NI NIPXI-2546 Dual-channel, differential i/q signal generation Datasheet

400 MS/s, 16-Bit I/Q Signal Generator
NI PXIe-5450 NEW!
• Dual-channel, differential I/Q
signal generation
• 16-bit resolution, 400 MS/s
sampling rate per channel
• 98 dB close-in SFDR at 1 MHz
• 145 MHz analog bandwidth for
generating 290 MHz bandwidth RF signals
• ±0.15 dB flatness to 120 MHz with
digital flatness correction
• 25 ps channel-to-channel skew
• <-140 dBc/Hz phase noise density for
10 MHz tone (1 kHz offset)
• -160 dBm/Hz average noise density
• 128 or 512 MB of deep
onboard memory
• Continuous data streaming
>600 MB/s from host
• 1 Vpk-pk output, 2 PXI slots
Operating Systems
• Windows Vista/XP/2000
Recommended Software
•
•
•
•
LabVIEW
LabWindows™/CVI
LabVIEW SignalExpress
Measurement Studio
Included Software
•
•
•
•
•
•
NI-FGEN driver
NI-FGEN Express VIs
NI Modulation Toolkit
NI Analog Waveform Editor
FGEN Soft Front Panel
LabVIEW Real-Time driver
Calibration
• Self-calibration with gain and channel
alignment; offset correction
• 1-year external calibration cycle
Overview
Signal Quality
The NI PXIe-5450 is a 16-bit, 400 MS/s, dual-channel arbitrary waveform
generator optimized for I/Q communications signals. Each of the differential
outputs features 98 dB of close-in spurious-free dynamic range (SFDR) at
1 MHz (without harmonics), better than -140 dBc/Hz phase noise density
at 10 MHz (1 kHz offset), and less than 25 ps channel-to-channel skew.
The NI PXIe-5450 is the ideal instrument to test devices with I/Q inputs
or to serve as the baseband component of an RF vector signal generator.
It also features onboard signal processing (OSP) functions that include
pulse shaping and interpolation filters, gain and offset control, and a
numerically controlled oscillator (NCO) for frequency shifting. Common
applications include prototyping, validating, and testing of semiconductor
components and communications, radar, and electronic warfare systems.
With its NI Synchronization and Memory Core (SMC) architecture, the
NI PXIe-5450 helps you integrate mixed-signal test systems by enabling
synchronization with other instruments such as vector signal analyzers/
generators, high-speed digitizers, digital waveform analyzers/generators,
and other signal generators. You can also synchronize multiple arbitrary
waveform generators to form a phase-coherent multichannel generator
for applications such as MIMO (multiple-input, multiple-output) or
beamforming antenna schemes.
With 16 bits of resolution, the NI PXIe-5450 achieves a close-in SFDR
(without harmonics) of 98 dB at 1 MHz. Including harmonics and
measured from DC to 200 MHz, it achieves a 1 MHz SFDR of 75 dB and
a wideband SFDR of 70 dB at 60 MHz. This ensures the dynamic range
and out-of-band performance needed to meet the stringent demands of
baseband I/Q signal generation (Figure 1).
Figure 1. With its high sample rate and resolution, the NI PXIe-5450 generates
low-distortion, high-SFDR signals over a very high bandwidth (the noise floor is
limited by the measurement device).
400 MS/s, 16-Bit I/Q Signal Generator
The NI PXIe-5450 also delivers exceptional passband flatness (Figure 2).
While the -3 dB analog bandwidth is 145 MHz, the digital flatness
correction filter provides ±0.15 dB of flatness from DC to 120 MHz.
1–
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Amplitude (dB)
–1.5 –
–2 –
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Flatness Correction Enabled
Flatness Correction Disabled
–5 –
20
40
60
80
100
120
140
160
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180
Figure 3. Dedicated channel-alignment circuitry automatically calibrates the two channels
on the NI PXIe-5450 to within 25 ps. This particular module exhibits less than 13 ps of
skew, demonstrated on a 100 MHz sinusoid.
Frequency (MHz)
Figure 2. Passband flatness is significantly improved with the use of digital flatness
correction in the NI PXIe-5450 FPGA.
