Audio apparatus having dynamic ground break resistance
First Claim
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1. An audio apparatus comprising:
- an audio source;
a connector having a signal out pin and a return pin to be coupled to an external load;
a variable resistor circuit coupled to provide variable resistance between the return pin of the connector and a ground plane of the apparatus;
an audio amplifier having a first input coupled to the audio source, a second input coupled to the return pin of the connector, and an output that is coupled to the signal out pin of the connector;
an amplifier headroom detector to detect a measure of headroom of the audio amplifier, wherein headroom is a difference or ratio between (i) peak output voltage of the amplifier and (ii) a power supply voltage of the amplifier; and
a controller having an input coupled to an output of the headroom detector, the controller being to coupled to control the variable resistor circuit in response to the detected measure of headroom.
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Abstract
A method for audio signal processing, where an audio amplifier drives a load through a connector, using 1) an input audio signal, and 2) a signal from a return pin of the connector. Output headroom of the audio amplifier is automatically detected, while the amplifier is driving the load. A variable resistor circuit that is coupled to provide variable resistance between the return pin of the connector and a ground plane, is automatically adjusted, in response to the detected output headroom of the amplifier. Other embodiments are also described and claimed.
23 Citations
20 Claims
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1. An audio apparatus comprising:
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an audio source; a connector having a signal out pin and a return pin to be coupled to an external load; a variable resistor circuit coupled to provide variable resistance between the return pin of the connector and a ground plane of the apparatus; an audio amplifier having a first input coupled to the audio source, a second input coupled to the return pin of the connector, and an output that is coupled to the signal out pin of the connector; an amplifier headroom detector to detect a measure of headroom of the audio amplifier, wherein headroom is a difference or ratio between (i) peak output voltage of the amplifier and (ii) a power supply voltage of the amplifier; and a controller having an input coupled to an output of the headroom detector, the controller being to coupled to control the variable resistor circuit in response to the detected measure of headroom. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for audio signal processing, comprising:
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driving, by an audio amplifier, a load through a connector, using
1) an input audio signal, and
2) a signal from a return pin of a connector to which the amplifier is coupled for driving the load;detecting a measure of output headroom of the audio amplifier while the amplifier is driving the load, wherein headroom is a difference or ratio between (i) peak output voltage of the amplifier and (ii) a power supply voltage of the amplifier; and automatically adjusting a variable resistor circuit that is coupled to provide variable resistance between the return pin of the connector and a ground plane, in response to the detected measure of output headroom of the amplifier. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An audio apparatus comprising:
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an audio source; a connector having a signal out pin and a return pin; a variable resistor circuit having a first node and a second node between which it provides variable resistance, the first node being directly coupled to the return pin of the connector and the second node being directly coupled to a ground plane of the apparatus; an audio amplifier having a first input to receive an audio signal, a second input directly coupled to the return pin of the connector, and an output that is coupled to the signal out pin of the connector; a detector to compare voltage of the output of the audio amplifier with voltage of the first node of the variable resistor circuit; a controller coupled to control the variable resistor circuit in response to the detector'"'"'s comparison; and a ground current detector coupled to detect ground current through the variable resistor circuit, wherein the controller is to signal the variable resistor circuit to change said variable resistance when the detected ground current crosses a zero threshold. - View Dependent Claims (18, 19, 20)
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Specification