WEBVTT
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Hi, I'm Alejandro, an engineer
with National Instruments.

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Today, I want to show you
how we are testing a power

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amplifier for LTE applications
using digital pre-distortion.

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In my hardware setup, I have
a vector signal transceiver,

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which is an instrument
that combines a 1 gigahertz

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vector signal analyzer and
generator in one instrument.

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I also have a source
measurement unit

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to power my device and the power
amplifier that I am testing.

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Let's take a look now at the
RFIC reference application

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for power amplifier
test based on LabVIEW.

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The first thing
I'm going to set up

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is the dot configuration,
where I set up

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the expected gain, target power,
and frequency of operation.

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Then I can go to
the Measurements

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and select the algorithm
that I want to use.

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In this case, I've selected
a lookup table algorithm

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to process this five-carrier
aggregated LTE signal.

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Let me turn on the
digital pre-distortion,

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and the vector
signal transceiver

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is now pre-distorting the
signal and applying that input

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to the power amplifier.

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We see here the
nonlinear effects

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of the amplifier,
causing spectral regrowth

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and modulation
quality degradation.

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The memory effects are
especially evident when

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we look at the gain versus
power plot and phase

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versus power plots.

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Now let's use a
memory polynomial.

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This is a fifth-order
polynomial.

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The VST is taking
then 500 megahertz

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of real-time bandwidth
to pre-distort the signal

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and apply that stimulus
to the power amplifier.

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Notice that we still get
that adjacent channel power

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correction, and we are taking
care of some of those memory

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effects using this algorithm.

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Also, if we look at the
ACP Results table here,

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we see a correction
of about 8 db.

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In addition, you can use
the Power [INAUDIBLE] view

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and the flexibility of the
vector signal transceiver

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to implement your own digital
pre-distortion algorithms.

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That's how you can
characterize and test

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the performance of your
wideband power amplifiers

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using the vector signal
transceiver and LabVIEW.

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To learn more, visit ni.com/vst.

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