AWG Basics-1

April 23, 2020

Many electronic designs feature the ability to monitor or measure input signals and then perform another

task or function based on that input signal. A simple example could be a circuit that looks for an input

voltage to exceed a speciﬁc amount and triggers another action after it occurs. In such cases, having the

ability to conﬁgure and deliver a known or simulated signal can be a critical addition to testing the

performance of the design. Unlike acquisition instruments that measure a signal, an input signal can be

created using a signal source. This can be as simple as a DC power supply or as complex as a digital

communication signal delivered by an RF Vector Source. One of the most ﬂexible and useful signal sources

available today is the Arbitrary Waveform Generator (AWG).

In this series of notes, we are going to introduce some of the features that make AWGs so useful and

explain in a bit more detail just how they work.

What types of signal sources are on the market today?

Let’s start with the basics. Most sources can be divided into two broad application categories: Digital and

Analog.

Signal sources specially created for digital applications are often called logic sources. Logic sources can be

roughly divided into two categories: Pulse and pattern generators. A pulse generator can output square

waves and pulse streams. The output frequency of the pulse generator is generally very high and it is

often used to test digital devices. A pattern generator, also known as a logic source or data generator is a

bit unique. This kind of instrument generally has 8 or 16 output channels, but higher channel counts are

available. Each output can generate various types of synchronous digital pulse streams, generally from a

low to a high voltage value, 0-5 V for example. Pattern generators are often used as excitation signals for

computer buses, digital telecommunications units, and other serial communications links.

Analog generators typically have one or two outputs and feature a wider array of possible output levels,

wave shapes, and frequencies than digital sources. More specialized forms of analog generators also exist

for high frequency applications. We aren’t going in to further detail about them here, but some common

types include RF signal generators, microwave signal generators, and baseband signal generators.

In this article, we will concentrate on the most general purpose signal source, the arbitrary waveform

generator. In simple terms, an arbitrary waveform generator is a device that creates an output signal

based on a digital waveform ﬁle, created from a series of discrete output sample points, and “plays” the

ﬁle contents at the source output of the generator. Using this sampling principle, waveforms of almost any

type can be created, including basic waveform functions like square, sine, and ramping output shapes.

Arbitrary waveform generators can also have more advanced functions like output triggering and system

clock signals for synchronizing external instruments. One such generator is the SIGLENT SDG2000X series

function / arbitrary waveform generator shown in Figure 1 below.

Figure 1: SIGLENT SDG2000X function / arbitrary waveform generator

What is the waveform generator used for?

As mentioned previously, most arbitrary waveform generators include basic function types like sine,

square, and triangle waves. In addition, waveform generators can also generate analog and digital

modulation signals, supporting the output of linear / logarithmic sweep signals and pulse trains. Many of

SIGLENTs SDG series of generators support AM, FM, PM, FSK, ASK, DSB-AM and other analog and digital

modulation functions and include a large standard library of included arbitrary waveform functions.

There are hundreds of applications for waveform generators, but in the ﬁeld of electronic test and

measurement, the application range can be basically divided into three types: inspection, veriﬁcation, and

limit / margin test. During the commissioning phase of a design, the engineer needs to test the parameters

of the product to verify whether the product meets the relevant design speciﬁcations. In this process, the

waveform generator can be used to source the signal speciﬁed in the design speciﬁcation. Here, the

Engineer can observe the response of the design, compare the results with the speciﬁcations, and perform

any adjustments that may be necessary with the design. In addition, newly developed industrial control

modules, data conditioning modules, and others all need to use waveform generators to test their linearity

and monotonicity through exhaustive testing. In many occasions, the waveform source needs to add a

known, repeatable distortion in quantity and type to the signal it provides. With many generators, you can

add noise and programmed distortion to the signal and directly test the ability of the design to handle

speciﬁc real-world signal issues.

What are the main indicators of the waveform generator? What do these indicators mean?

Oscilloscopes have common banner speciﬁcations: Bandwidth, memory depth, and sampling rate. When

we select a suitable oscilloscope, these three major indicators are often our ﬁrst consideration.

Does the waveform generator also have the so-called three major indicators? The answer is yes. In the

category of waveform generators, there are also concepts of bandwidth, sampling rate and memory depth.

Bandwidth1.