Hi, I'm Alejandro, an engineer with National Instruments.
Today, I want to show you how we are testing a power
amplifier for LTE applications using digital pre-distortion.
In my hardware setup, I have a vector signal transceiver,
which is an instrument that combines a 1 gigahertz
vector signal analyzer and generator in one instrument.
I also have a source measurement unit
to power my device and the power amplifier that I am testing.
Let's take a look now at the RFIC reference application
for power amplifier test based on LabVIEW.
The first thing I'm going to set up
is the dot configuration, where I set up
the expected gain, target power, and frequency of operation.
Then I can go to the Measurements
and select the algorithm that I want to use.
In this case, I've selected a lookup table algorithm
to process this five-carrier aggregated LTE signal.
Let me turn on the digital pre-distortion,
and the vector signal transceiver
is now pre-distorting the signal and applying that input
to the power amplifier.
We see here the nonlinear effects
of the amplifier, causing spectral regrowth
and modulation quality degradation.
The memory effects are especially evident when
we look at the gain versus power plot and phase
versus power plots.
Now let's use a memory polynomial.
This is a fifth-order polynomial.
The VST is taking then 500 megahertz
of real-time bandwidth to pre-distort the signal
and apply that stimulus to the power amplifier.
Notice that we still get that adjacent channel power
correction, and we are taking care of some of those memory
effects using this algorithm.
Also, if we look at the ACP Results table here,
we see a correction of about 8 db.
In addition, you can use the Power [INAUDIBLE] view
and the flexibility of the vector signal transceiver
to implement your own digital pre-distortion algorithms.
That's how you can characterize and test
the performance of your wideband power amplifiers
using the vector signal transceiver and LabVIEW.
To learn more, visit ni.com/vst.