Amplifier clipping distortion indicator with adjustable supply dependence
First Claim
1. An audio amplifier system for generating a clipping distortion detection signal which identifies the occurrence of excessive clipping distortion, said system comprising:
- an audio amplifier having a voltage gain, a first input for receiving an input voltage, and an output for generating an amplified output voltage;
a supply voltage supplied to said audio amplifier, said supply voltage determining a maximum amplifier output voltage;
means for generating a comparison voltage which is indicative of the output voltage divided by the voltage gain;
a clip detector voltage comparator having a first input for receiving the input voltage, a second input for receiving the comparison voltage, a voltage offset and a comparator output for providing a clipping distortion detection signal when the input voltage deviates from the comparison voltage in excess of the offset voltage so as to indicate the detection of excessive clipping distortion; and
compensation means for adjusting the voltage offset as a function of the supply voltage so as to achieve an adjustable maximum percent distortion.
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Accused Products
Abstract
A circuit and method are provided for generating a clipping distortion detector output signal for an integrated circuit audio amplifier which is independent of operating temperature and supply voltage. The system includes an audio amplifier having a voltage gain, a first input for receiving an input voltage and an output for generating an amplified output voltage. A supply voltage is supplied to the audio amplifier and the supply voltage determines the maximum amplified output voltage. A comparison voltage is generated which is indicative of the output voltage divided by the voltage gain. A clip detector voltage comparator receives the input voltage and the comparison voltage and provides a clipping distortion detect signal when the input voltage deviates from the comparison voltage in excess of an offset voltage which is indicative of detection of excessive clipping distortion. According to one embodiment, the offset voltage is adaptively controlled as a function of the supply voltage so as to maintain a substantially constant maximum percent distortion. According to a second embodiment, the offset voltage is adjusted as a function of supply voltage to achieve an adjustable maximum percent distortion. In addition, the offset voltage is also controlled as a function of temperature to provide temperature compensation. The supply voltage and temperature compensation may be achieved by generating a current source as a function of supply voltage and temperature.
73 Citations
11 Claims
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1. An audio amplifier system for generating a clipping distortion detection signal which identifies the occurrence of excessive clipping distortion, said system comprising:
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an audio amplifier having a voltage gain, a first input for receiving an input voltage, and an output for generating an amplified output voltage; a supply voltage supplied to said audio amplifier, said supply voltage determining a maximum amplifier output voltage; means for generating a comparison voltage which is indicative of the output voltage divided by the voltage gain; a clip detector voltage comparator having a first input for receiving the input voltage, a second input for receiving the comparison voltage, a voltage offset and a comparator output for providing a clipping distortion detection signal when the input voltage deviates from the comparison voltage in excess of the offset voltage so as to indicate the detection of excessive clipping distortion; and compensation means for adjusting the voltage offset as a function of the supply voltage so as to achieve an adjustable maximum percent distortion. - View Dependent Claims (2, 3, 4, 5)
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6. An audio amplifier system for generating a clipping distortion detection signal that identifies the occurrence of excessive clipping distortion over an adjustable maximum percent distortion, said system comprising:
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an audio amplifier having an input for receiving an input voltage, a voltage gain, and an output for providing an amplifier output voltage; a supply voltage supplied to said audio amplifier, said supply voltage determining a maximum amplifier output voltage limit; means for generating a comparison voltage which is indicative of the amplifier output voltage divided by the voltage gain; a clip detector comparator having a first input for receiving the input voltage and a second input for receiving the comparison voltage; a controllable voltage offset window associated with said comparator; and a current control circuit for generating a control signal to control the voltage offset window as a function of the supply voltage so as to achieve an adjustable maximum distortion level. - View Dependent Claims (7)
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8. A method of producing a clipping distortion detect signal which identifies the occurrence of excessive clipping distortion over an adjustable maximum percent distortion level, said method comprising:
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supplying a voltage signal to an audio amplifier, said voltage signal determining a maximum amplifier output voltage; applying an input signal to the audio amplifier to generate an amplified output signal as a function of amplifier voltage gain; generating a comparison voltage which is indicative of the output voltage divided by the amplifier voltage gain; comparing the input voltage with the comparison voltage and providing a clipping distortion detect output signal when the input voltage deviates from the comparison voltage in excess of an offset voltage which is indicative of excessive clipping distortion; and adaptively selecting the offset voltage as a function of the supply voltage so as to achieve an adjustable maximum percent distortion. - View Dependent Claims (9, 10, 11)
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Specification