Signal Generators and Waveform Generators

Signal generators and waveform generators are used to test and align all types of transmitters and receivers, to measure frequency and to generate a signal, waveform or noise source. Signal generators can use AC energy, audio frequency (AF) and radio frequency (RF) to function.

They are also used to troubleshoot various electronic devices and to measure frequency. The function of a signal generator is to produce alternating current (AC) of the desired frequencies and amplitudes with the necessary modulation for testing or measuring circuits. It is important that the amplitude of the signal generated by the signal generator be correct. In many signal generators, output meters are included in the equipment to adjust and maintain the output at standard levels over wide ranges of frequencies. When using the signal generator, the output test signal is connected to the circuit being tested. The progress of the test signal can then be tracked through the equipment by using electronic voltmeters or oscilloscopes. In many signal generators, calibrated networks of resistors, called attenuators, are provided. Attenuators are used in signal generators to regulate the voltage of the output signal. Only accurately calibrated attenuators can be used because the signal strength of the generators must be regulated to avoid overloading the circuit receiving the signal.

Signal generators and waveform generators typically come as a portable or benchtop instrument, a fixed instrument, or a PC-based instrument or module.  Common generator types include continuous wave, function, pulse, signal and sweep. A source that can produce a sine wave is referred to as a CW source.  The frequency and amplitude of the sine wave can be set in most CW sources. Function generators create square waves by applying a bipolar sine wave to a comparator’s input. A pulse is a short burst of signal(s) generated by instrument. Signal generators output signals, or sine waves that carry information.  There are numerous methods for adding information to sine waves.  Basic signal generators have frequency, amplitude and phase modulation capabilities.  More advanced signal generators have pulse and IQ modulation capabilities. A swept source adds the ability to automatically vary the output frequency or amplitude of a sine wave over a range of frequencies or amplitudes in a controlled manner.

Frequency characteristics that are important to consider when searching for signal generators and waveform generators include maximum input channels, frequency range, frequency resolution, frequency accuracy, and switching speed. The maximum input channels refer to the maximum number of all analog input channels, general and specific types. The frequency range specifies the range of output frequencies the generator can produce. The frequency resolution is the smallest frequency increment the generator can produce.  The generator’s internal clock determines the frequency accuracy.  It is a measure of how accurately the source frequency can be set.  Operation features to consider include on board reference, on board oscillator, reverse power protection, and battery powered.  An on board reference is a source of information, usually referring to the clock, which supplies timing information. An oscillator creates the basic electrical fluctuation (AC) that is used to create the waveforms. Reverse power protection prevents signals traveling the wrong direction from damaging the source.

Additional specifications to consider when searching for signal generators and waveform generators include user interface, connections to the host, memory and storage, computer bus, display options, and environmental parameters.

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