Power Amplifier Test Solutions
Digital Predistortion, Envelope Tracking, Automated Characterization & Manufacturing Test
System Features
• Support for 802.11a/b/g/h/n/ac, UMTS,
LTE, and LTE-Advanced technologies
• Frequency range from 65 MHz to 6 GHz
• 200 MHz instantaneous bandwidth
• Integrated DC, Digitizer, and Digital I/O
DPD Reference Solution
• Measure AM-AM and AM-PM using
modulated waveforms
• Implement both lookup table (LUT)
and memory polynomial model
(MPM) DPD algorithms
Envelope Tracking Reference Solution
• Industry leading baseband-to-RF
synchronization
• Customizable Vcc waveform shaping
• Advanced digital synchronization with
DUT
Characterization & Manufacturing Test
Solutions
• FPGA-based power level servo
• 5x to 10x improvements in
measurement speed
PXI RF Power Amplifier Test Solutions
The demands of emerging wireless standards such as LTE Advanced and 802.11ac in conjunction with
RF power amplifier (PA) technologies such as envelope tracking (ET) and digital pre-distortion (DPD) are
creating new test challenges for today’s engineers. NI PXI offers complete solutions for PA testing from
initial product design to manufacturing test. Benefits of NI PXI solutions include:
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•
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Best-in-Class RF Measurement Performance
Industry-Leading Measurement Speed
Reduced Cost of Test
Modular Instruments
PXI modular instruments including RF signal
generators, RF signal analyzers, high speed
digital I/O, source measure units (SMUs),
switches, high-speed digitizers, and arbitrary
waveform generators (AWGs).
Embedded PC
Application Software
As an embedded PC, a PXI controller is the
heart of the PXI system and contains a highperformance multicore processor, deep
memory, and multiple hard drive options.
NI instrument soft front panel and reference
example software provides an easy-to-use
interface to modular instruments
DPD Reference Solution
ET Reference Solution
Test PAs using common DPD
models such as the memoryless
lookup table and the memory
polynomial model.
PXI solutions for envelope tracking
PA test feature best-in-class
synchronization between RF and
baseband signal generators.
Characterization and Manufacturing
Automated PXI test systems
reduce time to market and cost of
test through dramatic
improvements in measurement
speed.
www.ni.com/pa
Reference Solution Architecture
RF Signal Generator
& RF Signal Analyzer
GSM, UMTS, LTE, and WLAN
DPD and ET LabVIEW
Reference Examples
Reference Solution
Software
Soft Front Panel
Software
NI reference solutions for PA testing includes a combination software and PXI modular instruments. NI
software software includes LabVIEW reference examples or NI TestStand preconfigured test sequences
along with instrument soft front panels. All GUI’s automates PXI instruments through NI instrument
driver software such as NI-RFmx and other similar drivers.
Characterization & Manufacturing
TestStand Sequences
NI Instrument Driver Software
Hardware
PXI
System
Source
Measure Unit
PXI
Controller
High-Speed
Digitizer
High Speed
Digital I/O
NI Vector Signal
Transceiver
RF
Switching
Arbitrary Waveform
Generator
www.ni.com/pa
DPD Reference Solution Overview
Digital pre-distortion (DPD) is a popular technique to correct for signal distortion and improve PA metrics
such as ACLR and EVM. Testing a PA under DPD conditions involves four key operations: characterizing
device behavior, model extraction, model inversion, and application of predistortion to baseband IQ
samples.
A key element of the NI DPD reference solution is the easy-to-use LabVIEW DPD reference application.
This LabVIEW example code allows you to interactively apply DPD models and observe PA behavior. The
NI solution supports two common DPD models, the memoryless AM-AM/PM lookup table (LUT), and the
Memory Polynomial Model (MPM). You can also customize both the order and the number of taps when
implementing the MPM model – or even use your own custom model.
DPD Model Parameters
Performance Visualization
Choose between memoryless lookup
table and Memory Polynomial Model.
Observe improvements in spectral regrowth
and modulation quality in real time.
PA Linearity Measurements
PA Performance Metrics
Observe AM-AM and AM-PM response
of the PA with and without DPD.
Use metrics such as ACLR, EVM, power, and
RMS memory to characterize PA performance.
www.ni.com/pa
DPD Reference Solution Hardware Configuration
NI’s Digital Predistortion (DPD) Reference Solution combines multiple instruments into a single system
including the NI vector signal transceiver (VST), precision power supplies, and high speed digital I/O. The
NI VST is a key element of the measurement configuration and combines an RF signal generator and RF
signal analyzer into one module. Tight synchronization between RF signal generator and acquisition
enables you to accurately measure AM-AM/PM using modulated waveforms. NI PXI has the added
benefit of accelerating measurement speed of the highly mathematically complex memory polynomial
model using multicore processing technology.
