Генераторы сигналов PXI

NI PXI Signal Generators and Arbitrary Waveform Generators

What Is a PXI Signal Generator?

A PXI signal generator converts digitally defined waveform data into a controlled analog output. The generated signal stimulates a device under test, while another instrument measures the DUT response.

A typical automated stimulus-response path is:

PXI Signal Generator → Device Under Test → PXI Measurement Instrument

Test software can change waveform shape, frequency, amplitude, offset, phase and sequence without manual instrument adjustment. Hardware triggers and PXI timing resources allow the generated stimulus to be coordinated with acquisition, switching and other test operations.

Main Types of PXI Signal Generators

Representative NI PXI Signal Generator Models

The model number alone does not indicate whether a generator is the best choice. Compare bandwidth, arbitrary-waveform rate, output range, memory, streaming, channel count, synchronization and software compatibility for the actual test requirement.

How to Select a PXI Signal Generator

1. Define the Required Waveform Type

Determine whether the DUT needs standard repetitive functions or a user-defined waveform. A clock or function generator may be sufficient for sine, square and clock stimulus. An AWG is required when the application must reproduce a custom transient, recorded signal, sensor profile, distortion pattern or fault condition.

Also identify whether several waveforms must be played in a controlled sequence. Waveform scripting can select, repeat and branch between stored records without transferring every sample again from the controller.

2. Select the Required Analog Bandwidth

Analog bandwidth describes the frequency range over which the output path maintains its specified response. Select enough bandwidth for the highest waveform component that must reach the DUT accurately.

A square wave or fast pulse contains harmonics above its repetition frequency. A generator that produces the correct fundamental frequency may still round the edges if its analog bandwidth is insufficient.

3. Distinguish Bandwidth from Update Rate

Update rate describes how quickly the DAC produces waveform samples. Analog bandwidth describes the usable frequency response of the output path. These specifications are related but cannot be treated as equivalent.

Oversampling and fractional resampling can improve waveform placement and reconstruction, but a high internal DAC rate does not guarantee that every generated frequency passes through the analog output without attenuation or distortion.

4. Choose DAC Resolution for the Signal Requirement

DAC resolution defines the number of digital amplitude levels available to represent the waveform. Higher resolution can improve small-signal representation and amplitude granularity, but it does not independently determine output accuracy or signal purity.

Evaluate resolution together with noise, distortion, gain accuracy, offset accuracy, output range and the sensitivity of the DUT.

5. Calculate the Required Output Voltage

Record the minimum and maximum required amplitude, DC offset and transient peaks. Confirm whether the published range applies to a high-impedance load or a terminated 50 Ω load.

The PXIe-5413, PXIe-5423 and PXIe-5433 can provide up to ±12 V into high impedance. The achievable voltage into 50 Ω is lower because the source and load form a terminated signal path.

6. Verify Output Impedance and Load

Many waveform generators are designed for a 50 Ω signal environment. Connecting a high-impedance DUT without using the correct software or amplitude setting can produce a different voltage from the expected terminated value.

Confirm:

• Generator output impedance
• DUT input impedance
• Cable impedance
• Required termination
• Maximum output current
• Capacitive or reactive load behavior

A waveform generator is not a programmable power supply or power amplifier. External amplification may be required to drive speakers, actuators, transformers or other high-power loads.

7. Select One or Two Output Channels

Two-channel models can generate independent waveforms for differential stimulus, I/Q baseband signals, dual-sensor simulation and multi-input DUT testing. Verify whether both channels must operate at different rates or from independent generation engines.

For systems requiring more than two channels, determine whether several modules can be synchronized with the required phase and trigger accuracy.

8. Calculate Waveform Memory

Waveform memory limits how many samples can be stored locally. Approximate record duration can be calculated as:

Waveform duration = stored samples ÷ programmed waveform rate.

Memory requirements increase with sample width, channel count, waveform rate and the number of stored records. Account for sequence tables, alignment restrictions and reserved memory where applicable.

