Power amplifier-that is what we often say "power amplifier", its role is to amplify the input signal, we know that the sound signal or the converted electrical signal, its essence is "wave", if it is in the form of a function Shown as a sine wave. Hey ~ Think about the sine function learned in math, don't forget it. Power amplification amplifies the "wave" amplitude. How to amplify the amplitude of "waves"? We know that there is a kind of electronic device called "transistor", which is often called "transistor", and we often say "power tube" in the power amplifier, which has the effect of amplifying the current. We don't need to control it for the principle of amplification ... This preliminary knowledge can talk about the type of power amplifier.
1. Usually according to the different conduction methods of the power amplifier tube in the power amplifier, it can be divided into Class A power amplifier (also known as Class A), Class B power amplifier (also known as Class B), Class A and B power amplifier (also known as Class AB), Class A power amplifier is Refers to a type of amplifier that does not have current cutoff (ie, stops output) in any power output element of the amplifier during the entire period of the signal (both positive and negative half cycles of the sine wave). Class A amplifiers generate high heat during operation and have low efficiency.
2. Class B amplifier refers to the "arm" (two sets of amplification elements) of the push-pull output stage, which is the positive and negative two and a half cycles of the sinusoidal signal. Half cycle. The advantage of Class B amplifier is high efficiency. However, there is a problem of convergence between positive and negative half cycles. There is a threshold voltage for transistor amplification current. Below the threshold voltage, the relationship between voltage and current is not linear, so when the input voltage is low, there is a dead zone in the output voltage, which is reflected in the power amplifier, that is, the junction of the positive and negative half cycles. The later signal lost its similarity to the original signal. That is, there is "distortion" in this low voltage, which is called "crossover distortion". In turn, we know that there is no such distortion in Class A amplifiers. !
3. Class A and Class B amplifiers are between Class A and Class B. The on-time of each "arm" of the push-pull amplifier is greater than half a cycle of the signal and less than one cycle. In this way, the low-voltage nonlinear amplification distortion caused by the threshold voltage is avoided, that is, the crossover distortion problem of the Class B amplifier is solved. At the same time, its efficiency is higher than the Class A amplifier. According to the number of power amplifier output stage amplification components, it can be divided into single-ended amplifiers and push-pull amplifiers.
The output stage of the single-ended amplifier is amplified by two a half cycles of the signal by one amplifying element (or multiple elements but connected in parallel). Single-ended amplifiers can only take Class A working conditions.
The output stage of the push-pull amplifier has two "arms" (two sets of amplification elements). When the current of one "arm" increases, the current of the other "arm" decreases, and the state of the two switches in turn. To the load, it seems that an "arm" is pushing and an "arm" is pulling together to complete the current output task. Although class A amplifiers can use push-pull amplification, it is more common to use push-pull amplification to form a class B or class A amplifier. According to the type of power amplifier tube in the power amplifier, it can be divided into a tube amplifier and a stone machine. This is relatively simple. The power amplifier tube of the tube amplifier is an electronic tube, and the power amplifier tube of the stone amplifier is a transistor.
1. Usually according to the different conduction methods of the power amplifier tube in the power amplifier, it can be divided into Class A power amplifier (also known as Class A), Class B power amplifier (also known as Class B), Class A and B power amplifier (also known as Class AB), Class A power amplifier is Refers to a type of amplifier that does not have current cutoff (ie, stops output) in any power output element of the amplifier during the entire period of the signal (both positive and negative half cycles of the sine wave). Class A amplifiers generate high heat during operation and have low efficiency.
2. Class B amplifier refers to the "arm" (two sets of amplification elements) of the push-pull output stage, which is the positive and negative two and a half cycles of the sinusoidal signal. Half cycle. The advantage of Class B amplifier is high efficiency. However, there is a problem of convergence between positive and negative half cycles. There is a threshold voltage for transistor amplification current. Below the threshold voltage, the relationship between voltage and current is not linear, so when the input voltage is low, there is a dead zone in the output voltage, which is reflected in the power amplifier, that is, the junction of the positive and negative half cycles. The later signal lost its similarity to the original signal. That is, there is "distortion" in this low voltage, which is called "crossover distortion". In turn, we know that there is no such distortion in Class A amplifiers. !
3. Class A and Class B amplifiers are between Class A and Class B. The on-time of each "arm" of the push-pull amplifier is greater than half a cycle of the signal and less than one cycle. In this way, the low-voltage nonlinear amplification distortion caused by the threshold voltage is avoided, that is, the crossover distortion problem of the Class B amplifier is solved. At the same time, its efficiency is higher than the Class A amplifier. According to the number of power amplifier output stage amplification components, it can be divided into single-ended amplifiers and push-pull amplifiers.
The output stage of the single-ended amplifier is amplified by two a half cycles of the signal by one amplifying element (or multiple elements but connected in parallel). Single-ended amplifiers can only take Class A working conditions.
The output stage of the push-pull amplifier has two "arms" (two sets of amplification elements). When the current of one "arm" increases, the current of the other "arm" decreases, and the state of the two switches in turn. To the load, it seems that an "arm" is pushing and an "arm" is pulling together to complete the current output task. Although class A amplifiers can use push-pull amplification, it is more common to use push-pull amplification to form a class B or class A amplifier. According to the type of power amplifier tube in the power amplifier, it can be divided into a tube amplifier and a stone machine. This is relatively simple. The power amplifier tube of the tube amplifier is an electronic tube, and the power amplifier tube of the stone amplifier is a transistor.
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