Audio mute circuit

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Audio circuits need a method to "mute" the output so that there is no signal at all when desired. One may need to mute when switching programs, at the push of a button, in response to a control signal, when powering up and down, and when the power cable is disconnected.

Types of mute circuits: 1.) inline analog switch 2.) electromechanical relay 3.) MOSFET pulldown

Audio digital to analog converter (DAC) ICs sometimes have outputs that act as control for external mute circuits. These mute signals go active upon power-up initialization, reset, muting, a certain number of consecutive "0" samples, or if the input clock ratio is incorrect. Also, use of this mute control function can enable the system to achieve idle channel noise and signal-to-noise (SNR) ratios which are only limited by the external mute circuit's characteristics. The mute control output signal polarity is often programmable. It is desirable to mute at the zero crossing of the signal, so that there is no high slew rate signal to zero which comes out like a pop. Multichannel DACs can have programmable grouping of outputs. The ramp rate up to full signal can be also programmable.