Signal Generator Settings
R&S
®
SGT100A
146
User Manual 1176.8674.02 ─ 07
7.5 Generation of Envelope Tracking Signals
The envelope tracking (ET) is a method used by modern power amplifiers (PA) to
improve their efficiency, especially when they amplify RF signals with a high peak to
average power (PAPR). An envelope tracking detector "tracks" the power variations in
the input signal of the PA; the PA then varies synchronously to this variation the supply
voltage v
cc
at its end amplifying stage.
This section introduces the concept of the envelope tracking functionality and the way
it is implemented in the R&S
SGT.
7.5.1 Required Options
The equipment layout for generation and output of envelope tracking signal includes:
●
Option Differential Analog I/Q Outputs (R&S
SGT-K16)
●
Option Envelope Tracking (R&S
SGT-K540)
●
Optional option AM/AM AM/PM Predistortion (R&S
SGT-K541)
7.5.2 About the Envelope Tracking
Provided the required options are installed, the R&S
SGT allows you to generate an
envelope tracking signal, that follows the envelope variation of the RF signal.
Principle of the envelope tracking
shows a simplified test setup for testing of a PA with an envelope track-
ing. This illustration is intended to explain the principle in general, not all connections
and required equipment are considered.
Figure 7-9: Simplified test setup for power amplifier envelope tracking tests
The R&S
SGT in this setup is configured to generate both, an RF signal with complex
modulation scheme and an envelope signal, that follows the envelope variation of this
RF signal. A suitable test signal is for example an EUTRA/LTE DL signal.
Generation of Envelope Tracking Signals
