Waveform/Function Generators

What is a function / waveform generator?

A  function generator is electronic test equipment that generates standard waveforms, such as sine, square, ramp, or sawtooth waves, to a device under test (DUT). In circuit design and boards, testing often requires a controllable signal to simulate regular operation. Testing physical systems and transducers often requires stable and reliable signals ranging from microvolts to tens of volts or more.

By providing a stimulus or known input signal, we can see what happens to a device under different conditions. Does the DUT behave as expected? What kind of tolerance does it have before performance starts to break down?

You can evaluate the DUT’s performance by inputting a known-good signal into the DUT and monitoring the output. The waveform generator output must be clean and stable, and it should represent the real signals that the device’s final application will use. 

What is Keysight Trueform waveform generation technology?

Trueform waveform generation technology is an exclusive technology found in Keysight’s 33600A and 33500B Series Trueform waveform generators. Keysight’s Trueform technology represents the next leap in waveform generation technology, providing you with the best of both worlds: a predictable low-noise waveform with no skipped waveform points like PPC technology, at the price point of DDS technology.

What is the advantage of Trueform technology?

These advantages include the following: 

Lowest jitter 
With jitter as low as 1 ps, Trueform function / arbitrary waveform generators offer exceptional edge stability. You can even use them as a system clock for timing and triggering other instruments. With better jitter performance, you can place edges more accurately, helping reduce timing errors in your circuit design.

Lowest harmonic distortion
With a total harmonic distortion of just 0.03%, Trueform waveform generators offer up to 5x better fidelity than other generators. Clean, spurious-free signals don’t introduce noise or artifacts. You’ll see your design’s characteristics, not the waveform generator’s, in your measurements.

Non-aliasing 
Define any waveform shape and length using the Trueform arbitrary waveform capability. Play your signals as defined, at your exact sample rate, without missing short-duration anomalies that are critical for testing device reliability. Trueform never skips points and is always anti-aliased.

What is Keysight PathWave BenchVue Software?

The Keysight PathWave BenchVue software contains and hosts various applications. BenchVue applications enable you to control your test instruments and simplify your test processes. 

PathWave BenchVue software lets you connect, control, and capture data from your choice of an ever-growing list of supported Keysight instruments. Most function generators have PC application software that links to their instruments. Software typically eliminates the many issues around bench testing by making it simple to connect, control, and automate instrument test sequences.

How do you use PathWave BenchVue software in a function generator?

PathWave BenchVue software for waveform generators provides full-featured waveform-creation software. The software enables engineers to take full advantage of signal-generation capabilities and makes custom waveform creation fast and simple. 

PathWave BenchVue software is a PC application that provides easy-to-use creation tools, such as an equation editor and waveform math and drawing tools, that you can use to create custom signals. Its plug-and-play functionality enables you to connect your instrument to your PC and immediately begin controlling it in BenchVue.

When you open BenchVue and connect to your waveform generator, you will see a graphical instrument control window of your waveform generator. You can set up regular sine, square, ramp, pulse, triangle, noise, PRBS, and DC waveforms with desired parameters using the graphical user interface.

What is IQ modulation? 

In-phase quadrature modulation, or IQ modulation, is the dominant modulation scheme in communication applications. It is popular because of its efficient use of bandwidth, which continues to be a challenge in our data-hungry world. Testing with simulated IQ signals is critical because designers face a continual bandwidth crunch in a spectrum filled with interference.

For example, designers need to test their designs’ limits to ensure real-world performance. To do this, they must first generate an ideal signal to test the design’s ideal performance. Therefore, they must generate a high-quality, known-good signal.

You can simulate nonideal IQ signals by adjusting the gain balance between the two channels and the amplitude offset for each channel. You can even perform skew adjust to shift either the I or Q baseband signal in time with picoseconds of resolution. Some function generators allow you to perform advanced modulation to add noise, random jitter, or deterministic jitter to the signal.

Why is waveform sequencing important? 

Waveform sequencing lets you create multiple configured waveforms with several common segments. Sequencing lets you build long, complex waveforms using minimal instrument memory. With waveform sequencing, you can save memory by replaying different shorter waveforms at various locations in your signal as needed. 

Many tests require long waveform memory records. Eventually, the necessary record length may exceed the available waveform memory. Sequencing is a way to increase a signal’s length. In sequencing, different waveform segments repeat (or play back one after the other) through a user-defined sequence list.

Engineers looking to create a more efficient workflow to generate arbitrary signals can use waveform sequencing to develop a library of arbitrary waveform signals. Then they can reorganize the signals into a sequence to make a new signal.