PXI Chassis
PXI Controller
High Speed Digital
I/O & PPMU
Digital
I/O
Precision Source
Measure Unit
DCout
Vector Signal
Transceiver
MIPI RFFE Control
Stimulus
RFout
PA
RFin
Response
DPD Solution Features & Specifications
DPD Models
Included Products
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•
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•
•
Memoryless AM-AM/PM LUT
Memory Polynomial Model
Measurements
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AM-AM/PM
Power
EVM
ACLR
RMS Memory (Phase)
NI LabVIEW Software
NI PXIe-1085 18-Slot PXI Chassis
NI PXIe-8135 Embedded Controller
NI PXIe-5646R Vector Signal Transceiver
NI PXIe-4139 Source Measure Unit
NI PXIe-6556 High Speed Digital I/O
Supported Signal Types
•
•
•
UMTS (WCDMA, HSPA, HSPA+)
LTE / LTE-Advanced
WLAN 802.11a/b/g/h/n/ac
www.ni.com/pa
Envelope Tracking Reference Solution Overview
Envelope tracking (ET) is an increasingly popular technique to improve the efficiency of power amplifiers
for modern wireless signals with a high peak to average power ratios (PAPR). PA efficiency is highest
when a PA nears compression, an ET Power Supply (ETPS) is used to dynamically vary the power supply
in conjunction with the amplitude of a modulated wireless signal. Envelope tracking keeps a PA near
compression as often as possible – thus improving overall efficiency.
NI’s Envelope Tracking Reference Solution combines multiple instruments into a single system including
the NI vector signal transceiver (VST), arbitrary waveform generator (AWG), high-speed digitizers,
precision power supplies, and high speed digital I/O. The LabVIEW ET reference application provides an
easy-to-use interface to control each of these instruments – enabling you to characterize the performance
of ET PAs using UMTS and LTE signals.
DPD Algorithms
Apply DPD algorithms to ET PAs to
correct for AM-AM and AM-PM
distortion.
PA Performance
Observe AM-AM and AM-PM behavior of PA
under envelope tracking conditions.
Envelope Control
Applies envelope shaping and realtime control of VSG-to-AWG delay.
PA Performance Metrics
Use metrics such as ACLR, EVM, power, and
RMS memory to characterize PA performance.
www.ni.com/pa
Envelope Tracking Reference Solution Hardware Configuration
A critical challenge for ET PA Testing is synchronization and stable alignment of RF and Vcc signals
supplied by a vector signal generator (VSG) and arbitrary waveform generator (AWG). The NI Envelope
Tracking Reference Solution is based on NI PXI instrumentation and features shared trigger and timing
bus resources. This implementation produces synchronization jitter between RF and Vcc signals that is
less than 20 ps. In addition, by routing timing signals on the PXI backplane, these results are stable and
repeatable. The software includes the NI Fast ET Align measurement which rapidly estimates RF and Vcc
alignment.
Because modulating the power supply to a power amplifier can produce AM-AM and AM-PM distortion,
the NI ET reference solution software includes examples that apply DPD algorithms to the stimulus
signal.
PXI Chassis
PXI Controller
Precision Power
Supply
Arbitrary Waveform
Generator
High Speed Digital
I/O & PPMU
DCout
Shaped Envelope
Vcc
Out
Power
Modulator
MIPI RFFE Control
Digital
I/O
Ch0
High Speed Digitizer
Vector Signal
Transceiver
Splitter
Ch1
PA
RFout
Measure PA Behavior
RFin
Envelope Tracking Solution Features & Specifications
Synchronization
Included Products
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AWG-to-VSG Jitter: < 20 ps
AWG-to-VSG skew resolution: 1 ns
Supported Signal Types
•
•
•
UMTS (WCDMA, HSPA, HSPA+)
LTE / LTE-Advanced
WLAN 802.11a/b/g/h/n/ac
NI LabVIEW Software
NI PXIe-1085 18-Slot Chassis
NI PXIe-8135 Embedded Controller
NI PXIe-5646R Vector Signal Transceiver
NI PXIe-5451 Arbitrary Waveform Generator
NI PXIe-4139 Precision Source Measure Unit
NI PXIe-5162 High Speed Digitizer
NI PXIe-6556 High Speed Digital I/O
www.ni.com/pa
Power Amplifier Characterization Solution Overview
The emergence of new wireless technologies and multi-mode power amplifiers are increasing the
demands on automated power amplifier testing both in characterization and in high-volume
manufacturing test. NI PXI automated test systems deliver best-in-class RF measurement performance
with test times that are typically 5 to 10 times faster than traditional instruments.
The NI approach combines high-performance modular instruments with highly innovative measurement
software. Typical automated PA test systems include a combination of modular instruments and test
automation software and test PAs that use technologies such as: GSM/EDGE, UMTS
(WCDMA/HSPA/HSPA+), LTE/LTE-A, CDMA2000/EV-DO, and 802.11a/b/g/h/n/ac
“
With NI PXI, we were able to reduce the characterization
time of new parts from two weeks to about a day.
