Last Updated on July 31, 2023 by Kevin Chen
Image source Freepik
An Operational amplifier (op-amp ) is an analog electronic component that accepts differential voltage as the input signal and produces a single-ended voltage as the output signal. It is quite a common feature in most analog integrated circuits whereby it is mainly used for signal processing functions.
A typical operational amplifier has three terminals two of them are high-impedance inputs and the other single output is the low-impedance output terminal. The inverting input terminals are denoted by the negative (-) sign while the non-inverting input terminal is denoted by the positive (+) sign. In this configuration, the Op-amp will be able to amplify the voltage between the input and the output terminals.
Operational amplifiers have quite a wide range of applications in the modern world of electronics. As long as the application will entail the processing of analog signals, then you should expect to find the relevance of the op-amp in it. Some are used in power management devices, audio devices, and communication devices among many others.
Keep reading as we discuss all the basics that you should know about operational amplifiers. In case you are planning to buy op-amps, I will also give you tips on how to choose the right one for your application.
Types of operational amplifiers
There are four major classes of the operational amplifiers. These are;
Voltage amplifiers
This type of op-amp is designed to accept the input voltage and still produce the output voltage signal. Technically, it is the most common type of op-amp due to its primary role of amplifying voltage in the circuit.
What is the amplification level of the voltage amplifier? Usually, the amplifier will take a difference between the inverting and non-inverting inputs to give an output voltage that is directly proportional to the input voltage.
Check the image below for clarification
Image of voltage amplifier source CircuitBread
One distinct feature of voltage operational amplifiers is high voltage gain. This simply means that the amplifiers are designed to accept a very small input voltage and amplify it to extremely high levels. This feature alone makes this op-amp suitable in most application areas where the input signal is very low yet the same power source is needed for running high loads.
Current operational amplifier
Unlike in the previous type of op-amp, this one focuses on the electric current. It receives the input current signals and amplifies it to the desired levels. In most cases, the output current will be higher than the input current.
Current op-amps have slightly different characteristics and properties from the voltage operational amplifiers. They also have fewer application areas than the voltage op-amps.
Transconductance amplifiers
The operational transconductance amplifiers (OTA) are used for converting the input voltage into the output current. They are usually used as additional input accessories for controlling the current amplifiers. Additionally, they have a high impedance differential input stage which in most applications us used with negative feedback.
What separates the transconductance amplifier from the rest of the operational amplifier? First, its output is current while the standard output for most op-amps is voltage. Secondly, it uses an open-loop in the linear applications.
Transresistance amplifier
This type of operational amplifier converts the current input to the voltage output. In most applications, this type of op-amp is referred to as a voltage-to-current converter (V to I). The performance and efficiency of this amplifier is usually rated in terms of resistance.
Now that you know the different types of op-amps, you can make smart decisions about which type will be suitable for your application. All you need is to outline their functions and properties.
Main characteristics and parameters of the operational amplifiers
Let’s look at some of the main properties and parameters that define the operational parameters.
Open-loop gain
In an operational amplifier, open loop gain refers to the gain that the circuit achieves in the absence of feedback. As the name suggests, the feedback or loop of the circuit is left open. The value of an open loop should be very high for the op-amp to be relevant in its application area. It is only in voltage comparators that the open-loop gain is allowed to be relatively lower than the expected value.
One of the main reasons why the open-loop gain should be high is to guarantee stability in the circuit. An open-loop gain that is as high as 10,000 will ensure that all the other factors that affect the behavior of the signals such as temperature and humidity remain stable .
Input impedance
Operational amplifiers tend to have very high input impedance, which is basically the resistance value to the flow of current between positive and negative terminals of the circuit. It is calibrated in ohms. The ideal input impedance of the op-amp should be high towards the infinity so as to prevent any possibilities of loading the sources. After all, electric circuits that have high input impedance tend to draw minimal current which will eventually affect the value of the output voltage. On the other hand, low input impedance will force the amplifier to draw more electric current.
Keep in mind that the input impedance does not entirely depend on the voltage of the DC. The placement and arrangement of electronic components around an op-amp has a direct impact on the value of the input impedance.
Output impedance
This is another key parameter that you should pay attention to when buying operational amplifiers for your application. It is the resistance value to the flow of electric current from the circuit to the load. In our case, the current or signal is flowing from the amplifier to the device that is connected to the output terminal.
Should the output impedance of an operational amplifier be low or high? It should be not only very low but zero. Keep in mind that the output current from the op-amp will determine the behavior of the load. By having a low resistance value, it means that the load will operate smoothly and effectively without any interference.
Gain bandwidth product (GBP)
This is another vital property of the operational amplifier that you should know before buying. The gain bandwidth product refers to both the gain and bandwidth of the op-amps when it is in operation. The value of GBP should remain constant throughout the operation of the amplifier in a circuit.
The value of the gain bandwidth product is obtained by measuring the frequency point at which the gain of the operational amplifier reaches the unity. The GBP will eventually determine the performance and as well as the reliability of an operational amplifier.
Other parameters that deserve your full attention include voltage, current capacity, offset voltage, and noise level among others. You should pay attention to these parameters when designing the circuit as they will determine the overall performance of the operational amplifier.
Advantages of operational amplifiers
Why are op-amps used in their various application areas? Well, here are the top benefits of operational amplifiers.
- Flexible and versatile: Operational amplifiers come in the form of integrated circuits. This implies that you can easily integrate an op-amp in any application and it will function perfectly. All that you need to look at are the technical specifications of the operational amplifiers as we have discussed above.
- Low output impedance: This is one of the properties of the operational amplifiers. The main advantage that comes with this is the ability of the amplifier to run and control high loads without enduring major voltage drop since the output current will not encounter serious resistance. This attribute also enhances the accuracy of the device.
- High voltage gain: Even with the low input voltage, you can be sure that the operational amplifier will deliver when it comes to the output voltage. It can be as high as 10,000 times more than that out of the input voltage.
- High levels of accuracy: Operational amplifiers are known for their high levels of preciseness. They guarantee accuracy and stability in whichever areas of applications in which they are used. The operation of the om-amps eliminates the noise levels and minimizes drift levels hence guaranteeing accuracy.
What are the limitations of the operation amplifiers?
Most of the limitations that are associated with operational amplifiers are based on the fact that they are analog circuits. This means that they are incapable of handling and processing logic signals Technically, they are not suitable for all digital or logical applications.
Additionally, circuit designers must have a full understanding of all the technical parameters that we have discussed before they consider integrating the operational amplifiers into their application areas.
Choosing an operational amplifier for your application
Now that you know the basics of operational amplifiers, you can proceed to buy one and use it in your application. When choosing operational amplifiers, start by looking at their power specifications voltage, and current capacities of the op-amps. They will determine the suitability of the operational amplifier in your circuit.
Some applications have high power consumption while others have low. Keep this in mind when choosing your operational amplifier. If your application requires high levels of accuracy, then you should pay attention to the input offset voltage of the operational amplifier.
Finally, where you buy operational amplifiers in China matters. Ensure that you buy from reputable suppliers and distributors .
If you want to find more Electronic Components Distributors, please check out the following articles:
Electronic Components Distributors In the USA
Electronic Components Distributors In UK
Electronic Components Distributors In China
Electronic Components Distributors In India
Electronic Components Distributors In Singapore
Electronic Components Distributors In Malaysia
Electronic Components Distributors In Vietnam
Electronic Components Distributors In South Korea
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