Input clamping structure for sound quality improvement in car-radio class-AB power amplifier design
AssigneeSTMicroelectronics (Shenzhen) R&D Co. Ltd
InventorsMei Yang, YueHua Wang, Xaut Zhang, Kelvin Wen, XiangSheng Li
Life of this patent
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Abstract
A clamping circuit for a class AB amplifier includes a reference voltage circuit, four NPN Darlington transistors having inputs coupled to the reference voltage circuit, and outputs for providing four clamped voltages and a split NPN Darlington transistor having an input coupled to the reference voltage circuit, and four separate outputs for providing four AC ground voltages.
Claims24
An AB amplifier circuit comprising:
- a plurality of AB amplifiers;
- a plurality of Darlington transistors having a plurality of inputs coupled to a reference voltage, and a plurality of outputs configured to provide a plurality of clamped voltages to the plurality of AB amplifiers;
- and
- a split Darlington transistor comprising
- a first transistor and a second transistor coupled together in a Darlington configuration, and
- at least one third transistor coupled to the second transistor,
- the first transistor, second transistor and at least one third transistor having inputs coupled to the reference voltage,
- the second transistor and at least one third transistor having a plurality of outputs configured to provide a plurality of AC ground voltages to the plurality of AB amplifiers.
An electronic device comprising:
- a plurality of AB amplifiers;
- a plurality of NPN Darlington transistors having a plurality of inputs coupled to a reference voltage, and a plurality of outputs configured to provide a plurality of clamped voltages to the plurality of AB amplifiers;
- and
- a split NPN Darlington transistor comprising
- a first transistor and a second transistor coupled together in a Darlington configuration, and
- at least one third transistor coupled to the second transistor,
- the first transistor, second transistor and at least one third transistor having inputs coupled to the reference voltage,
- the second transistor and at least one third transistor having a plurality of outputs configured to provide a plurality of AC ground voltages to the plurality of AB amplifiers.
A method of operating a plurality of AB amplifiers arranged in pairs with each pair comprising a clamp input and an AC ground input, the method comprising:
- operating a plurality of Darlington transistors having a plurality of inputs coupled to a reference voltage, and a plurality of outputs providing a plurality of clamped voltages to the clamp inputs of the plurality of AB amplifiers;
- and
- operating a split Darlington transistor comprising
- a first transistor and a second transistor coupled together in a Darlington configuration, and
- at least one third transistor coupled to the second transistor,
- the first transistor, second transistor and at least one third transistor having inputs coupled to the reference voltage,
- the second transistor and at least one third transistor having a plurality of outputs providing a plurality of AC ground voltages to the AC ground inputs of the plurality of AB amplifiers.
Dependencies are inferred from the claim text.