Stmicroelectronics S.a.

Schneider Electric Industries Sas

Robert Cittadini

Christophe Forel

Bruno Beranger

Oleg Garelli

An inhibit circuit which produces an inhibit signal when a variation in a power supply potential is detected includes a comparator having a negative input connected to a generator producing a reference potential and a positive input connected to an output of a first image circuit producing a first potential that is an image of the power supply potential. The first image circuit includes a diode and a circuit for the production of a reference current parallel-connected between a common point to which the power supply potential is applied and an output of the first image circuit connected to the positive input of the comparator. The circuit has particular utility in portable integrated circuits with very low consumption when idle such as in mobile telephony.

Low-consumption inhibit circuit with hysteresis

A power amplifier circuit including first and second cascade-assembled operational amplifiers having respective first inputs receiving a reference voltage across a decoupling capacitor, respective outputs of which are connected across a load and are looped back on respective second inputs, the second input of the first amplifier receiving, from a coupling capacitor, an input voltage to be amplified, the amplifier circuit including means for separately charging the coupling and decoupling capacitors, upon circuit power-on, from an off or standby state, and means for inhibiting the amplifiers at least during the separate charging.

Audio amplifier circuit with suppression of unwanted noise when starting from an off or standby state

The coupling device comprises a transformer having a primary winding in series with a two-way switch controlled via an optocoupler and a three-position selector switch by a control circuit. In standby mode, the switch is connected to an oscillator defining a switching frequency (49 kHz) ensuring power supply of the control circuit, which circuit is able to detect the presence of a carrier on the transformer secondary winding. In receipt mode, the switch is closed and the control circuit analyzes the modulated information received on the transformer secondary winding. In transmission mode, the control circuit causes switching of the switch at the information modulation frequency (132 khz), performing both power supply of the control circuit and transmission of the information.

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Grenoble, France

Robert Cittadini