- by Kevin Deal
An amplifier is an integral part in building circuits and is important in designing electronic devices. The amplifier itself is an electronic device used to improve the signal, thus increasing the amplitude of the signal. The concept of how the amplifier works can be complex as it involves a lot of conditions and parameters. In fact, amplification is not perfectly efficient because there are always noise, distortion and losses to deal with. The good thing is that there are different types of amplifiers created suitable for different situations.
Basic Types of Amplifiers
- Voltage Amplifier – This type of amplifier is designed to amplify a given voltage to yield larger voltage output. It involves low output impedance and high input impedance.
- Current Amplifier – This amplifier increases the given input current. It is the opposite of voltage amplifier in which it is characterized by high output impedance and low input impedance.
- Transresistance Amplifier – It changes the output voltage conferring to the changing input current. This type of amplifier is also called as current-to-voltage converter.
- Transconductance Amplifier – It changes the output current according to the changing input voltage.
Aside from those basic types of amplifiers, there are other types categorized according to the characteristics, application and operation. In terms of characteristics, amplifiers are categorized according to power output and efficiency, signal gain and linearity. Amplifiers used in different applications include the following:
- Transistor amplifiers – These are commonly used by engineering students. It is a high output multi configuration amplifier that serves as the working base. Transistor amplifiers include metal oxide semiconductor field-effect transistors and bipolar junction transistors.
- Instrument amplifiers – These amplifiers are designed to intensify the sound, music or voice. It is mainly utilized in musical instruments.
Classes of Amplifiers
The power amplifier can handle larger impedance as it is used to drive the loudspeaker load. The different amplifier types can be differentiated through amplifier classes that represents the output signal. Audio amplifiers are the commonly manufactured among the other classes including the class A, B, C and AB. To understand more about amplifiers, it makes sense knowing the details related to the different classes of amplifiers.
- Class A Power amplifier – This amplifier is commonly used because of its simple design. It is also the best among other classes of amplifier as it manifests low level of signal distortion thus provides the best sound. The downside of Class A amplifiers is the low efficiency as they easily heat up caused by continuous power loss. Thus, it is not recommended for high power amplifications.
- Class B Power amplifier – This was designed to solve the issues about heating and efficiency. It is consisting of negative and positive transistor and has higher efficiency. Class B amplifiers are reliable and stable, but lesser heat output.
- Class AB Power amplifier – It is a combination of Class A and B power amplifiers and uses two transistors working together. It also combines the characteristics of Class A and B and commonly used as audio amplifier. Each transistor conducts fairly efficient and there’s no crossover distortion.
- Class C Power amplifier – It’s the most efficient power amplifier, but the linearity and operating cycle is low. This type of amplifier is not recommended as audio amplifiers because of high output distortion. Instead, it is used in specific radio frequency applications in which high efficiency is required. It has two operating modes such as tuned and untuned.
- Class D Power amplifier – It is responsible in converting analog signal to digital signal through pulse density modulation or pulse width modulation. It produces high gain and efficiency and less distortion. It has low power consumption and dissipation, but generates accurate and precise output.
Characteristics of Amplifiers
Amplifiers have different characteristics such as:
- Bandwidth – It is the frequency range that determines the operation of the amplifier.
- Noise – Pertains to the unnecessary extra information in the output.
- Gain – It is the ratio of magnitudes between the output and input signals.
- Skew rate – The extreme rate of the output change.
- Linearity – The proportionality degree between the output and input signals.
- Stability – The capacity to offer reliable and constant output.
- Efficiency – the ratio between the power consumed and output power.
- Output dynamic range – Pertains to the ratio between the smallest and largest output level
Amplifiers are integral part in developing devices particularly those involved in sounds and musical applications. It is important to know the different types of amplifiers in order to choose the right one appropriate to the project.