Stmicroelectronics S.a.

Stmicroelectronics Gmbh

Nicolas Marty

Marco Cioci

R&eacute;gis Robert

An audio amplification device includes an input for receiving an input audio signal and an output for delivering an output audio signal and an amplifier (OA) comprising a differential pair of MOS transistors. The gate of the first transistor is coupled to the input of the device. The gate of the second MOS transistor receives a reference voltage which takes the form of a rising ramp when the power is turned on. The drain of one of the transistors is coupled to the output. The amplifier also includes a biasing circuitry for biasing the bulk of the transistors to a first voltage level approximately equal to a supply voltage at the beginning of the reference voltage ramp, and to a second voltage level (V) approximately equal to the voltage of their source at the end of the ramp. The generation of a pop is thus avoided when the power is turned on, while still benefiting from an optimum PSRR in the normal operation phase.

Audio amplification device with antipop circuitry

A control method and a linear regulator of the type including a power MOS transistor, controlled by a differential amplifier having a first input terminal receiving a reference voltage and a second input terminal receiving, via a switchable resistor circuit, the output voltage of the regulator, a smooth switching of the resistors being provided.

Linear regulator with a selectable output voltage

A voltage regulator includes a power transistor for providing an electrical current to a load circuit connected to an output of the regulator. The delivered current is limited by a limitation circuit within the regulator. A stabilization resistor is connected between the power transistor and the output of the regulator. The limitation circuit includes a fixed-voltage generator, and a comparator for comparing the voltage generated in the stabilization resistor by the output current of the regulator with the fixed voltage. The output of the comparator controls an adjustment transistor that limits the current delivered by the power transistor.

Voltage regulator incorporating a stabilization resistor and a circuit for limiting the output current

A voltage regulating device includes a comparison circuit for comparing a voltage proportional to an output voltage to a fixed reference voltage. The fixed reference voltage is received on a first input and the voltage proportional to an output voltage is received on a second input. The voltage regulating device further includes a variable resistance-forming circuit controlled by the output of the comparison circuit and disposed so that the output voltage remains substantially constant. The voltage regulating device may be supplied with a variable input voltage. The voltage regulating device further includes a second comparison circuit so that the output voltage remains substantially constant if the input voltage is greater than a threshold, and substantially equal to the input voltage if the input voltage is less than the threshold.

Voltage regulating device and process

A voltage regulator includes a regulation MOS transistor and an amplifier providing an output for driving a gate of the regulation MOS transistor. The amplifier drives the gate based upon a difference between a reference voltage and a feedback voltage. The voltage regulator may further include a circuit for making the amplifier switch to a standby mode with low current consumption when the difference between the supply voltage and the output voltage of the regulator is below a first threshold. This is done while maintaining, at the gate of the regulation transistor, a voltage that keeps the regulation transistor on. The present invention is particularly applicable to the management of power supplies in portable telephones.

Low electrical consumption voltage regulator

A linear regulator of the type including a power MOS transistor of a first channel type, controlled by an amplifier having an output stage including, between two supply terminals, a resistor and a first MOS control transistor of a second channel type. The regulator further includes a start-up circuit having a switchable resistor in parallel on said first resistor.

Linear regulator with a low series voltage drop

A voltage regulator includes a regulation MOS transistor with low serial resistance having a first terminal connected to a voltage source and a second terminal connected to the output of the voltage regulator and an amplifier having an output driving a gate of the transistor. The gate is driven based upon a difference between a reference voltage and a feedback voltage. The regulator may also include an anti-overshoot switch with a first terminal connected to the gate of the regulation MOS transistor and a second terminal is taken to a potential for turning the regulation MOS transistor off. A switch controller closes the switch when the output voltage of the regulator is higher than a first threshold. The first threshold may be higher than the nominal value of the output voltage.

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Claix, France

Nicolas Marty