9. Determine Whether Streaming Is Required

Onboard generation is appropriate when the complete waveform or sequence fits in module memory. Streaming is useful when the record is larger than onboard memory or must change continuously while generation is running.

Sustained streaming depends on the complete path, including the controller, host memory, PXIe slot, chassis segment, driver buffer and application architecture. A module’s waveform bandwidth does not define its sustainable stream-from-host rate.

10. Review Scripting and Sequencing

Waveform scripting allows stored records to be repeated, linked and selected in a predefined order. It can reduce software latency because the module performs the sequence locally after the waveform data has been downloaded.

Check whether the application requires loops, triggers, conditional transitions, marker events or rapid switching between waveform segments.

11. Define Triggering and Synchronization

Signal generators may need to start from an external event, align with a digitizer or operate phase-coherently with other output modules. Determine which reference clocks, start triggers, marker events and PXI backplane routes are required.

Sharing a reference clock controls frequency drift but may not guarantee identical waveform phase. Repeatable phase alignment can also require synchronized start triggers and device-specific configuration.

12. Confirm Chassis Compatibility

The PXI-5404 and PXI-5441 use PXI hybrid-compatible connections, while the PXIe-5413, PXIe-5423 and PXIe-5433 require PXI Express-compatible slots.

Review the exact slot map of the selected Шасси PXI. Physical installation, bus compatibility, cooling and synchronization resources must all be confirmed.

Function Generator vs Arbitrary Waveform Generator

PXI Signal Generator vs Analog Output DAQ

If the application only requires static or slowly changing control voltages, a PXI data acquisition module may be sufficient. Use a dedicated AWG when waveform fidelity, bandwidth, sequencing, memory or synchronization is central to the test.

Output Signal Integrity

Waveform quality depends on more than bandwidth and resolution. Important specifications may include:

• Total harmonic distortion
• Spurious-free dynamic range
• Output noise
• Frequency accuracy
• Clock jitter
• Amplitude and offset accuracy
• Channel-to-channel skew
• Rise and fall time
• Settling time
• Flatness across the required bandwidth

The signal source should provide better performance than the DUT requirement when the test must distinguish DUT distortion, noise or nonlinear behavior from imperfections in the generated stimulus.

Reconstruction Filtering and Waveform Images

A DAC output contains the desired waveform and frequency images related to the update process. Reconstruction filters attenuate unwanted high-frequency content and smooth the generated analog waveform.

Filter selection can affect bandwidth, amplitude flatness, transient response and waveform delay. Verify whether the application prioritizes spectral purity, fast pulse edges or accurate time-domain reproduction.

Waveform Generation and PXI Switching

A suitable PXI switch can route one signal generator to several DUT points or multiple test fixtures. This can reduce the number of generator channels required in an automated production system.

The switch becomes part of the analog signal path and must support the waveform voltage, current, bandwidth, impedance and required signal fidelity. A relay module intended for DC routing may not preserve fast edges or higher-frequency waveforms.

Synchronizing Generation and Acquisition

Stimulus-response applications frequently require the signal generator and measurement instrument to share a reference clock and coordinated triggers. This allows the DUT response to be captured at a repeatable position relative to the generated waveform.

Pair the generator with PXI oscilloscopes and digitizers for waveform capture. Advanced multi-instrument or multichassis systems may require dedicated PXI timing hardware and calibrated delay correction.

Software and NI-FGEN

NI PXI waveform generators use NI-FGEN for configuration and programmatic control. Compatible applications can configure:

• Standard function and arbitrary-waveform modes
• Amplitude, offset, frequency and phase
• Waveform memory and data download
• Sequencing and scripting
• Start, script and marker triggers
• Reference clocks and synchronization
• Output enable and generation status

NI-FGEN can be used with LabVIEW, TestStand and supported text-based programming environments. InstrumentStudio can support interactive configuration of compatible PXI waveform generators.

Before purchasing hardware for an existing system, verify the operating system, NI-FGEN version, application bitness and development-environment compatibility.

