Mode-switching of audio amplifiers

Abstract

In some embodiments, an audio amplifier can be controlled by a method that includes generating an enable signal based on a masking sound in an audio signal, and controlling a mode transition of the audio amplifier between a current source mode and a voltage source mode based on the enable signal. The mode transition of the audio amplifier can result in an artifact sound, the generating of the enable signal and the controlling of the mode transition can be achieved such that the artifact sound is substantially masked by the masking sound.

1 . A method for controlling an audio amplifier, the method comprising:
 generating an enable signal based on a masking sound in an audio signal; and   controlling a mode transition of the audio amplifier between a current source mode and a voltage source mode based on the enable signal, the mode transition of the audio amplifier resulting in an artifact sound, the generating of the enable signal and the controlling of the mode transition achieved such that the artifact sound is substantially masked by the masking sound.   
     
     
         2 . The method of  claim 1  wherein the masking sound is selected to be spectrally similar to the artifact sound. 
     
     
         3 . The method of  claim 1  further comprising generating the masking sound based on a comparison of a crest factor of the audio signal and a crest factor threshold level. 
     
     
         4 . The method of  claim 3  wherein the crest factor of the audio signal includes a high frequency crest factor. 
     
     
         5 . The method of  claim 4  wherein the generating of the masking sound includes generating an output based on a comparison of the high frequency crest factor and the crest factor threshold level, such that the audio signal passed through a high pass filter and an absolute value circuit provides the high frequency crest factor. 
     
     
         6 . (canceled) 
     
     
         7 . The method of  claim 3  wherein the crest factor of the audio signal is obtained by a combining a peak audio level of the audio signal and an average audio level of the audio signal. 
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 7  wherein the peak audio level and the average audio level are obtained from a common frequency range. 
     
     
         10 . The method of  claim 9  wherein the common frequency range includes a frequency associated with the artifact sound. 
     
     
         11 . (canceled) 
     
     
         12 . The method of  claim 7  wherein the peak audio level is obtained from a first frequency range, and the average audio level is obtained from a second frequency range that is different than the first frequency range. 
     
     
         13 . The method of  claim 12  wherein the first frequency range includes a frequency associated with the artifact sound. 
     
     
         14 . (canceled) 
     
     
         15 . The method of  claim 13  wherein the second frequency range includes a frequency range outside of the first frequency range. 
     
     
         16 . The method of  claim 15  wherein the second frequency range includes a low frequency range. 
     
     
         17 . The method of  claim 12  wherein the peak audio level is obtained by high pass-filtering the audio signal. 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 12  wherein the average audio level is obtained by passing the audio signal through an absolute value circuit. 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . The method of  claim 1  further comprising identifying a target mode for the mode transition among a plurality of modes including the current source mode and the voltage source mode. 
     
     
         23 . The method of  claim 22  wherein the target mode is identified based on an average audio signal level and threshold levels associated with the current source mode and the voltage source mode. 
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . (canceled) 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . The method of  claim 1  further comprising identifying a low audio condition that provides a reduced level of the artifact sound when the mode transition occurs during the low audio condition. 
     
     
         34 . (canceled) 
     
     
         35 . The method of  claim 1  further comprising implementing a change in output resistance of the amplifier in one or more steps. 
     
     
         36 . (canceled) 
     
     
         37 . (canceled) 
     
     
         38 . (canceled) 
     
     
         39 . (canceled) 
     
     
         40 . (canceled) 
     
     
         41 . (canceled) 
     
     
         42 . (canceled) 
     
     
         43 . (canceled) 
     
     
         44 . A method for operating an electronic device, the method comprising:
 operating an amplifier to amplify an audio signal; and   controlling the amplifier, the controlling including generating an enable signal based on a masking sound in the audio signal, the controlling of the amplifier further including controlling a mode transition of the amplifier between a current source mode and a voltage source mode based on the enable signal, the mode transition of the amplifier resulting in an artifact sound, the generating of the enable signal and the controlling of the mode transition achieved such that the artifact sound is substantially masked by the masking sound.   
     
     
         45 . The method of  claim 44  wherein the electronic device is a portable electronic device powered by a battery. 
     
     
         46 . (canceled)