190952E-02L

National Instruments PCI-5421 / PXI-5421 100 MS/s, 16-Bit Arbitrary Waveform Generators
Features

• 12 Vp-p Into 50 Ω Load
• Up to 400 MS/s Effective Sampling Rate with Interpolation
• 91 dBc Close-in SFDR and -62 dBc THD at 10 MHz
• 8, 32, 256, or 512 MB of Onboard Memory
• -148 dBm/Hz Average Noise Density
• Optional 16-bit LVDS Digital Pattern Output

The NI 5421 Series are 100 MS/s arbitrary waveform generators (AWG) featuring 16-bit resolution and up to 256 MB of onboard memory in a compact, 1 slot 3U PXI module or PCI board. With this combination of high resolution and deep memory, the user can generate long, precise aperiodic waveforms, ideal for a range of applications in communications, consumer electronics, scientific research, automotive, and military/aerospace. Because the NI 5421 Series use the PCI bus, waveforms can be downloaded up to 280 times faster than with GPIB-based AWGs. With the NI Synchronization and Memory Core (SMC) architecture of the NI 5421 Series, the user can create stimulus/response systems with digitizers and digital waveform generator/analyzers or synchronize multiple arbitrary waveform generators to form a phase-coherent multichannel system.

Analog Output Performance

Because of its 100 MS/s, 16-bit digital-to-analog converter (DAC) and clean back-end analog design, the NI 5421 Series have close-in spurious-free dynamic range (SFDR) of 91 dBc and an average noise density of -148 dBm/Hz. These features make it ideal for even the most stringent frequency-domain applications common in communications. Depending on the signal and application needs, the user can select from 2x, 4x, or 8x interpolation for an effective sampling rate up to 400 MS/s. For demanding time-domain applications, the NI 5421 Series have rms jitter at the analog output.

The analog output path features a 43 MHz 7-pole elliptical analog filter to suppress undesired high-frequency signal images. The user can also choose from 50 or 75 ? output impedance and vary the output attenuation with three digits of accuracy. In addition, one can bypass the output gain and attenuation by using the direct path. The direct path excels at intermediate frequency (IF) applications with passband flatness of ±0.25 dB from 0 to 40 MHz.

Shared Waveform and Instruction Memory

Because the NI 5421 Series aer built on the SMC architecture, they use the same physical memory for both waveform data and sequencing instructions. Traditionally, the instruction memory of AWGs is physically separate from the waveform data memory and is typically only a few kB. The limited instruction memory of traditional AWGs severely limits the maximum number of waveforms that can be sequenced as well as the overall flexibility of the AWG. The NI 5421 Series' onboard memory of 8, 32, or 256 MB stores data and instructions together, giving the flexibility to use as much space as needed for sequencing instructions. With shared memory, one can use the memory space for very long sequences with small waveforms, short sequences with very large waveforms, or a balance in between.

Triggering and Sequencing

The NI 5421 Series have four triggering modes for controlling the starting and stopping of waveform generation – single, continuous, stepped, and burst. With these triggering modes combined with the linking and looping flexibility of the NI 5421 Series, one can create sophisticated waveforms. With the 256 MB memory configuration, more than 1 million waveforms can be stored in memory and linked in any order. Each waveform segment can be looped up to 16,777,216 times or looped indefinitely. Triggers can be received from software as well as the front panel connectors, PXI trigger lines, PXI star trigger, or RTSI bus.

LVDS Digital Pattern Output

In addition to generating analog signals, the 32 and 256 MB configurations of the NI 5421 Series can generate low-voltage differential signal (LVDS) digital patterns. The LVDS is increasingly used for digital signaling because of its reduced power consumption, lower electromagnetic interference, and immunity to noise. The digital patterns generated on the digital data and control (DDC) front panel connector correspond to the analog waveform being generated and make use of all of the linking, looping, triggering, and timing features. The sample clock is also available on the DDC I/O connector to latch the digital patterns. Alternatively, the user can externally clock the NI 5421 Series via the DDC front panel connector. The NI Digital Waveform Editor is available as an add-on software package to provide further functionality in creating LVDS digital patterns.

Timing and Synchronization

The NI 5421 Series sample clocks have three modes – Divide-by-N, HighResolution, and External. Using the Divide-by-N sample clock, the jitter of the analog output is

With synchronization, the user can create mixed-signal test systems by combining the NI 5421 with other modular instruments such as the NI 5122 digitizer and/or the NI 655x digital waveform generator/analyzer. One can also synchronize two or more NI 5421 modules to build a multichannel phase coherent AWG, important for applications such as I and Q signal generation or antilock brake system simulation.

To trigger other instruments such as oscilloscopes, the NI 5421 can generate marker event outputs. A marker event can be placed in a different location in each waveform segment.