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Types of audio power amplifier with class d amplifier works

Time：2015-06-02 08:13:14 Source：Network Author：Unknown Clicks：11512

BTL format differs from the form of push-pull, each amplifier's signal BTL is a full signal, RP are just two of the amplifier's output signal. BTL can make full use of the system voltage, BTL format used in low-voltage power supply or battery-powered systems.

One, the kind of ordinary audio amplifiers
According to the different signal conduction angle of ordinary audio amplifiers can be divided into a, b, c and AB classes altogether four categories, all kinds of specific features, such as:
1.A class a amplifier
Class a amplifier input of the transistor characteristic curve is shown in Figure 2, its static operating point for the Q-point. Entered sine audio signal, dang its range not beyond characteristics curve of linear range Shi, set electrode work State in as district and saturation point Zhijian, set electrode current for full of full week guide pass of sine wave, at Guide pass angle for 180 ° (Guide pass angle is to minimum value to maximum value Zhijian accounted for full week of part to calculation, full week guide pass Shi for 180 °), this zoom State distortion degrees smaller. When there is no AC signal input, about half the amplifier (Q) DC current flows through, the least efficient, less than 50%.

Class a power amplifier is mainly used for low-power radio, hearing aids, there are some high power amplifier using this way.
Class 2.B amplifier
Class b amplifier the transistor input characteristic curve is shown in Figure 3, the quiescent point for the Q-point, located on the cut-off point. Power signal and a half weeks conducting (conduction angle is 90 °), the collector output half sine wave. In order to reduce distortion, class b amplifiers are made with double push-pull, each power tube only a week and a half of work, so as to form a complete sine wave.

Class b State the biggest advantage is that when there is no signal in theory there is no DC current flowing through the transistor, namely No DC power consumption efficiency more than 50%. Start because of transistor characteristic curve is nonlinear, in order to reduce distortions, often in two push-pull amplifier transistor base with forward bias voltage, as shown in Figure 4, each power conduction angle is greater than half of the week, the efficiency of 60%~70%, between the working conditions of class a, b, so it is also called a class AB amplifier.

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