”
Gary Shipley, Senior Engineer
Triquint Semiconductor
NI Instrument Soft Front Panels
Using the signal generator and signal analyzer
soft front panels, you can use the RF vector
signal transceiver for interactive signal
generation and measurement.
The RF signal analyzer soft front panel supports
a wide range of measurements including
channel power, adjacent channel power (ACP),
complementary cumulative distribution function
(CCDF), intermodulation distortion (IMD), third
order intercept (TOI), and more.
NI TestStand Test Executive Software
NI TestStand is a ready-to-run test management
software that is designed to help you develop
automated test and validation systems faster.
TestStand sequences also specify execution
flow, reporting, database logging, and
connectivity to other enterprise systems.
When testing RF power amplifiers, you can
customize preconfigured sequences to fit your
applications needs.
www.ni.com/pa
Power Amplifier Automated Production Test
NI PXI test solutions combine RF measurements with precision DC instrumentation and high-speed
digital IO to provide a complete solution for high volume production test. By adopting NI PXI solutions,
our customers can dramatically lower their cost of test through faster measurements, lower capital
equipment cost, and fewer testers.
NI RF power amplifier test systems deliver the RF measurement performance required for R&D test
benches and the measurement speed and repeatability required for manufacturing test. Thus, you can reuse the same equipment and test software from initial product design through final production test. This
approach not only reduces test development time, but it also improves measurement correlation.
Device
Characterization
R&D Test Bench
Quickly validate PA behavior
using instrument soft front
panels or LabVIEW reference
examples.
Manufacturing Test
Characterize device behavior
of a wide range of operating
conditions by sweeping
frequency, Vcc levels, and
other settings..
Re-use test equipment and
characterization software
such as LabVIEW code and
TestStand sequences in
manufacturing test.
Fast Power Level Servo Technology
A unique technology of the NI power amplifier test solution is FPGA based power level servo using the NI
Vector Signal Transceiver (VST). Power level servo is traditionally a time consuming process. By
performing the control loop entirely on the instrument FPGA you can achieve the fastest possible power
level convergence. By decoupling the power level servo algorithm from the embedded controller and
performing it on an FPGA, test software is able to exploit dramatic measurement parallelism. This results
in significant reductions in test time and test cost.
PXI Chassis
PXI Controller
CPU
Memory
Data Transfer
FPGA
Vector Signal Transceiver
Digital
I/O
PA
RFout
RFin
www.ni.com/pa
Hardware Description
NI DPD and Envelope Tracking (ET) Reference Solutions are based on a standard configuration of PXI
modular instruments. One can use these instruments within with the LabVIEW Reference example code
or as standalone instruments.
PXIe-5646R Specifications (Signal Analyzer)
Frequency Range
65 MHz – 6 GHz
Bandwidth
200 MHz
Amplitude Accuracy
+/- 0.34 dB
Average Noise Floor
-161 dBm/Hz
802.11ac EVM
-45 dB
LTE EVM
-50 dB
PXIe-5646R Specifications (Signal Generator)
Frequency Range
65 MHz – 6 GHz
Bandwidth
200 MHz
Maximum Output Power
+15 dBm
802.11ac EVM
-45 dB
LTE EVM
-50 dB
UMTS ACLR
65 dB
NI PXIe-5646R Vector Signal Transceiver
The NI PXIE-5646R VST combines an RF vector
signal generator (VSG) and RF vector signal
analyzer (VSA) into one module. The
combination of wide bandwidth and high-quality
RF measurement performance make the NI
PXIe-5646R an ideal solution for RF power
amplifier testing.
Refer to PXIe-5646R Specifications Document for more details
PXIe-5451 Arbitrary Waveform Generator
Specifications
PXIe-4139 Precision Source Measure Unit
Specifications
Max Sample Rate
400 MS/s
Max Pulse Power
500 W
Bandwidth
145 MHz
Max Continuous Power
20 W
SFDR (1 MHz)
98 dB
Transient Response
< 70 μs
www.ni.com/pa
Hardware Description
NI DPD and Envelope Tracking (ET) Reference Solutions are based on a standard configuration of PXI
modular instruments. One can use these instruments within with the LabVIEW Reference example code
or as standalone instruments.
PXIe-5162 10-Bit Digitizer Specifications
PXIe-6556 High Speed DIO Specifications
Max Sample Rate
5 GS/s
Clock Rates
800 Hz – 200 MHz
Bandwidth (3 dB)
1.5 GHz
PPMU Channels
24
Max Channels
4
Voltage Ranges
-2 V to 7 V
PXIe-1085 Chassis Specifications
PXIe-8135 Embedded Controller Specifications
PXI Express Slots
18
Processor
2.3 GHz Quad Core
Total System Bandwidth
12 GB/s
Maximum Memory
16 GB DDR3
Total Power Rating
925 W
Operating System
Windows OS
www.ni.com/pa
For more information:
{
Heath Noxon
[email protected]
www.ni.com/pa
BDM, Semiconductor
(512) 683-5847
}
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