Audio amplification device and method, and terminal

Abstract

The invention provides an audio amplification device and method, and a terminal. The device comprises an application processor which is used for adjusting volume and controlling an output voltage of a direct current power supply; the direct current power supply which is used for driving an audio amplifier; a digital to analog converter which is used for outputting an audio signal to the audio amplifier; and the audio amplifier which is used for amplifying and outputting the audio signal received from the digital to analog converter. The direct current power supply supports bus voltage regulation. According to the device, the method and the terminal, the output sound quality is not influenced by the voltage regulation process of the audio amplifier PA.

Description

technical field [0001] Embodiments of the present invention relate to an audio amplifier voltage regulation method, and in particular to an audio amplifier device, method and terminal. Background technique [0002] In the existing field of mobile terminals, there are many solutions for low-power audio, among which the relatively new one is the "ClassH" solution, such as figure 1 As shown, by checking the output voltage of the digital-to-analog converter (DAC), adjusting the positive and negative power supply voltages, tracking the signal size to make changes in size, and reducing the power supply voltage of the audio amplifier (PA), so as to achieve the purpose of reducing power consumption. But existing schemes have many deficiencies: [0003] 1. The left and right channels share a set of DC power supply DC-DC (if you do not share a set, the cost will double), because the signals of the left and right channels are different, the DC power supply DC-DC can only track the int...

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Problems solved by technology

[0003] 1. The left and right channels share a set of DC power supply DC-DC (if you do not share a set, the cost will double), because the signals of the left and right channels are different, the DC power supply DC-DC can only track the integrated value of the left and right channels, But it is not equal to any channel. The voltage of the part that is different from the left and right channels is noise to the power supply. Therefore, when the ClassH amplifier is working, it injects unwanted noise voltage from the power supply, and finally affects the audio amplifier. (PA) output sound quality;

[0004] 2. There is no way for the output of the DC power supply DC-DC to filter through a large capacitor (it is not good for noise and response). If a large capacitor is added, the DC-DC power supply will not be able to track the change in the size of the signal.

When the signal swings to the positive half cycle, the change of the negative half cycle power supply fluctuates for the supply voltage of the push-pull transistor of the negative rail, because the internal resistance of the push-pull transistor of the negative rail is not infinite, that is to say, the PSSR is not infinite, so the negative The fluctuation on the power supply will flow to the output terminal through the transistor, causing the deterioration of the sound quality;

[0006] 4. When the voltage is reduced to a certain level, the voltage cannot continue to decrease, otherwise it will lead to abnormal operation of the PA, such as the abnormality of the bias circuit, so there is an inflection point between the voltage change and no change, at which the inflection point is introduced A large number of high-order harmonics affect the sound quality;

[0007] 5. Since the DC power supply DC-DC changes with the change of the output voltage, the audio amplifier PA itself has distortion, so the DC power supply DC-DC tracks the output change, and the output distortion of the DC power supply DC-DC will be relatively large, (if If it is not too large, you can directly use the output of the DC power supply DC-DC to block the DC and then output it). According to the current technology, the distortion will be relatively large. These distortions appear as noise on the power supply of the audio amplifier PA, and these noises will also Spilling into the output, eventually affecting the sound quality;

[0008] 6. Since the voltage of the positive and negative power supplies is relatively low near the zero-crossing point of the signal, the bias circuit inside the audio amplifier PA is working in a critical state, and the performance will change, which will lead to the static operating point, frequency response, and rotation of the operational amplifier. Frequency, offset voltage, offset current, distortion characteristics, bandwidth and other characteristics change. Since the zero-crossing point is when the signal is weakest, the influence of this part is superimposed at this time, and the impact on the sound is particularly large.

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