What Is an Arbitrary Waveform Generator?
An arbitrary waveform generator is a signal generator that can generate signals with arbitrary frequencies and waveforms.
Function generators of the past could only output signals with a fixed pattern.
In contrast, waveform generators have increased functionality and are characterized by the ability to generate arbitrary signals that can be set by the user, even when complex waveforms are required. The most common method of generating arbitrary waveforms is to store digital waveforms in semiconductor memory and output them by D/A conversion.
Uses of Waveform Generators
Waveform generators are often used in the development and testing of electronic equipment. Systems and individual components are repeatedly tested using waveform generators for design, testing, and manufacturing.
For example, they are used in wireless communication applications involving intermediate frequency (IF) and radio frequency (RF) signals, as well as testing in physics fields such as quantum computing and spintronics.
Some waveform generators can generate waveforms at high speed, while others allow the user to freely define and output sequence, modulated, or pulse waveforms.
Principle of Waveform Generators
The most mainstream waveform generator used in the past was called a function generator (FG). In addition to sine and pulse waves, these waveform generators can also generate triangle, ramp, and noise waves. Although function generators can also generate simple arbitrary waveforms, they cannot sufficiently generate complex waveforms.
Waveform generators generally consist of a large waveform memory, a clock signal source, and a D/A converter. This allows the sample frequency in the clock signal source to be set arbitrarily so that all waveform data recorded in the waveform scale can be output without interruption.
Specifically, by replacing the waveform ROM portion with rewritable RAM in the digital direct synthesizer DDS method oscillator, the user can freely write waveforms. The DDS method consists of an accumulator with an adder and a latch, and accumulates the frequency setting value N in synchronization with the clock to obtain digital data in the form of sawtooth waveforms.
Other Information on Waveform Generators
1. Functions of Waveform Generators
Arbitrary waveforms include sine, square, triangular, and sawtooth waveforms, as well as waveforms with a time component such as continuous, single-shot, and intermittent waves.
Frequency is not only constant, but also has a function called sweep, which continuously changes the frequency. In addition, the amplitude can be generated arbitrarily from 10 mVp-p to 30 Vp-p.
2. How to Use Waveform Generators
Waveform generators have multiple output terminals, which are BNC terminals, making them resistant to noise and minimizing signal transmission loss.
The output impedance is 50 Ω, so care must be taken to attenuate the signal if the input impedance of the circuit to which it is connected is low. Each output terminal can output waveforms as desired.
They are also used for driving signals for various test equipment, such as changing the rotation speed of a motor or arbitrarily changing the vibration frequency of a vibration tester.
3. Waveform Generators With USB Connections
Recently, an increasing number of arbitrary waveform generators have USB ports. Waveform generators can be controlled via USB by setting arbitrary waveforms with a PC application.
USB is also used as a communication port for ON/OFF or frequency sweep by an automatic control program. Extensive control is possible, such as switching between sine, square, sawtooth, and burst waveforms, changing amplitude and duty, and frequency sweeping.