Function Generator Tutorial: Definition, Block Diagram and Components

Do you want to learn more about the function generators and how they work? How do you draw a function generator block diagram? Let's give this guide a read!


A function generator is a device capable of generating different functions or waveforms in a single shape device. These waveforms include sine, sawtooth, square, and pulsed waves.

In this article, we will talk about the function generator, its waveforms, and its applications through block diagrams.

In this article
  1. What is a Function Generator?
  2. The Waveforms in a Function Generator
  3. Function Generator Block Diagram
  4. The Controls of the Function Generator
  5. How to Make Such a Block Diagram?
  6. Conclusion

What is a Function Generator?

The function generator is a test instrument that can generate different waveforms, i.e., sine, square, and triangular waves. You can vary the length and frequencies of the applied waves through the function generator. However, you would be able to generate waveforms that are built into the function generator.

The range of frequencies used in the function generator is 0 HZ to 100KHZ. However, for industrial instruments, this range is relatively high. Modern-day oscilloscopes use a function generator, making them more functional to provide better results.

The Waveforms in a Function Generator

Sine waves

Sine or sinusoidal waves are among the most essential waveforms a function generator creates on screen. It is used to test instruments that need a single frequency. Meanwhile, the other waveforms use harmonics as well.

how sine waves are represented

The sine wave is used in many electronic circuits. It provides basic information about the defects in an electronic machine or analog systems, as a single frequency is needed to find results.

Square waves

The logical circuits use these square waves, and the signal is moved from high to low levels in a circuit. While using these waves, it is essential to note that the rise and fall time for the edges is faster. The output shown on the function generator is fast, so we need to adjust it accordingly.

square wave in function generator

The issue comes when the edges are not fast enough and don't meet the requirements of the logic circuit. To overcome this issue, a buffer is placed at the input to make the edges faster.


A pulse is another type of waveform that is generated through a function generator. There is no significant difference between the square wave and pulse except for the mark space ratio. The mark space ratio of 1:1 is used in many electronic circuits.

pulse in function generator

A function generator capable of producing the pulse wave makes the work easier. It automatically generates the mark space, neglecting the original mark space in the instrument. However, the speed of the rising and falling edges matters a lot. It needs to be faster for the function generator to catch it.

Triangular Wave

Operational amplifiers use this form of the function generator, which acts as an integrator. The waveform moves between high and low points.

triangular shape waves in function generator

These waveforms are used to test amplifiers as the distortion and clipping are better seen through triangular waveforms than sine waves.

Sawtooth Waves

It is a triangular wave with faster rise and slower fall points. This happens only when you change the charge rate for any integrator's rise and fall elements.

how to represent sawtooth waves in function generator

The sawtooth waveform is used mainly in cathode ray displays with a voltage that increases slowly to help get the scan. A faster flyback is needed to get back to scan, so the waveform seems to be like a sawtooth wave.

Function Generator Block Diagram

Here, we have a block diagram for working a function generator where frequency is managed by changing the current by two supplies. These currents drive the integrator, and the generator receives multiple output waveforms.

how to draw block diagram for function generator

The voltage provided in the system regulates these current supplies. The current supply provides a linear current to the integrator so that a smooth waveform can be generated. When there is a change in current, the waveform goes upward or downward according to the increase and decrease in the value.

The current supply two in the diagram provides the reverse current to drop the wave. There is an offset value till the reverse current flows in the circuit; after that, the circuit automatically changes the state and uses supply one current again.

The output of the integrator is a triangular shape when the frequency is dependent on the constant current supply (current supply 1).

A system operating at the same frequency will generate the square wave at the comparator output.

The amplitude of the output waves is changed through the resistance diode shaping circuit, and we get a smoother Sinusoidal waveform, keeping the distortion level below 1%.

The Controls of the Function Generator

There are four basic controls on which a function generator operates.


Frequency is one of the most important controls of the function generator. Through this control, the waveform is repeated and shows the properties of the devices.

Type of Waveform

This control lets you generate waveforms like sine, square, or triangular. Different frequencies and voltages may provide different waveforms. However, the function generator will only produce waveforms that are programmed into its system.


This control helps vary the voltage in the circuit and moves from 0V to the higher values that we set for a device.

Duty Cycle

This control changes the voltage ratios for a high value and a low value for a square waveform. When pulse or triangular form is needed, the duty cycle ratio is changed to a 1:1 ratio with equal rise and fall times.

How to Make Such a Block Diagram?

Block diagrams are meant to ease the complexity of a system and make it more understandable for the engineers. Here is how you can create a block diagram.

Method 1: Starting From Scratch

Before you start designing your block diagram, it is essential to know what your needs are. You need to know about the components of your diagram and the starting and ending points.

Input and Output

Draw blocks for input and output in your diagram. We are going to take an example for the block diagram. The Antenna is the input device, and the loudspeaker is the output. Let's add the inputs and outputs in the diagram.

start with adding inputs and outputs in the block diagram

Drawing Components of the Diagram

You need to add a few other blocks to add components to your diagram. Fill the blocks with proper labeling to make it easier for a newbie to understand.

add blocks in the diagram with labels

Draw a Relationship with Clear Directions

Now, add relationships between the components of the diagram. The direction of the diagrams needs to be correct. You can add colors to give your diagram an extra glance.

add relationships among the components of the diagram

Method 2: Starting with a Template

Step 1: Click the template below to download it. You will be able to edit this file in your system online. If you need something else, you can choose different templates.

choose a template from the eddx template community

Step 2: Customize the diagram and add or remove any unwanted components. In this example, the fuel storage turbine is drawn to see the amount of storage we have and give information back to the control room. We have added components like the camera, images, and everything from the template and added out components with ease.

block diagram example with the help of a template


A function generator is widely used to check an instrument's properties, defects, and work. The waveforms generated through the function generator tell us many things about the instrument. The function generator block diagram helps us understand the workings of the generator. What components are needed to form these diagrams?

Function generator block diagrams could get tedious to make sometimes. So, a template could easily do it for us. EdrawMax helps us quickly generate these diagrams by providing all the tools needed to make them. So, I hope you learn a lot about function generators and how they help you get the most valuable information about an instrument. The function generator block diagram is the one describing its functionalities. So, to create your diagram for any circuit, EdrawMax could help you. Try it for better understanding.

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Edraw Team
Edraw Team Apr 15, 24
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