As a hardware engineer, especially for engineers applied to audio amplifier, for Class C, Class B, AB, C, C, H, T class, should be particularly familiar. Most engineers may only know part of them, or know about it, in order to make more engineers master more detailed audio amplifier knowledge, the above-mentioned audio power is described in detail.
Amplifier, as the name suggestions, the abbreviation of power amplification. For the voltage or current amplification, the power amplifier requires a certain amount of power, generally working in a large signal state, so the power amplifier circuit generally includes a special problem that voltage amplification or current amplifier circuit, specifically appeared in: 1 output Power is as large as possible; 2 is usually working in large signal states; 3 nonlinear distortion is outstanding; 4 improve efficiency is an important focus; 5 power devices security issues. For the audio amplifier circuit, you also need to pay attention to the above problems.
Different according to the conductivity mode of the amplified circuit, the audio power amplifier circuit is classified according to the two types of simulation and numbers. The analog audio power is usually category A, Class B, AB, G, H TD amplifier, digital circuit power amplifier divided into class D , T class. The following is a detailed introduction and analysis of the above power amplifier circuits.
01
Class A power amplifier (also known as the Amplitude)
Class A is shown in the figure above, and a class of amplifiers (i.e., stop output) will appear in the entire cycle of the signal. However, high heat is generated when the A class amplifier is working, and the efficiency is very low. Although the A class has the above drawbacks, the intrinsic advantage is that there is no cross-failure, and there is some innate advantages in the internal principle. It is ideal for replaying music. It provides very smooth sound quality, tone round and warm, high frequency Transparent opening, the advantages of intensive intensity. Single-ended amplifiers are Working methods, the push-pull amplifier can be a class A or a class B or a class.
02
Class B power amplifier (also known as B "amplifier)
Class B power generation means that the positive and negative two and semi-three weeks of the sinusoidal signal are widely enlarged by the two transistors of the push-pull output stage. Each transistor's conductivity time is half a cycle of the signal, which usually produces us. Cross the cross. The distortion of the distortion can even disappear with the adjustment of the analog circuit. The efficiency of the Class B amplifier is significantly higher than that of Class A.
03
AB class power (also known as A-class)
The AB class power is bound to between the AB and the Class B, and each transistor conduction time of push-pull enlargement is greater than one cycle of the signal is less than one cycle. Therefore, the AB class power is effective to solve the cross distortion problem of the cross-amplifier, and the efficiency is high than the A amplifier, so it has obtained an extremely wide application.
04
Class D power (also known as Ding class amplifier)
Class D power is also known as digital amplifier, using extreme high frequency conversion switch circuits to enlarge audio signals, the specific working principle is as follows: D-class power amplifier, the high-frequency carrier signal is still maintained when the audio signal cycle changes Not changed, therefore, when the audio frequency is relatively low, the number of carriers of the PWM is still high, so the frequency of the frequency carrier and reduction of distortion is very advantageous, and the carrier frequency strip principle audio signal frequency is not present, and therefore does not exist. Mutual interference problem between wave. Many di amplifiers up to 1000W, the volume is only as large as the VHS tape. Such amplifiers are not suitable for amplifiers used as wideband, but there are more applications in active ultra-low soundboxes.
05
G class power
G class power is an improved form of a multi-power AB class power amplifier. G class power makes full use of this favorable conditions with extreme peak factors (10-20 dB). Most of the time, the audio signal is at a lower amplitude, and the minimum time will show higher peaks. The following figure is a typical functional block diagram of the G class generating IC.
The G class amplifier uses an adaptive power rail and utilizes a built-in buck converter to generate a headphone amplifier positive supply voltage. The charging pump is inverted to the amplifier positive supply voltage and generate an amplifier negative power supply voltage. This makes the headphone amplifier output can be concentrated in 0V. When the audio signal is low, the buck converter generates a low amplifier negative power supply voltage. This will make low noise, high-fidelity audio, and minimize the power consumption of the G class amplifier, compared to the traditional AB-based headphone amplifier, Glass G-class amplifiers have higher efficiency. The amplification principle of this type of amplifier is the same as the AB class power amplifier. An important feature is that the power supply portion is used in two or more sets of voltage, low power operations, high-power automatic switching to high voltage.
06
H class power
The amplifying circuit portion of this type of amplifier is the same as the principle of the AB class, but the power supply portion uses a switching power supply that adjusts the multi-stage output voltage, automatically detects the selection of the output power for the power supply voltage.
07
K class power
K class power is integrated into internal boosting boost circuits and various amplifier circuits. Everyone knows that the D-class power is just a higher efficiency in many power discharges, and K class power is just integrated internal integration as needed. Subweaking boost circuit and the required power amplifier circuit, if the demand efficiency is high, plus D class power, and the sound quality will be added to add AB class power.
08
T class power
The principle of this type of amplifier is the same as the principle of Class D power, but the signal portion uses DDP technology (core is a small signal adaptation algorithm and prediction algorithm). The working principle is as follows: The current of the audio signal enters the speaker through the DDP. After performing operational processing, control the high-power high-frequency transistor on or off, thereby achieving the high-fidelity linearity of the audio signal. This type of amplifier has a high efficiency, small distortion, and sound quality can be comparable to the AB class work.
The above figure shows the internal module construct of TA2020, which can be seen from the above figure, the interior of the chip mainly focused on processing and modulation modules, thereby achieving high quality audio.
09
TD class power
The magnitude of the audio amplifier is the same as the principle of the AB class, but the power supply portion adopts a fully independent high-precision adjustable digital power supply, the voltage process value is 0.1V, the automatic detection power to adjust the voltage. High or decrease. This type of amplifier requires a high-precision adjustable digital power supply, which requires a special design for the power supply, and cannot be concentrated on one chip, so power amplifier is mainly used on the advanced audio, while the circuit is complicated. For later 6,7,9 class power plants require special power supplies, the function is not concentrated on a piece of IC. For classic A, Class B, AB, and Class D. There are special ICs. In actual design, various types of power amplifier circuits are applied to different fields, only need to be based on this, plus corresponding power or processing modules.
Editor in charge: LQ, Read full article, original title: Hardware engineer must know the audio power amplifier circuit Daquan
Article Source: [Micro Signal: MCU168, WeChat public number: Hardware siege] Welcome to add attention! Please indicate the source of the article.
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