Nxp B.v.

Gertjan Van Holland

Fred Mostert

Paul Wielage

Jacobus Govert Sneep

Patrick John Zeelen

A method and apparatus of load detection for an audio amplifier system is described. A load detector includes a first load terminal and a second load terminal; a controller coupled to the first and second load terminals and configured to in a first control loop, vary a first current supplied to a first load terminal dependent on the difference between a first reference signal and the detected first load terminal voltage; and in a second control loop, vary a second current supplied to the second load terminal dependent on the difference between a second reference signal and the detected second load terminal voltage; and to determine a current through a load connected between the first load terminal and the second load terminal from the second current value, and a voltage across the load from the detected voltage difference between the first load terminal voltage and the second load terminal voltage.

Load detector

Embodiments of a driver circuit for a power stage of a class-D amplifier and a class-D amplifier are described. In one embodiment, a driver circuit for a power stage of a class-D amplifier includes serially connected transistor devices connected to a gate terminal of a power transistor of the power stage of the class-D amplifier, a voltage generator connected between a gate terminal of a first transistor device of the serially connected transistor devices and a source terminal of the power transistor, and a current multiplier connected between the gate terminal of the power transistor and one of a source terminal and a drain terminal of the first transistor device. The current multiplier is configured to produce an output current that is proportional to a current at the one of the source terminal and the drain terminal of the first transistor device.

Driver circuit for a power stage of a class-D amplifier

A 3-level class D amplifier circuit comprises a first comparator for comparing an input with a first triangular reference and a second comparator for comparing the input with a second triangular reference. A phase relationship between the signals to the first comparator is 180 degrees shifted relative to a phase relationship between the signals to the second comparator. An amplifier stage generates a three-level PWM output signal using the outputs of the first and second comparators. A shared feedback path is used from the three-level PWM output signal.

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Ede, Netherlands

Gertjan Van Holland