In the above image, an Ideal Class B amplifier configuration has been shown. Two devices provide combined current drive for the load. It is created using two active devices which conduct half of the actual cycle, ie 180 degrees of the cycle. The Class B amplifier is a bit different from the Class A. The efficiency can be improved using inductively coupled configuration but the efficiency in such case is not more than 45-50%, thus it is only suitable for low signal or low power level amplification purposes. The efficiency is very poor in Class A amplifiers, theoretically, the efficiency varies between 25 to 30 % if used with the usual configuration. The power supply and the bias construction need careful component selection to avoid unwanted noise and to minimize the distortion.īecause of high power loss in Class A amplifier, it emits heat and requires higher heat sink space. Also, due to high linearity, Class A amplifier provides distortion and noises. Due to continuous conducting nature, the class A amplifier introduce high power loss.
Other than these advantages, Class A amplifier is easy to construct with a single-device component and minimum parts count.ĭespite the advantages and high linearity, certainly, it has many limitations. Due to this never turn off feature, Class A amplifier provides better high frequency and feedback loop stability. The bias of the transistor remains ON all of the time. In the below image an ideal class A amplifier is shown.Īs we can see in the image, there is one active element, a transistor. As we stated above, a 360-degree conduction angle means the amplifier device remains active for the entire time and use complete input signal. In case of Class A amplifier, the conduction angle is 360 degree. These classes are not only used in Power Amplifier but also used in Audio Amplifiers circuits.Ĭlass A amplifier is a high gain amplifier with high linearity. So, if an amplifier provides 360-degree conduction angle, then the amplifier used complete input signal and the active element conducted through the 100% time period of a complete sinusoidal cycle.īelow, we will demonstrate traditional Power amplifier classes ranging from Class A, B, AB and C, and also demonstrate Class D amplifier which is widely used in switching designs. If the amplifier is always ON during a cycle, the conduction angle will be 360 degrees.
#Class d power amplifier full
This conducting angle is highly proportional with the Amplifiers on time during a full cycle. The input cycle is the conduction angle derives from the sinusoidal wave conduction in the amplifier input. Sometimes, improved version of traditional classes are assigned a letter to classify them as a different class of amplifier, like class G amplifier is a modified Amplifier class of Class B or Class AB amplifier.Ĭlasses of the amplifier represent the input cycle proportion when the current is passed through amplifier. Other Classes are modern amplifiers which use switching topologies and PWM (Pulse Width Modulation) technique to drive the output load. Out of those classes most commonly used audio amplifiers classes are A, B, AB, C. There are different classes of amplifiers starting from A, B, C, AB, D, E, F, T etc.
According to their specifications, Amplifiers are assigned different letter or alphabets which represent their classes. Different type of power amplifiers gives different responses when passing current through them. So here we will explore different classes of amplifiers along with their advantages and disadvantages.Ĭlassifications of Amplifiers using LettersĪmplifier classes are the identity of amplifier’s performance and characteristics. But, other than this application-specific purpose, there are huge differences in various types of amplifiers, mainly in Power Amplifiers.
In Audio related electronics pre-amplifier and power amplifiers are two different types of amplifier systems which are used for sound amplification related purposes. In electronics, Amplifier is the most commonly used circuit device with huge application possibilities.
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