ARBITRARY WAVEFORM GENERATOR SIGNALS

Used to test various circuit topologies, an arbitrary waveform generator (or AWG) can be used as general-purpose function generator as well as a waveform generator. Let’s first address the difference between a signal generator, function generator, and an arbitrary waveform generator.

Signal generators produce high-fidelity sine wave signals that range from low frequencies to many gigahertz (GHz). Features of signal generators include attenuation, modulation, and sweeping.

Function generators are lower-frequency instruments which produce sine, square, pulse, triangle, and ramp waveforms from direct current up to a few megahertz (MHz) and usually cover a wide range of voltage.

Arbitrary waveform generators, which we’ll be focusing on below, are high-flexibility signal sources that can generate any arbitrary waveform constructed from point-by-point in digital memory, and these constructed waveforms are converted into analog signals with the AWG’s digital-to-analog converter (DAC), which operate at clock rates up to a few gigahertz (GHz). Because AWGs have built-in algorithms that generate standard functions, they can stand in as an ordinary function generator.

Types of Arbitrary Waveform Generator Signals

There are four categories of waveforms that an arbitrary waveform generator can create: standard and advanced functions, arbitrary waveforms, and waveform sequences. The standard functions category consists of pulse, ramp, sine, square, and triangle waveforms which are used in such applications as baseband, audio, sonar, ultrasound, and video components as well as circuits. Frequency response characterization, digital logic generation, device linearity characterization, and direct current-offset signal generation tests can be performed with an arbitrary waveform generator.

The majority of arbitrary waveform generators feature advanced functions including multi-tone, cardiac, noise, and much more that are used by specific industries for unique applications — e.g., cardiac and haversine signals are commonly used in medical device tests. Due to the abrupt transitions in the signal, standard pulse waveforms excite the device under test with extensive harmonic content; and other kinds of pulse waveforms have smooth transitions which shape the harmonic content for certain applications. Some examples are sinc and exponential pulses.

Sinc pulses, which are shaped with bandwidth-limited frequency spectrums, are used to characterize or excite communications channels that have limited bandwidth capability. Exponential pulses can simulate various physical phenomena, e.g., a resistor-capacitor charging circuit.