Feedback amplifier
First Claim
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1. A signal amplifier comprising:
- a class D amplifier generating a modulated voltage signal switching as a function of an intermediate signal;
a low-pass filter input with the modulated voltage signal for applying a filtered replica of the modulated voltage signal to a load;
a plurality of feedback paths for generating a plurality of feedback signals of the filtered replica; and
a circuit input with the plurality of feedback signals of the filtered replica and a signal to be amplified and generating the intermediate signal as a combination of the plurality of feedback signals, the signal to be amplified, and an externally generated reference carrier;
said plurality of feedback paths including respective feedback filters, each feedback filter for compensating a respective frequency pole of a transfer function of a cascade of the low-pass filter with the load and for establishing at least one band pass of the signal amplifier.
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Abstract
A feedback architecture for a PWM switching audio amplifier is, capable of compensating the effects of the demodulation filter through at least two feedback paths of the voltage applied to a load without degrading the overall loop gain of the device. Each of the feedback paths may include a respective network or filter for compensating a respective frequency pole of the cascade low-pass filter+load and establishing a certain band pass. These networks or filters may be passive networks.
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Citations
12 Claims
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1. A signal amplifier comprising:
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a class D amplifier generating a modulated voltage signal switching as a function of an intermediate signal; a low-pass filter input with the modulated voltage signal for applying a filtered replica of the modulated voltage signal to a load; a plurality of feedback paths for generating a plurality of feedback signals of the filtered replica; and a circuit input with the plurality of feedback signals of the filtered replica and a signal to be amplified and generating the intermediate signal as a combination of the plurality of feedback signals, the signal to be amplified, and an externally generated reference carrier; said plurality of feedback paths including respective feedback filters, each feedback filter for compensating a respective frequency pole of a transfer function of a cascade of the low-pass filter with the load and for establishing at least one band pass of the signal amplifier. - View Dependent Claims (2, 3, 4)
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5. A signal amplifier comprising:
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an amplifier generating a modulated signal based upon an intermediate signal; a filter having an input coupled to the modulated signal, and an output coupled to a load; a plurality of feedback paths coupled to the output of said filter; and a circuit coupled to said plurality of feedback paths for generating the intermediate signal based upon a combination of an input signal, outputs of said plurality of feedback paths, and a reference signal; said plurality of feedback paths including respective feedback filters, each feedback filter for compensating a respective frequency pole of a transfer function of said filter coupled to the load. - View Dependent Claims (6, 7, 8)
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9. A method for making a signal amplifier comprising an amplifier generating a modulated signal based upon an intermediate signal, and a filter having an input coupled to the modulated signal and an output coupled to a load, the method comprising:
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coupling a plurality of feedback paths to the output of the filter; and coupling an input of a circuit with the plurality of feedback paths for generating the intermediate signal based upon a combination of an input signal, outputs of the plurality of feedback paths, and a reference signal; the plurality of feedback paths including respective feedback filters, each feedback filter for compensating a respective frequency pole of a transfer function of the filter coupled to the load. - View Dependent Claims (10, 11, 12)
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Specification