For maximum signal purity, the phase noise of this module is
extremely low. The phase noise density of a tone generated at 10 MHz
drops from -121 dBc/Hz at a 100 Hz offset to -150 dBc/Hz at 100 kHz,
yielding an integrated system output jitter of less than 500 fs. Its highly
stable phase-locked loop (PLL) and high-resolution oscillator provide an
output sample rate resolution less than 5.7 µHz, enabling low phase
noise signal generation at any frequency with microhertz resolution.
An essential attribute for I/Q generation is tight synchronization
between channels. The NI PXIe-5450 features high-performance circuitry
that calibrates the channel skew to within 25 ps. You can achieve even
more alignment with a 10 ps resolution programmable skew, useful in
calibrating out cable length mismatches. This tight level of
synchronization minimizes the phase error between channels, especially
at high frequencies, which is essential for accurately generating highbandwidth I/Q signals (Figure 3).
High-Speed Data Streaming
In addition to tight synchronization, the SMC architecture on the
NI PXIe-5450 takes advantage of the PCI Express bus to continuously
stream data from the host controller at more than 600 MB/s in dual-channel
mode or at 360 MB/s when generating a single channel. This enables the
module to continuously output I/Q waveforms at 150 MS/s or, when
upconverted, approximately 120 MHz RF bandwidth, either from host
memory or a high-speed storage solution such as the NI HDD-8264 3 TB
RAID array. With this technology, you can generate terabyte waveforms
of unique, high-bandwidth data for several hours. Applications that
benefit from this capability include RF and baseband recording and
playback for signal intelligence and communications system design,
validation, and verification.
Onboard Signal Processing
OSP significantly extends waveform playback time and shortens
waveform download times (Figure 4). A field-programmable gate array
(FPGA) on the NI PXIe-5450 implements the OSP functionality, which
enables several signal processing and I/Q-related functions. These
functions include those listed on page 3.
Onboard Signal Processing
Waveform
Memory
Output
Engine
I/Q
Rate
Pre-Filter
Gain I
Pre-Filter
Offset I
Filtering
and Interpolation I
Pre-Filter
Gain Q
Pre-Filter
Offset Q
Filtering
and Interpolation Q
Frequency
Shift
by NCO
Digital
Gain I
DAC I
Digital
Gain Q
DAC Q
Figure 4. OSP on the NI PXIe-5450 FPGA performs inline processing of waveform data
before it is sent to the digital-to-analog converter (DAC) .
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2
400 MS/s, 16-Bit I/Q Signal Generator
• Independent I and Q prefilter gain and offset – Adds gain and
offset imbalance impairments and I and Q prefilter gain. You can adjust
the offset before or during the generation of an output signal (Figures 5, 6).
• Baseband interpolation – Generates smooth baseband signals.
You can use the NI PXIe-5450 OSP block to interpolate low-sample
rate waveforms to a much higher sample rate, thereby improving the
output frequency spectrum by relocating zero-order sample-and-hold
reconstruction images to higher frequencies. With the images at
higher frequencies, the device’s image suppression filter greatly
suppresses them without disturbing the signal’s amplitude response
or phase information.
Waveform Sequencing and Triggering
Figure 5. LO leakage and poor image rejection of a quadrature modulator cause
undesired RF emissions.
You also can program the NI PXIe-5450 to sequence and loop a set of
waveforms. You can choose from several methods to step through the
sequence of waveforms. In cases when you know the duration of each
waveform in advance, you can program the generator to loop them a
specified number of times. When you do not know the duration before
the start of generation, you can use a hardware or software trigger to
advance the generator to the next waveform in the sequence. The
NI PXIe-5450 implements advanced triggering behavior with four trigger
modes: single, continuous, burst, and stepped. In addition, scripting
provides the ability to link and loop multiple waveforms together, managing
triggers and markers. For a detailed discussion of these modes, consult
the NI Signal Generators Help guide available at ni.com/manuals.
