The signal generator is a kind of test equipment used to generate waves (sine wave, square wave, triangular wave) or electrical standard test signals. It is also called an oscillator because it generates periodic signals. It can provide different types of waves depending on the application, these waves are mainly used in test instruments, development systems, etc. There are different types of signal generators available, each type is used to generate different kinds of signals such as audio signals, RF signals, pulse signals, analog, digital, etc.
What is signal generator?
The electronic device or device which generates continuous and discrete signals like analog and digital is known as a signal generator. Which are mainly used in testing, signal tracing, debugging, troubleshooting, amplifier response adjustment, etc. These include modulation and amplitude properties. In the simulation process, one can change the output of the signal generator by setting its amplitude as well as the frequency.
Block Diagram of Signal Generator
In the signal generator block diagram, the voltage controlled oscillator remains an essential part. Since the input voltage can be determined through the frequency of the voltage-controlled oscillator, then the control voltage and the frequency of the VCO are both inversely proportional.
Once the signal is supplied to the control input, it starts generating the oscillator frequency. And once the audio input signal is provided to the control voltage, the frequency modulated signal will be produced by the VCO. The signal generator can generate tones, waveforms and arbitrary in digital patterns. Once the signal is produced an unmodulated signal, it produces continuous wave signals. certainly It produces signal waveforms like a square wave modulated signal, complex and triangular waves etc.
For FM frequency modulators, the modulator’s circuit can be set after a voltage controlled oscillator, then it will change the output voltage of the VCO by generating an AM output signal. The receiver can be tested using the properties of the signals such as stability and accuracy.
Circuit of Signal Generator
Signal tracing techniques are used to locate the failed part of any electronic circuit. This technique is commonly used for troubleshooting audio electronics. In this method, the source of the signal is connected on one side and the response is checked on the other side. So when the signal is transferred between these two sides then the section between the ends is working fine.
The simple circuit of a signal generator is designed by a resistor and a capacitor to form a simple oscillator. This oscillator produces a harmonic-rich signal form for signal entry.
Types of Signal Generators
Signal generators are classified into different types on the basis of capacity and function. These are available in different dimensions, parameters with designs. Generators are used to generate an infinite number of signals to reach various purposes and debug challenges.
- AF Sine and Square Wave Generator.
- Arbitrary Waveform Generator.
- RF Signal Generator.
- Audio Signal Generator.
- Video Signal Generator.
- Function Generator.
- Pulse Generator.
AF Sine and Square Wave Generators
The AF signal generator can produce either a sine wave or a square wave in a range of audio frequencies depending on the requirement. AF is called sine and square wave generator. The range of audio frequency is 20Hz to 20KHz.
There are mainly two paths in the above block diagram. They are upper path and lower path. The upper path is used to generate the AF sine wave and the lower path is used to generate the AF square wave.
The Wien bridge oscillator produces a sine wave in the range of audio frequencies. Depending on the requirement, the outputs of the Wien bridge oscillator can be connected to the upper path or lower path by a switch.
The upper path consists of blocks such as a sine wave amplifier and attenuator. If the switch is used to connect the output of the Wien bridge oscillator to the overhead path, it produces the desired AF sine wave at the output of the overhead path.
Arbitrary Waveform Generator
This generator is used to produce arbitrary streams of digital data. Hence the shape of the signals cannot be constant. This generator includes two separate output channels that are used to excite the two systems immediately. Its main function is to activate the system using a complex signal. This generator includes a display to display a precise arbitrary waveform, thereby helping to avoid the possibility of mistakes while selecting the waveform from the system memory. The bandwidth of this generator is limited as compared to the function generator. These generators are expensive. This generator is used in communication, semiconductor components etc.
RF Signal Generator
This generator is designed to produce phase-locked loop (PLL) and direct digital synthesis signals. In most signal generators, PLLs are used to provide the accuracy and stability required for the system. This generator can generate analog signals in its frequency range.
Microwaves and RF generators are almost the same, apart from having a diverse range of frequencies. But compared to RF generators, microwave generators provide a higher range of frequencies in the frequency range. It is mainly used in systems testing, audio and video transmission, electronic warfare, radar systems, satellite communications, etc. These generators are available in three forms, analog, vector and logical.
Audio Signal Generator
This generator produces audible signals ranging from 20 Hz – 20 kHz. These generators are used in audio systems to test the measurement of distortion along with the frequency response. By using this generator with a simple circuit, very little distortion can be measured. This generator has a low level of harmonic distortion. These generators are used in electronic laboratories for various purposes. These generators use complex techniques to produce audio signals.
Video Signal Generator
This type of generator is mainly used for video signal generation. The main factor in this generator affecting the quality of the video on the synchronization TV is that the output signal of the video generator normally includes synchronization signals. These signals have horizontal and vertical synchronization.
Function generators mainly consist of an oscillator and the main function of this type of generator is to produce simple periodic waves such as sine, square, triangular and sawtooth. Currently, these generators use digital signal processing methods to produce digital waveforms and convert these signals from digital to analog. There are many types of these generators available, which are implemented in black boxes, instrumentation buses including USB interface. These generators are used in the education sector, electrical and electronic devices, etc.
As per the above block diagram there are two current sources, namely upper current source and lower current source. The two current sources are controlled by a frequency-controlled voltage.
Pulse generators are used to produce waves in the form of pulses. The pulse generated by this generator includes a variable delay, and a time to fall with variable rise. Pulse signals are needed when testing a variety of analog or digital circuits.
Signal Generator Formats
Signal generators are available in a variety of formats, similar to other types of test equipment. These largely depend on the specific type of generator, although there are many different options available for rack testing such as equipment cards, bench test devices, USB-based signal generators and the use of computer-generated waveforms.
There are different formats available for these generators depending on the physical appearance of the device. When user devices are stand-alone, the bench test instrument is the right way to go, except in systems and areas where PCs are accessible.
Applications of Signal Generator
The Following are the uses of signal generator.
- An arbitrary waveform generator is used in test and high-end design applications
- RF and microwave signal generators primarily find use in components, test systems and receivers in a wide range of applications such as WiFi, cellular communications, radar, GPS, WiMAX, audio and video transmission, satellite, electronic warfare, etc.