Sunday, January 16, 2011
Weak current College】 【】 amplifier category.
First, A class (class a) amplifier
A class (class a) amplifier, a current flows through the continuous and all output devices of an amplifier. This amplifier, to avoid the device switch of nonlinear, so long as bias and dynamic range control properly, just from the distortion of perspective, to think that it is a good linear amplifier. A class amplifier in structure, there are two different ways of working. One of the two efdtl associated work, their bias current to increase to normal load have enough current to flow without making any devices cut-off. This measures the biggest advantage is that it won't suddenly run out of output current, if load impedance lower than the rated value, amplifier will appear as short term, on the distortion may be slightly increased, but will not appear on the serious shortcomings in Xenia. Another class can be called as a control current source type (VCIS), it is essentially a separate efdtl, with an active emitter load in order to achieve the appropriate current relief. This class acts as the output level, you need before you start the design of the desired driver impedance is much less clear.
II. category b (r) amplifier
Class b (r) amplifier, refers to devices breakover time is 50 per cent of a job category. This type of amplifier can be said to be one of the most popular, perhaps the amplifier amplifier has a 99 percent belong to this category. Because we are more familiar with the details here.
Third, AB class amplifier of CPI) [
AB class amplifier (a b), is actually A class (class a) and b (r), the combination of each device's breakover time in between 50-100%, depending on the size of the bias current and output level. Class amplifier bias press B class (b) design, and increase the bias current, make amplification into AB class (a class).
AB class amplifier (a b) in the output is below a certain level, the two output devices are conduction and the status of work in A class (class a); when the level elevated, the two devices will be completely closed and the other devices will supply more current. This AB class (a b) status begins, the distortion would suddenly rise, its linear invisibility A class (class a) or b (r). But in my view, the proper use of it is that it's A class (class a), and when the time for low load impedance may continue to better work.
4. a category c (r) amplifier
C-class (r) amplifier, refers to devices breakover time is less than 50 per cent of the working class. This type of amplifier, generally used for RF amplifier, it is difficult to find examples of use for audio amplification.
Five class-d amplifier (Group d)
This type of amplifier, characterized by intermittent and converters for opening, the frequencies more than audio, you can control the signal duty cycle so that its average value represents the instantaneous-level audio signal, this condition is known as pulse-width modulation (PWM), its efficiency in theory, is very high.
However, real difficulties or very large, because of the high power 200kHz square wave is not a good starting point is not clear from the distortion of perspective, in order to guarantee the effectiveness of the sampling frequency must be a steep cutoff frequency of the low-pass filter into the amplifier and the speakers, to eliminate the vast majority of RF components, this requires at least four inductance (consider stereo), low-cost nature does. In addition, in the frequency response, it can only be used for a particular load impedance guaranteed flat frequency response.
6. E-class (r) amplifier
This type of amplifier is an extremely clever application of semiconductor technology, which in almost all working hours, through the voltage or current is small, i.e. low power dissipation. Unfortunately, it is used only for RF technology, but not for audio.
7. F class (f) amplifier
This type of amplifier, as far as is known and nonexistent seems to need additional vacancies.
8 G type (g type) amplifier
This type of amplifier, appear to be class b (r) or AB (a b) amplifier some similar. For small output signal, its supply current from low voltage source; for the ' big signal ', power supply will be converted to a high voltage source. In this way, than class b (r) is more efficient. However, this improvement does not seem to be beyond the multiple output devices cost as well as switching diode in high frequency when converting neat technical difficulties to which their use is not suitable for some high power of professional equipment. In addition, G type (g type) amplifier distortion arising from, probably higher than the corresponding b-class (r), but also has information on conversion details carefully designed, will make the difference between smaller.
9 h [Xin class) amplifier
This type of amplifier, also appear to be class b (r), its characteristics is dynamically enhance the single power supply voltage (converting to another voltage source) to improve the efficiency of the circuit structure is bootstrapping.
10, S class amplifier
S class amplifier by sandeman, named an amplifier. This type of amplifier, the use of a class a (class a) amplifier, their current capacity is very limited, and B class (r) amplifier for back-up, on the connection so that the load is rendered as a higher resistance. Tech-nicsSE-1000 approach and this is very similar.