Circuit with moderation variable wave shape to eliminate start and close popping noise

Abstract

The invention relates to a circuit for eliminating the popping when switching on or switching off by the use of waveshape with easement change, comprising a switch,a feedback network, an operational amplifier and an output network. When switching on, the first input end of the switch is connected with a low potential, the output end of the output network provides a moderately raised working d. c.bias; when switching off, the first input end of the switch is connected with a reference potential,the output end of the output network provides a moderately degressive working d. c. bias; thereforeeliminating the popping or small noise when switching on or switching off, increasing the reaction speed of the system and saving the cost.

Description

technical field [0001] The invention relates to a circuit for eliminating popping noise during startup and shutdown, especially a circuit for eliminating popping noise during startup and shutdown with a gently changing waveform. Background technique [0002] With the rapid advancement of electronic technology, the application of multimedia is becoming more and more complex. In addition to the need to improve the image quality, the requirements for the quality of the audio signal are becoming increasingly stringent. figure 1 It is a schematic diagram of an audio signal. As shown in the figure, due to sampling, the voltage of the audio signal has positive voltage and negative voltage. However, the working voltage of general integrated circuits is 0~V DD Volts, so first bias the sound signal to V DD / 2 places. [0003] In the prior art, when biasing the sound signal, a direct current bias (DC bias) V DD / 2 is added to this sound signal, however this method will cause a "Bo"...

AI Technical Summary

Problems solved by technology

However, the DC operating voltage still has discontinuity at B and C, and there will also be popping sounds

At the same time, the digital-to-analog converter is adjusting the DC operating voltage from 0 volts to V DD In the process of / 2 volts, the DC operating voltage does not increase linearly, but increases in steps, which will produce many subtle noises

Due to the use of digital-to-analog converters, the response speed of the entire system is often limited by the digital-to-analog converters, and cannot be turned on or off quickly

In order to be able to start up or shut down quickly, it is necessary to use a digital-to-analog converter with a fast response, but this will greatly increase the system cost

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