What is a Signal Generator : Working & Its Applications

The signal generator is one kind of test equipment used to generate a waveform or electrical signal. They generate different kinds of waveforms based on the application. So these waveforms are mainly used in different systems like test instruments, development systems, etc. Signal generators are available in different forms where each type is used to generate different types of signals in different shapes like an audio signal, RF signal, pulse signal, analog, digital, etc. These systems are available from many years but,  present signal generators are very standard in terms of performance, facilities, etc. This article discusses an overview of what is a signal generator, working, and applications.

What is Signal Generator?

Definition: An electronic device or instrument that generates continuous and discrete signals like analog and digital is known as a signal generator. These systems are mainly used for testing, signal tracing, debugging, troubleshooting, amplifier response adjustment, etc. There is a variety of signal generators available in the market where each type includes modulation and amplitude property. So the output of the signal generator can be changed through setting its amplitude as well as frequency in the simulation process.

Signal Generator
Signal Generator

Block Diagram

The signal generator block diagram is shown below. In the block diagram, voltage controlled oscillator is an essential part because the input controlled voltage can be determined through the frequency of the voltage-controlled oscillator. So both the control voltage and VCO’s frequency are directly proportional.

Once the signal is given to the control input then it generates the oscillator frequency. Once the audio input signal is given to the control voltage then the frequency modulated signal will be produced using VCO. The signal generator generates the tone, waveforms in digital patterns, and arbitrary. Once the signal generates an unmodulated signal, then these are known for producing continuous wave signals. So it generates a square wave modulated signal, complex and triangular waves, etc.

Block Diagram of Signal Generator
Block Diagram of Signal Generator

For FM, the circuit of the modulator can be located after the voltage controlled oscillator. So this will change the output voltage of VCO through generating the AM output signal. The receiver can be tested by using the properties of signals like stability and accuracy.

Signal Generator Circuit

To check the failure part of any electronic circuit, a signal tracing technique is used. This technique is used commonly in audio electronics for troubleshooting. This method is used by adding a source of the signal at one end & the response can be checked at the remaining end, wherever the signal is transferred among these two ends & the segment between these ends is working fine.

Circuit Diagram
Circuit Diagram

The simple circuit of the signal generator is shown above. This circuit can be designed with a resistor and a capacitor so that a simple oscillator can be formed. This oscillator generates a harmonic-rich signal form for signal insertion.

Types of Signal Generators

Signal generators are classified into different types based on the capacity as well as its functionality. These are available in different dimensions, designs as well as parameters. So these generators are used for different purposes. Each signal generator can make limitless signals to reach the debug challenges.

Arbitrary Waveform Generators

These generators are used to generate arbitrary streams for digital data. So the shape of these signals cannot be stable. This generator includes two separate output channels used for stimulating two systems instantaneously. The main function of this generator is to activate a system using a complex signal. This generator includes a display to display a precise arbitrary waveform so that it helps to keep away from the possibility of mistake when choosing waveform from system memory. The bandwidth of these generators have limited and compared with function generators, these generators are expensive. These generators are used in communication, semiconductor component, etc.

RF Signal Generators

This generator is designed to generate signals like the phase-locked loop (PLL) & direct digital synthesis. In most of the signal generators, PLL is used for providing accuracy as well as the stability needed for the system. These generators produce analog signals in their frequency range.

The microwave & RF generators are approximately similar apart from they have a diverse range of frequency. But as compared with RF generators, the frequency range of microwave generators has a high range of frequency. RF signal generators are mainly used to test the systems, broadcasting of audio & video, electronic warfare, radar, satellite communication, etc. These generators are available in three forms like analog, vector, and logical.

Audio Signal Generators

These generators play a key role in generating audible signals which range from 20 Hz – 20 KHz. These generators are used in audio systems for checking its frequency response as well as measurements of distortion. Using this generator along with a simple circuit, very little distortion can also be measured. The harmonic distortion levels of this generator are less. The applications of these generators are electronic labs for various purposes. These generators use complex techniques for generating audio signals.

Video Signal Generator

This kind of generator mainly used to generate video signals. The main factor-like synchronization will affect the quality of video on TV, so the output signal of the video generator normally includes synchronization signals. These signals contain horizontal & vertical synchronization.

Function Generator

The function generator mainly includes an oscillator and the main function of this type of generator is to generate simple recurring waveforms like sine, square, triangular, and sawtooth. At present, these generators may utilize digital signal processing methods for producing digital waveforms & converts these signals from digital to analog. There are a variety of these generators are available like a black box including USB interfaces, applicable in instrumentation bus, etc. The applications of these generators are in the education field, electrical & electronic device repair, etc

Pulse Generator

The pulse generator is used to generate the waveforms in the pulse form. The pulse generated by this generator includes variable delays, variable rise as well as fall times. Pulse signals are frequently required while testing a variety of analog or digital circuits.

Signal Generator Formats

Signal generators are accessible in different formats similar to other types of test instruments. These formats mainly depend on the specific type of generator however there are various options are available like instrument card for rack test, bench test device, USB based signal generator, and use the waveform generated from the computer.

There are different formats that are available for these generators based on the physical format of the device. If the user device is stand alone, then the bench test instrument is the perfect route, except for systems & regions where PCs are obtainable.


The uses of the signal generator include the following.

  • An arbitrary waveform generator is used in test & high-end design applications
  • RF & microwave signal generators mainly used in components testing, test systems, and receivers in an extensive range of applications like WiFi, cellular communications, radar, GPS, WiMAX, broadcasting of audio & video, satellite, electronic warfare, etc.

Thus, this is all about an overview of the signal generator. The frequency characteristics of the signal generator are most important while searching for these generators like the range of frequency, the resolution of frequency, highest input channels, speed of switching & accuracy of frequency. Similarly, there are some specifications that need to consider while selecting these generators such as Host connections, user interface, storage, memory, a computer bus, etc. Here is a question for you, what are the advantages of a signal generator?