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US 10,079,578 B2Granted
Total harmonic distortion (THD) controlled clip detector and automatic gain limiter (AGL)
AssigneeTexas Instruments Incorporated
InventorsShun Qian, Kim Nordtorp Madsen, Lucia Wan
Life of this patent
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Abstract
The disclosed embodiments include an audio amplifier system configured to provide a total harmonic distortion (THD) controlled clip detector and an automatic gain limiter (AGL) solution for a closed-loop amplifier. The audio amplifier system is capable of maintaining high power output without hard distortion (i.e., hard clipping) for providing better acoustics, while preventing damage to the system.
Claims15
An audio amplifier system comprising:
- an attenuator configured to adjust an electrical signal to generate an attenuated signal;
- an amplifier coupled to the attenuator and configured to amplify and modulate the attenuated signal;
- a voltage controlled current source (VCCS) coupled to the amplifier and configured to generate a feedback clip error signal;
- a clip detector configured to generate a clip indication signal, wherein the clip detector comprises:
- a sense resistor and a feedback resistor configured to generate an overdrive voltage based on the feedback clip error signal;
- a multiplexer configured to select one of a power supply voltage (PVCC) and a predetermined voltage reference (VREF) as a reference source;
- a voltage divider configured to receive the reference source to generate a scaled reference voltage;
- and
- a comparator configured to compare the overdrive voltage and the scaled reference voltage to generate a relative overdrive signal.
6 more elements
A clip detector comprising:
- a sense resistor and a feedback resistor configured to generate an overdrive voltage based on a feedback clip error signal;
- a multiplexer configured to select one of a power supply voltage (PVCC) and a predetermined voltage reference (VREF) as a reference source;
- a voltage divider configured to receive the reference source to generate a scaled reference voltage;
- a comparator configured to compare the overdrive voltage and the scaled reference voltage to generate a relative overdrive signal;
- and
- a debouncer configured to filter the relative overdrive signal to reduce noise and generate a clip indication signal.
3 more elements
An audio amplifier system comprising:
- an attenuator configured to adjust an electrical signal to generate an attenuated signal;
- a closed-loop class D amplifier configured to receive the attenuated signal, a feedback output signal of the closed-loop class D amplifier, and a feedback clip error signal as input;
- a voltage controlled current source (VCCS) coupled to the closed-loop class D amplifier and configured to generate the feedback clip error signal;
- and
- a clip detector configured to receive the feedback clip error signal, and generate a clip indication signal;
- wherein the clip detector comprises:
- a sense resistor and a feedback resistor configured to generate an overdrive voltage based on the feedback clip error signal;
- a multiplexer configured to select one of a power supply voltage (PVCC) and a predetermined voltage reference (VREF) as a reference source;
- a voltage divider configured to receive the reference source to generate a scaled reference voltage;
- a comparator configured to compare the overdrive voltage and the scaled reference voltage to generate a relative overdrive signal;
- and
- a debouncer configured to filter the relative overdrive signal to reduce noise and generate the clip indication signal.
9 more elements
A method for controlling a total harmonic distortion output of an audio system, the method comprising:
- generating an amplified error signal;
- generating a feedback clip error signal by comparing the amplified error signal to a stable reference signal;
- generating an overdrive voltage based on the feedback clip error signal using a sense resistor and a feedback resistor;
- generating a scaled reference voltage using a voltage divider and a reference source;
- generating a relative overdrive signal based on the overdrive voltage and the scaled reference voltage;
- generating a clip indication signal by filtering the relative overdrive signal to reduce noise;
- and
- controlling a maximum output power and total harmonic distortion (THD) through internal or external signal attenuation based on the clip indication signal.
5 more elements
Dependencies are inferred from the claim text.