NI SMC-based generators have the unique capability of storing
multiple sequences and their associated waveforms in the generator’s
onboard memory (see Figure 7). In automated test applications involving
multiple tests, each requiring a different waveform sequence, you can
download all of the sequences and waveforms once at the beginning
of the test cycle and store them in the generator’s memory for the entire
session. By downloading all required waveforms and sequences once to
an SMC-based generator instead of repeatedly reloading them for each
test, you save time and improve throughput.
Waveform
1
Waveform
2
•••
Waveform
n
Sequence
Instructions
1
Sequence
Instructions
2
•••
Sequence
Instructions
m
Free
Memory
Figure 7. NI SMC-based arbitrary waveform generators increase test throughput by
storing all the waveforms and sequences required for a set of tests in onboard memory.
Figure 6. On-the-fly-adjustable parameters on the NI PXIe-5450 correct for the
quadrature modulator impairments seen in Figure 5.
• Pulse-shaping finite impulse response (FIR) filter – Shapes and
interpolates the waveform data. FIR filter types include flat, raised
cosine, and root raised cosine, with a programmable α parameter.
Digital interpolation factors range from 2 to 32,768 times.
• Numerically controlled oscillator (NCO) – Produces sinusoidal
waveform data for complex (I/Q) frequency shifts before or during
generation with up to a ±86 MHz shift and 710 nHz resolution.
NCO tuning time is 250 µs.
Timing and Synchronization
Using NI T-Clock (TClk) synchronization technology, you can synchronize
multiple NI PXIe-5450 modules for applications requiring a greater
number of channels, such as I/Q signal generation for MIMO systems.
Because it is built into the SMC, TClk can synchronize the NI PXIe-5450
with SMC-based vector signal analyzers and generators, high-speed
digitizers, and digital waveform generators and analyzers for tight
correlation of analog and digital stimulus and response. Using onboard
calibration measurements and compensation, TClk can automatically
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3
400 MS/s, 16-Bit I/Q Signal Generator
synchronize any combination of SMC-based modules with less than 500 ps
module-to-module skew. Greatly improved from traditional synchronization
methods, the skew between modules does not increase as the number of
modules increases. To achieve even better performance, you can use a
high-bandwidth oscilloscope to precisely measure the module-to-module
skew. With the oscilloscope measurement for calibration information,
TClk can achieve <20 ps module-to-module skew.
NI PXIe-5450 clocking is very flexible. Its internal, DDS-based clock
is optimized for phase noise performance, and has better than 5.7 µHz
frequency resolution. The module can also import its sample clock from
the CLK IN front panel connector and multiply and divide this clock’s
frequency by integers. Finally, the NI PXIe-5450 can phase-lock its internal
clock to an external reference or the PXI 10 MHz reference clock.
Driver Software
Accurate, high-throughput hardware improves the performance of a
measurement system, but easy-to-use, reliable software reduces
development time and ongoing support costs. NI-FGEN, the driver
software for the NI PXIe-5450, is the world’s most advanced and
thoroughly tested arbitrary waveform generator software. It features:
• Intuitive application programming interface (API) – In NI LabVIEW
and LabWindows/CVI as well as Microsoft Visual Basic and Visual
C/C++, the NI-FGEN API is engineered to use the least number of
functions possible while maintaining flexibility. Each driver function has
thorough online searchable documentation. The NI-FGEN Instrument Driver
Quick Reference guide further simplifies programming by providing an
overview of each driver function’s LabVIEW icon, function name, parameters,
and data types.
• LabVIEW Express VIs – For generating an arbitrary repetitive signal,
the LabVIEW Express VI is a configuration-driven method of programming
the NI PXIe-5450 without accessing the underlying NI-FGEN functions.
• Soft Front Panel – For quick, nonprogrammatic use of the NI PXIe-5450,
the Soft Front Panel supports arbitrary waveform generation.
• Example Programs – NI-FGEN provides 23 programming examples for
LabVIEW, LabWindows/CVI, Visual C++ 6.0 and .NET, and Visual Basic 6.0,
giving developers references on which to base custom applications.
• LabVIEW Real-Time Support – For remotely deployed, autonomous
measurement systems or applications requiring the highest possible
reliability, NI-FGEN works with the LabVIEW Real-Time Module.
