St-Ericsson Sa

Francois Amiard

Emmanuel Allier

Vincent Binet

Remy Cellier

There is disclosed a driver circuit for a power amplifier of class D type having a segmented architecture with at least one current branch which can be powered down in a low power mode of operation of the circuit. The branch comprising a switch with a cascode MOS transistor, the circuit further comprises a bias circuitry adapted for dynamically generating a dynamic bias control signal so as to cause the cascode MOS transistor of the switch to be 'Off' in the low power mode.

Cascode bias of power MOS transistors

An audio amplification circuit comprises an amplifier having an input and an output, as well as an audio output to which a load can be connected. It additionally comprises a first driver stage having an input and an output which is not coupled to the audio output, and a second driver stage having an input and an output which is coupled to the audio output. The output from the amplifier is selectively coupled to the input of the first driver stage in a first phase of operation and then selectively to the input of the second driver stage in a second phase of operation following the first phase of operation.

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Grenoble, France

Francois Amiard