Audio output POP (Post Office Protocol) sound eliminating circuit

Abstract

The invention discloses an audio output POP (Post Office Protocol) sound eliminating circuit, which comprises a reference voltage generation module, a voltage follower and an audio amplifier; the reference voltage generation module is connected to the first input end of the voltage follower, and is grounded via a decoupling capacitor C1; the second input end of the voltage follower is connected to the output end of the voltage follower and the forward output end of the audio amplifier; the reverse input end of the audio amplifier is used for inputting audio signals; the output end of the audio amplifier is connected to one end of a direct current blocking capacitor C0; the other end of the direct current blocking capacitor C0 is used for connecting an audio player; the output end of the voltage follower and the output end of the audio amplifier are connected via a first CMOS (Complementary Metal Oxide Semiconductor) switch; and the first input end of the voltage follower and the output end of the audio amplifier are connected via a second CMOS switch. According to the audio output POP sound eliminating circuit disclosed by the invention, all POP sounds generated in power supply and outage process of the audio output as well as in startup and shutdown process of the audio amplifier can be completely eliminated, the auditory feeling is improved, the structure is simple and the cost is low.

Description

technical field [0001] The invention belongs to the field of consumer / applied electronics, and more specifically relates to an audio output POP sound elimination circuit. Background technique [0002] figure 1 It is a schematic diagram of a typical audio output application, wherein the audio power amplifier 10 in the audio chip 11 is connected to an external DC blocking capacitor C 0 Drive the audio player 12 to work. When the audio system works normally, the audio output signal HPOUT of the audio power amplifier 10 has a DC component that is about half of the voltage value of the power supply VDD, and its specific value is determined by the common-mode reference level V R Decide. Due to the blocking capacitor C 0 The presence of the DC component in the audio output signal HPOUT will be filtered out, which not only reduces the power consumption of the system, but also avoids the damage of the DC component to audio playback equipment such as headphones. [0003] When the...

AI Technical Summary

Problems solved by technology

This solution needs to occupy a large layout area, and even requires an external capacitor to generate the control signal of the switch, thus making the design complicated

[0007] To sum up, although the current POP sound elimination methods can suppress POP sound to a certain extent, they either require off-chip devices, occupy a large layout area, or significantly increase the difficulty of product design, and are difficult to be applied and promoted.

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