Типичные применения

• Electronic circuit and component validation
• Semiconductor characterization and production test
• ADC and mixed-signal converter testing
• Sensor and transducer simulation
• ECU and industrial-controller input simulation
• Audio and baseband testing
• Amplifier and filter characterization
• Clock and frequency stimulus generation
• Transient and fault-condition reproduction
• Recorded-waveform playback
• Automated functional testing
• Research and laboratory experiments

Sensor and Transducer Simulation

An AWG can reproduce the electrical output of a sensor without requiring the physical sensor or environmental condition to be present. This allows an automated system to apply repeatable normal, boundary and fault signals to an ECU, controller or acquisition system.

Verify that the generator can reproduce the sensor’s voltage range, source impedance, bandwidth and DC behavior. Bridge sensors, current loops, thermocouples and other specialized interfaces may require external circuitry rather than a direct voltage-generator connection.

Legacy PXI Signal Generator Replacement

Replacing an older PXI waveform generator with a newer PXIe model requires more than matching bandwidth. Differences in voltage range, output impedance, waveform memory, scripting, filtering and driver behavior can change DUT stimulus and test results.

Compare the following before approving a replacement:

• PXI or PXI Express slot compatibility
• Function-generator or AWG capability
• Output channel count
• Analog bandwidth and waveform rate
• DAC resolution
• Output range into high impedance and 50 Ω
• Output impedance and current capability
• Waveform memory
• Scripting and sequence behavior
• Streaming support
• Reconstruction-filter response
• Trigger and synchronization routes
• Front-panel connector and cable type
• NI-FGEN and application-code compatibility

Validated production systems should be requalified after a model change. A waveform that uses the same digital sample file can produce different analog results when generated by another instrument architecture.

PXI Signal Generator Procurement and RFQ Guide

When comparing quotations, confirm the exact channel configuration and part number. Check whether coaxial cables, auxiliary I/O accessories, calibration documentation and required software licenses are included.

Часто задаваемые вопросы

What is the difference between a function generator and an AWG?

A function generator creates standard mathematical waveforms from parameters such as frequency and amplitude. An arbitrary waveform generator reconstructs a user-defined sample record and can reproduce custom, recorded or nonstandard signals.

What is the difference between PXIe-5413, PXIe-5423 and PXIe-5433?

All three are 16-bit PXI Express AWGs available with one or two channels. The PXIe-5413 provides 20 MHz bandwidth, the PXIe-5423 provides 40 MHz plus scripting and streaming, and the PXIe-5433 provides 80 MHz bandwidth with more onboard memory.

What is the PXI-5404 best suited for?

The PXI-5404 is a single-channel DDS-based clock and waveform generator for repetitive high-frequency signals. It differs from the newer high-resolution PXIe AWGs intended for flexible multichannel arbitrary-waveform generation.

Can a PXI waveform generator replace an RF signal generator?

Only when its frequency range, output power, modulation and spectral performance meet the application. Microwave, wireless and calibrated RF tests normally require dedicated RF signal-generation hardware.

Why does the measured output voltage differ from the programmed value?

The programmed amplitude may assume a specific load impedance. Connecting a high-impedance load to an output configured for 50 Ω operation can change the measured voltage. Check the generator configuration, cable and DUT termination.

Can the output drive a speaker or actuator directly?

Not necessarily. PXI waveform generators provide precision signal stimulus but are not power amplifiers. High-current or high-power loads normally require a suitable external amplifier.

Can several waveform generators be synchronized?

Yes, when the modules support compatible clocks and trigger routes. Repeatable phase alignment may require a shared reference, synchronized triggers and instrument-specific synchronization procedures.

When is waveform streaming necessary?

Streaming is useful when the waveform is longer than onboard memory or must change continuously during generation. The controller, PXIe backplane, software buffers and generation rate must sustain the required data flow.

Related NI PXI Solutions

NI PXI Signal Generators from PXISOURCE

PXISOURCE supports engineers, laboratories, system integrators and procurement teams with PXI waveform-generator selection, chassis compatibility review, cable matching, software verification and legacy AWG replacement. Send the required waveform, bandwidth, voltage, channel count, chassis model and preferred hardware condition for a technically matched quotation.