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Audio frequency apparatus and silencing apparatus

A technology of noise reduction device and audio frequency, which is applied in the parts of amplifying device, low frequency amplifier, pulse processing, etc., can solve the problems of ignoring collision noise and speaker damage, etc.

Active Publication Date: 2009-12-02
MEDIATEK INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Even though this collision noise will end in a short time, it will cause great damage to the sensitive speakers
The traditional noise reduction circuit can only eliminate the impact noise at the moment of power on, but ignores the impact noise at the moment of power off

Method used

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  • Audio frequency apparatus and silencing apparatus
  • Audio frequency apparatus and silencing apparatus
  • Audio frequency apparatus and silencing apparatus

Examples

Experimental program
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Embodiment Construction

[0046] In order to make the above and other objects, features, and advantages of the present invention more comprehensible, several embodiments are specifically listed below and described in detail with the accompanying drawings.

[0047] figure 1 A block diagram is used to illustrate an implementation of the audio device proposed in this case, which includes an audio chip 10, a noise reduction circuit 12, a power detection circuit 14, and a first capacitor C 1 , and a second capacitor C 2 . The audio chip 10 is coupled to the first and second capacitors C 1 with C 2 . The noise canceling circuit 12 is coupled to the first capacitor C 1 and power detection circuit 14.

[0048] At the moment when the power of the audio device is turned on / off, the voltage of the audio output signal suddenly rises / falls. This voltage increase / decrease action produces a collision noise. figure 1 In the illustrated embodiment, the audio output signal S is passed through the noise reduction...

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PUM

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Abstract

An apparatus and a muting circuit. The apparatus comprises an amplifier, a mute circuit, a pull-down circuit, and a power detection circuit. The amplifier receives a power supply voltage and a common mode voltage, and amplifies an audio input signal to generate an audio output signal. The mute circuit, coupled to the amplifier, conducts the audio output signal to about ground level upon receiving a mute signal. The pull-down circuit, coupled to the amplifier, pulls the common mode voltage to about ground level upon receiving a pull-down signal. The power detection circuit, coupled to the mute circuit and the pull-down circuit, detects power-up or power-down of the power supply voltage, and generates the mute signal and a pull-down signal according to the power-up or power-down operation.

Description

technical field [0001] The invention relates to an audio device, in particular to a noise canceling circuit in the audio device. Background technique [0002] When a traditional audio device receives an unsatisfactory or unnecessary audio input signal, it usually uses a noise canceling circuit to turn off the output of the audio device. Such audio devices usually include an audio amplifier for amplifying an audio input signal to drive a load (such as a speaker) to which the audio device is coupled. With the aforementioned noise canceling circuit active, the associated amplified signal of an undesirable or unnecessary audio input signal will be attenuated. [0003] The power supply of the audio amplifier will produce a collision noise (generated by the sudden rise or fall of the potential in the circuit) when it is turned on or off. Even if this collision noise will end in a short time, it will cause great damage to the sensitive speaker. The traditional noise reduction ci...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03F3/181H03F1/00H03K5/1254H03K17/60
Inventor 蔡仁哲王有伟
Owner MEDIATEK INC