Signal compressor for audio apparatus

A signal compressor for an audio apparatus having a volume control that is inserted in an audio signal path and is adjustable via a digital setting signal delivered by a digital controller, the compressor comprising:

• a signal processing circuit for receiving an audio signal from the audio signal path, the signal processing circuit configured to process the audio signal to form a tracking signal having characteristics conforming to the intensity of the audio signal;
• a comparator coupled to the signal processing circuit and configured to receive a reference value signal and the tracking signal and to generate a comparison result;
• a counter coupled to the comparator and configured to increase and decrease a count in response to the comparison result;
• a D/A converter coupled to the counter and configured to generate the reference value signal from only the contents of the counter;
• and
• an adder coupled to the counter and configured to link the contents of the counter with the digital setting signal before the digital setting signal is fed to the volume control.

A method for volume control of an audio signal, comprising:

• generating a tracking signal from the audio signal, the tracking signal having characteristics dependent on the volume intensity characteristics of the audio signal;
• generating a comparison signal from a comparison of the tracking signal and a reference signal;
• generating a counter signal responsive to the comparison signal and generating the reference signal from only the counter signal;
• and
• linking the counter signal to a digital setting signal to form a modified digital setting signal used to control a volume control device.

A signal compressor circuit, comprising:

• an audio signal processing circuit having an input terminal coupled to an audio signal source and configured to generate a tracking signal that is responsive to the volume intensity of the audio signal;
• a comparator configured to compare the tracking signal to a reference signal and to generate a comparison signal;
• a counter circuit coupled to the audio signal processing circuit and configured to increase and decrease a counter in response to the comparison signal;
• a D/A converter coupled to the counter circuit and configured to generate the reference signal from only the contents of the counter circuit;
• and
• a linking circuit for linking a digital volume setting signal with the counter to modify the digital volume setting signal.

A circuit for preventing amplitude clipping of a useful signal, the amplitude of which enters into the range of the positive or negative voltage value of a voltage supply source, the circuit comprising:

• a signal compressor configured to receive the useful signal, the compressor comprising:
• a signal processing circuit having an input terminal coupled to a signal source of the useful signal and configured to generate a tracking signal that is responsive to the voltage level of the useful signal;
• a comparator configured to compare the tracking signal to a reference signal and to generate a comparison signal;
• a counter circuit coupled to the signal processing circuit and configured to increase and decrease a counter in response to the comparison signal;
• a linking circuit for linking a signal setting signal with the counter to adjust the voltage level of the useful signal;
• and
• a D/A converter coupled to the counter circuit and configured to generate the reference signal using only the contents of the counter circuit;
• the circuit further comprising a device having an input coupled to a branched-off portion of the useful signal that has not been passed through the signal compressor, the device configured to generate a harmonic distortion signal that is received by the signal compressor and used to control the degree of voltage level adjustment of the useful signal.