In the field of electronics engineering, a signal generator is an essential tool. This tool could help an engineer with system design by generating a waveform or electrical signal. Therefore, these gadgets are used in a wide variety of labs and workshops for research and development. Audio, radio frequency, pulse, analog, and digital signals are just few of the many that may be generated by signal generators. Signal generators have been around for a while, but the capabilities of modern ones are quite remarkable. Learn more about signal generators and what to look for in one by reading this article.
Several DIY signal generators, such as the Waveform Generator utilizing Arduino, are available on our website if you’re interested in constructing your own.
Brief Description about Signal Generator’s Working!!!
There is a large variety of signal generators available, each with its own set of features and requirements, but they all perform the same basic function: generating a wide range of signals for use in testing, debugging, and improving electronic equipment. The next paragraphs elaborate on the simplified Block Diagram of a signal generator shown in the following diagram. Adjusting the output signal’s frequency, amplitude, and waveform are all handled by separate controls in the RF signal generator block diagram.
Without the Voltage Controlled Oscillator (VCO), signal generators would be useless. Changing the DC voltage fed into the VCO will cause a corresponding change in output. The voltage fed to the oscillator determines the frequency produced by the VCO. The output of the oscillator is routed through a buffer amplifier before being sent to the frequency divider. The signal generator can function independently from the load thanks to the buffer amplifier. An output amplifier is used to amplify the signal from the buffer amplifier even further. An attenuator reduces the voltage of the signal before it reaches an output meter, which measures the strength of the signal and provides feedback for further adjustment.
Types of Signal Generators
A signal generator is a piece of testing gear that may generate a steady or intermittent signal. It is possible to classify signal generators according to the types of signals they produce and the frequency bands in which they operate. The output of the signal generator can be tuned in real time by modifying the signal’s amplitude and frequency.
Below are summaries of some common kinds of signal generators. Function generators, radio frequency (RF) signal generators, arbitrary waveform generators, analog signals, digital signals, logical signals, video signals, etc.
Functional Signal Generator
An extremely common form of signal generator is the “function generator.” It may produce periodic waves in a variety of shapes, including sinusoidal, sawtooth, square, triangular, and pulse. A circuit known as an electronic oscillator generates these pulses. Most current devices use digital signal processing (DSP) to generate signals, which are then converted to an analog form for use in the device.
The function generator’s ability to add a DC offset to the signal is a key feature that makes it a valuable testing tool. Although most function generators run between 100 kHz and a few MHz, high-end models are capable of generating signals in the gigahertz range.
Common applications for function generators include educational institution laboratories, electrical and electronic equipment repair shops, and stimulus testing. The following is a block diagram of the function generator.
Radio Frequency Signal Generator
Radio Frequency Signal Generator or RF signal generators are the most essential testing equipment where radio frequency or microwave testing and development is required. Similar to other signal generators, most RF generators do not have measurement capability, they are just used for producing controlled signals with variable frequency, amplitude, and modulation which can be used to check the response of circuitry in order to debug or modify the circuit.
The power output of a RF signal generator is defined in terms of dB relative to 1milliwatt (dBm). The most common power output available in RF signal generator is +13dB. The power level in dBm to power level in milliwatt is given below.
Audio Frequency Signal Generator
An Audio Frequency (AF) signal generator is a signal generator that can produce signals in the AF frequency range. The 20 Hz to 20 kHz range is where sound frequencies live. Here is a block schematic of a basic AF signal generator that produces either sine waves or square waves:
Despite its primary function—testing the responsiveness of audio gear—audio frequency generators are also used to measure distortions in other types of equipment, as even the simplest audio signal generator may generate aberrations as small as 0.0001%.
Arbitrary Signal Generator (ASG)
Modern function generators take the form of arbitrary signal generators. Like function generators, ASG’s output is determined by the values we feed into it, be they digital or analog. Waypoints are the values used as input. Therefore, arbitrary signal generators are the most flexible signal generators since they can produce any desired waveform.
Vector Signal Generators
Signals can be digitally modulated, and vector signal generators (sometimes called digital signal generators) are capable of creating such signals. They’re put to work in the production of radio frequency signals with sophisticated modulation schemes like BPSK, QPSK, QAM, and so on. Military and civilian communication systems alike rely on sophisticated testing equipment; for example, advanced vector signal generators can produce signals for widely used technologies like GSM, W-CDMA, LTE, and Wi-Fi, as well as for the highly secure military communications systems like JTRS.In the following illustration, we see a vector signal generator:
Video Signal Generators
The generation of video waveforms requires a specialized sort of signal generator called a video signal generator. These gadgets help technicians calibrate TVs and other video systems by simulating common problems. Synchronized signals in the form of horizontal and vertical pulses, as well as color burst signals, can be generated by a VSG.
The most common applications for video signal generators are in the research and development, testing, and calibration of video technology.
What to consider while selecting a Signal Generator?
We can pick from a wide variety of signal generators on the market. There is a wide range in price for signal generators, from those that cost less than $50 to those that cost tens of thousands of dollars. So, we need to know our precise needs, the kind of signal we require, and other criteria like frequency and precision before settling on a model. In the following paragraphs, I will give a high-level overview of the criteria we must meet before making the acquisition.
Waveforms and Modulations
The waveforms that a signal generator is capable of producing are the most crucial feature to evaluate before beginning our search. As was previously mentioned, function generators can produce standard signals like sinusoidal waveforms, step signals, saw teeth, etc., but an Arbitrary Signal Generator may be necessary for more complex or individualized signals. Therefore, knowing what kind of signal you need from a function generator is the primary factor in making a purchase.
Frequency Range
As was previously said, signal generators are a type of testing equipment used to verify the functionality of electronic circuits. Depending on the circuits we need to test, we must choose a suitable signal generator. While a function generator can produce signals up to a few megahertz, a specialized RF and microwave signal generator capable of producing frequencies in the range of a few GHz is required to test more complex RF circuits. Therefore, we must ensure that the frequency range of the signal generator we choose is suitable for our needs.
Resolution
In terms of measurement systems, resolution is a crucial factor. It is a measure of the minimum amplitude at which an electronic device can differentiate between 2 points in a waveform. It is the smallest value that can be read by our instrument. The smaller a value may be displayed on a measuring device, the higher the resolution of the instrument must be.
Sampling Rate
The number of samples taken in a given amount of time is known as the sampling rate. Accuracy and resolution improvements are directly proportional to the sampling rate, hence increasing it is a must. If the sampling rate is larger than twice the maximum frequency, then a flawless reconstruction of the original signal is possible, as stated by the Nyquist principle.
Phase Locking Mode
Working with radio frequency signals necessitates a signal generator with phase-locking functionality. When working with high-frequency circuits, phase locking to a local oscillator or clock is a typical practice.
Output Impedance
The signal generator’s output impedance is a crucial factor to consider. Using the signal generator as a voltage source requires the output impedance to be minimal, while connecting the signal generator to an RF circuit necessitates a high output impedance that is compatible with the impedance of the transmission line.
Conclusion
Electronics engineers rely heavily on signal generators because of their usefulness in circuit design and troubleshooting. Different kinds of signal generators can be purchased online. When choosing a signal generator, it’s important to consider the electronic circuits that will be tested, as well as the parameters such as resolution, sample rate, output impedance, frequency, waveform generation capability, etc. If you have any further questions concerning signal generators, or if this post has helped you learn something new.