Modulation Toolkit for LabVIEW 1
The NI Modulation Toolkit for LabVIEW provides functions for signal
generation, analysis, and visualization of custom and standard analog
and digital modulation. With the Modulation Toolkit, you can develop
and analyze custom modulation formats and generate these with the
NI PXIe-5450. Some of the standard measurement functions include
error vector magnitude (EVM), modulation error ratio (MER), and ρ (rho).
Functions are also available for injecting impairments including IQ gain
imbalance, quadrature skew, and additive white Gaussian noise (AWGN).
Visualization functions include trellis, constellation, and 2D and 3D eye
diagrams. This hardware and software combination gives you access to
customizable functionality not available in traditional instrumentation.
Modulation/Demodulation
•
•
•
•
•
•
4-, 8-, 16-, 32-, 64-, 128-, 256-QAM
2-, 4-, 8-, 16-FSK
MSK and GMSK
8-, 16-, 64-PSK
BPSK, QPSK, OQPSK, DQPSK, π/4DQPSK
AM, FM, PM
Modulation Analysis Functions
•
•
•
•
•
•
ρ (rho)
Phase error
IQ gain imbalance
Frequency deviation
Burst timing measurements
Error vector magnitude
•
•
•
•
•
DC offset
Quadrature skew
Bit error rate (BER)
Additive white Gaussian noise
Modulation error ratio (MER)
Visualization and Analysis
• Trellis diagrams
• Constellation plot
• 2D and 3D eye diagrams
Modulation Impairments
• Multitone
• Fading profile
• Quadrature skew
1The
• DC offset
• Frequency offset
• IQ gain imbalance
NI Modulation Toolkit data sheet is available separately.
Analog Waveform Editor2
The NI Analog Waveform Editor is an interactive software tool for
creating and editing analog waveforms. In the editor, each waveform
comprises different components, and each component comprises a
collection of primitives. You can create a new waveform segment by
selecting from a library of more than 20 waveform primitives (Table 1),
by entering a mathematical expression, or by importing data from a file.
You can then combine waveform primitives point-by-point using addition,
subtraction, multiplication, or division to create more complex segments
(Figure 8). You can also concatenate multiple segments to make a larger
waveform. To further process the waveform, you can apply standard or
custom FIR and IIR filters or smooth any discontinuities between different
waveform segments. Once complete, all the waveform settings are
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400 MS/s, 16-Bit I/Q Signal Generator
stored along with the waveform’s raw sample data, making it easy to
reload the waveform in the editor and modify the settings of a particular
segment or primitive.
2The
NI Analog Waveform Editor data sheet is available separately.
Figure 8. You can combine more than 20 different waveform primitives to create more
complex waveforms.
Waveform Primitives
Sine
Square
Triangle
Sawtooth
Uniform noise
Triangular noise
Gaussian noise
Sinc
Gaussian pulse
Exponential rise/decay
Trapezoid
Stairstep
Haversine
Impulse
Lorentzian pulse
Table 1. Partial List of Configurable Waveform Primitives Available in the NI Analog
Waveform Editor
Specifications
For complete specifications, see the NI PXIe-5450 Specifications manual
at ni.com/manuals.
Ordering Information
NI PXIe-5450 ......................................................................780419-0M1
1M (onboard memory): 1 (128 MB), 2 (512 MB)
Includes NI-FGEN driver, FGEN Soft Front Panel, NI Modulation Toolkit for LabVIEW, and
NI Analog Waveform Editor.
Recommended PXI Switch
NI PXI-2546............................................................................778572-46
Note: All images show typical results for one production-quality
NI PXIe-5450.
BUY NOW!
For complete product specifications, pricing, and accessory
information, call 800 813 3693 (U.S.) or go to ni.com/signalgenerator.
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*351631A-01*
351631A-01
2008-9814-101-D
©2008 National Instruments. All rights reserved. CVI, LabVIEW, Measurement Studio, National Instruments, National Instruments Alliance Partner, NI, ni.com, SCXI, and SignalExpress
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