Theamplifierusually consists of severalcascaded stages.Amplifierare classified in various ways according to their frequency range, method of operation, end use, type of loading, method of coupling between stages, etc.
Linear amplifier
Linear amplifiers are classified according to how they work. Different amplifier descriptions are based on the following factors:
Based on your input
(a) Small signal amplifier
(b) Large signal amplifier
Based on its frequency response
(a) Audio frequency amplifier (20 Hz to 20 kHz)
b) intermediate frequency amplifier,
(c) Audio frequency amplifier (20 kHz to hundreds of megahertz)
(d) Ultra-high frequency amplifiers (hundreds of thousands of megahertz).
Based on your bias conditions
The classification of amplifiers is:
(a) Class A Amplifier
(b) Class AB amplifier
(c) Class B Amplifiers
(d) Class C Amplifiers
Based on transistor configuration
(a) Common base amplifier
(b) Emitter amplifier
(c) Collector amplifier
Power amplifier
Large signal amplifiers (power amplifiers) are classified according to the location of the rest point. Transistorized power amplifiers handle large signals. Power amplifier are also classified based on the polarization state of the transistor and the amplitude of the input signal. It also gives an idea of which part of the input cycle the transistor conducts.
Power amplifier ratings
Based on this, power amplifiers are classified as
1. Class A power amplifier
2. Class B power amplifier
3. Class AB power amplifier
4. Class C power amplifier
Class A power amplifier
Class A power amplifiers are amplifiers in which the operating point and input signal are such that collector current flows in the output circuit during the complete cycle, i.e. 360 Ó . A Class A amplifier operates on a linear portion of the characteristic. That is, point Q is located approximately in the middle of the linear section of the characteristic curve.
Class B power amplifier
A Class B power amplifier is an amplifier whose operating point is at the extreme (cutoff) of its characteristic curve. The output current only flows for half a cycle, i.e. 180Ω of the input signal. For the other half wave the current is zero. Due to low energy loss, efficiency is high.
Class AB power amplifier
A Class AB amplifier selects the operating point so that the output current flows for more than half the cycle and less than the full cycle of the input signal.
Class C power amplifier
A Class C power amplifier selects the operating point so that the output current flows at less than half the input signal. Current flows in the form of pulses. The efficiency is very high.
In Class A, Class AB, and Class B operating modes, untuned amplifiers are used to tune audio frequencies during Class C High Frequency Amplifier operations.
Another classification of amplifiers
Class D amplifier
Class D amplifier is basically a non-linear switching amplifier It is also called PWM Amplifier In theory, a Class D amplifier can achieve 100% efficiency because there is no period during a cycle where the voltage and current waveforms overlap because current only flows through the transistor when it is turned on.
Class F amplifier
Class F amplifiers can increase efficiency and performance by using harmonic resonators in the output network to achieve square waveform at the output. This class of amplifier achieves high efficiency (more than 90%) when infinite harmonic tuning is used.
Class G amplifier
It offers the improved design of the basic Class AB amplifier design. Class G uses multiple power rails with different voltages and automatically switches between these power rails when the input signal changes. This continuous switching reduces normal power consumption. This results in energy losses due to waste heat.
Class I amplifier
The Class I amplifier has two sets of paired output switching devices integrated in an equivalent push-pull arrangement, where both sets of switching devices sample the identical input waveform.
Class S amplifier
The operation of a Class S amplifier is similar to that of a Class D amplifier. It converts the analog input signal into a square waveform using a delta sigma Modulator. It boosts to increase the output power before finally being used by a Bandpass Filter . The digital signals from this switching amplifier are constantly either fully “ON” or “OFF”.
Class T amplifier
Class T amplifiers are a different type of digital switching amplifier . Nowadays, Class T amplifiers are becoming more and more popular as audio amplifier designs due to the existence of digital signal processing chips and multi-channel surround sound amplifiers. It converts analog signals into digital pulse width modulated (PWM) signals for amplification and increases amplifier efficiency. The design of Class T amplifiers combines the low-distortion signal levels of a Class AB amplifier with the energy efficiency of a Class D amplifier.
Amplifier class according to cable angle
Amplifier Class
Description
Bond angle
Class A
Full cycle 360 O management
θ = 2π
Class B
Half cycle 180 O management
θ = π
Class AB
Just over 180 Oh the management
π <θ <2π
Class C
Just under 180 Oh the management
θ < π
Class D to T
Non-linear ON-OFF switching
θ = 0
Conclusion
In summary, the classification of amplifiers provides an important basis for understanding the complex world of electronic signal amplification. From the basic operation of Class A amplifiers to the efficiency of Class D amplifiers, each category offers different benefits and tradeoffs. By understanding the nuances and applications of these amplifier classes, engineers, hobbyists, and audio enthusiasts can make informed decisions that meet their specific needs. Whether for high-fidelity audio reproduction or industrial power systems, an in-depth understanding of amplifier ratings ensures optimal performance, efficiency and reliability across a wide range of electronic applications.
