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US 10,944,366 B2Granted
Advanced load current monitoring circuit and method for a class-AB amplifier
AssigneeSTMicroelectronics (Shenzhen) R&D Co. Ltd
InventorsRu Feng Du, XiangSheng Li
Life of this patent
Estimating the term…
Abstract
In an embodiment, a class-AB amplifier includes: an output stage that includes a pair of half-bridges configured to be coupled to a load; and a current sensing circuit coupled to a first half-bridge of the pair of half-bridges. The current sensing circuit includes a resistive element and is configured to sense a load current flowing through the load by: mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current, flowing the mirrored current through the resistive element, and sensing the load current based on a voltage of the resistive element.
Claims29
A class-AB amplifier comprising:
- an output stage that comprises a pair of half-bridges configured to be coupled to a load;
- and
- a current sensing circuit having a high impedance input coupled to a first half-bridge of the pair of half-bridges, the current sensing circuit comprising a resistive element and configured to sense a load current flowing through the load by:
- mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current based on the high impedance input of the current sensing circuit,
- flowing the mirrored current through the resistive element, and
- sensing the load current based on a voltage of the resistive element, wherein the mirrored current is configured to flow through a path different from the load.
3 more elements
A class-AB amplifier comprising:
- an output stage that comprises a pair of half-bridges configured to be coupled to a load;
- and
- a current sensing circuit coupled to a first half-bridge of the pair of half-bridges, the current sensing circuit comprising a resistive element and configured to sense a load current flowing through the load by:
- mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current,
- flowing the mirrored current through the resistive element, and
- sensing the load current based on a voltage of the resistive element, wherein the current sensing circuit further comprises:
- a second transistor having a control terminal coupled to an output of the first half-bridge;
- a third transistor having a control terminal coupled to a current path of the second transistor;
- a sense transistor having a control terminal coupled to a control terminal of the first transistor and having a current path coupled to a current path of the third transistor;
- and
- a current mirror coupled between the sense transistor and the resistive element, the current mirror configured to generate the mirrored current.
8 more elements
A class-AB amplifier comprising:
- an output stage that comprises a pair of half-bridges configured to be coupled to a load;
- a current sensing circuit coupled to a first half-bridge of the pair of half-bridges, the current sensing circuit comprising a resistive element and configured to sense a load current flowing through the load by:
- mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current,
- flowing the mirrored current through the resistive element, and
- sensing the load current based on a voltage of the resistive element;
- an analog-to-digital converter (ADC) configured to generate a digital signal based on the voltage of the resistive element;
- a reference resistor;
- and
- a reference current source configured to inject a reference current into the reference resistor to generate a reference voltage, wherein the ADC is configured to receive the reference voltage, wherein the resistive element comprises a first resistor, and wherein the first resistor and the reference resistor are matching resistors.
6 more elements
A digital input class-AB amplifier comprising:
- an output stage that comprises a pair of half-bridges configured to be coupled to a load;
- a digital communication interface configured to receive an data stream;
- a digital core circuit;
- a digital-to-analog converter (DAC);
- a driver circuit configure to receive a signal from the DAC, and configured to control the output stage based on the received signal;
- a current sensing circuit coupled to a first half-bridge of the pair of half-bridges, the current sensing circuit comprising a resistive element and configured to sense a load current flowing through the load by:
- mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current,
- flowing the mirrored current through the resistive element, and
- sensing the load current based on a voltage of the resistive element;
- and
- an analog-to-digital converter (ADC) coupled to the digital core circuit and configured to generate a digital signal based on the sensed load current.
8 more elements
A method comprising:
- driving a load with a class-AB amplifier;
- mirroring a current flowing through a first transistor of an output stage of the class-AB amplifier to generate a mirrored current based on a high impedance input of a current sensing circuit coupled to the first transistor;
- flowing the mirrored current through a resistive element of the current sensing circuit;
- and
- sensing a load current flowing through the load based on a voltage of the resistive element, wherein the current sensing circuit further comprises:
- a second transistor having a control terminal coupled to the high impedance input of the current sensing circuit, and
- a third transistor having a control terminal coupled to a current path of the second transistor, wherein the mirrored current is based on a current flowing through a current path of the third transistor.
4 more elements
A digital input class-AB amplifier comprising:
- an output stage that comprises a pair of half-bridges configured to be coupled to an audio speaker;
- a digital communication interface configured to receive an audio stream;
- a digital core circuit;
- a digital-to-analog converter (DAC);
- a driver circuit configure to receive a signal from the DAC, and configured to control the output stage based on the received signal;
- a current sensing circuit comprising:
- a second transistor having a control terminal coupled to an output of a first half-bridge of the pair of half-bridges;
- a third transistor having a control terminal coupled to a current path of the second transistor;
- a first sense transistor having a control terminal coupled to a control terminal of a first transistor of the first half-bridge and having a current path coupled to a current path of the third transistor;
- a first resistor;
- a first current mirror coupled between the first sense transistor and the first resistor, the first current mirror configured to generate a first mirrored current that flows through the first resistor;
- a fourth transistor having a control terminal coupled to an output of a second half-bridge of the pair of half-bridges;
- a fifth transistor having a control terminal coupled to a current path of the fourth transistor;
- a second sense transistor having a control terminal coupled to a control terminal of a sixth transistor of the second half-bridge and having a current path coupled to a current path of the fifth transistor;
- a second resistor;
- a second current mirror coupled between the second sense transistor and the second resistor, the second current mirror configured to generate a second mirrored current that flows through the second resistor;
- and
- an analog-to-digital converter (ADC) coupled to the first and second resistors, the ADC configured to generate a digital signal based on voltage difference between a first node of the first resistor and a second node of the second resistor, wherein the digital core circuit is configured to estimate an impedance of the audio speaker based on the digital signal.
15 more elements
Dependencies are inferred from the claim text.