve PAE and some of
the RF signal processing blocks that are enabling this
technology.  Peak-to-Average Ratio Challenges of LTE Basestation
and Handset Testing click to enlarge  Figure 1. Time envelope of
an Orthogonal Frequency Division Multiplexed (OFDM) carrier with
a Bandwidth of 20 MHz. Figure 1 shows the time