A method for eliminating the pop sound when the audio power amplifier is turned on

Abstract

The invention relates to an audio power amplifier output technology, and discloses a method for eliminating power-on POP sound of an audio power amplifier. In a working process of an earphone or a horn, the output common-mode voltage is Vref, the output end voltage is 0V before power-on, so that if the power-on speed is too fast, the POP sound may be heard at the output end. A traditional method is to control the reference common-mode voltage to be slowly powered on, and thus the output end of the power amplifier can be slowly powered on. However, the traditional method needs a DAC to generatea slow power-on waveform, the chip area is increased, and meanwhile, the DAC output needs to be filtered, and a filtering PIN and a capacitor are required. According to the method disclosed by the invention, the common-mode voltage Vref can be reached by slowly charging the output end of a chip power amplifier, and meanwhile, the slow power-on waveform is generated through an audio DAC, an independent DAC is not required, and thus the chip area can be saved, and the filtering PIN and the capacitor can also be saved. And meanwhile, as the output end and the input end of the power amplifier arecut off in a power-on process, the power amplifier can be directly powered on, and the reference voltage adopts Vref. Although a pulse exists at the input end of the power amplifier, the pulse cannotbe transferred to the output end, and the POP sound cannot be generated.

Description

technical field [0001] The invention relates to the technical field of audio output of consumer electronics, in particular to optimizing the power-on process of the power amplifier to eliminate the POP sound when the power amplifier is powered on, thereby improving user experience. Background technique [0002] As the last stage output of consumer electronic products, audio power amplifier, such as headphones or speakers, often ultimately affects the audio experience of the product. At the same time, due to the extremely high sensitivity of the human ear, very small audio fluctuations will be perceived by the human ear, so the output of the audio power amplifier must meet the user's auditory experience, and it must be slow and smooth during various switching and switching processes, so that Make sure that no POP sound is produced at the audio output. [0003] figure 1 It is a basic audio power amplifier output circuit. For consumer products, VSS is actually connected to GN...

AI Technical Summary

Problems solved by technology

However, this method must increase a digital-to-analog converter 2, which increases the chip area

At the same time, due to the high sensitivity of the human ear, there are also requirements for the accuracy of the digital-to-analog converter 2. At the same time, in order to ensure that the output of the digital-to-analog converter 2 does not appear steps, a filter capacitor is required at the common-mode voltage reference of the power amplifier. Generally, in order to save the on-chip capacitor area, the filter capacitor is placed outside the chip, which requires consumption of a PIN pin resource

overall higher cost

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