Abstract: A method generates a reference voltage by steps including: generating a reference signal from a voltage source; generating a comparison signal of the reference signal with a voltage reference; sampling the comparison signal; adjusting a numerical value as a function of the result of the comparison and of the numerical value; and converting the current numerical value into a voltage corresponding to the reference voltage.

Abstract: A method generates a reference voltage by steps including: generating a reference signal from a voltage source; generating a comparison signal of the reference signal with a voltage reference; sampling the comparison signal; adjusting a numerical value as a function of the result of the comparison and of the numerical value; and converting the current numerical value into a voltage corresponding to the reference voltage.

Abstract: A method and corresponding circuit that adjusts the gain of an audio output stage having a class D amplifier, this method including the steps of setting the gain to a nominal value, analyzing an output signal during successive clock periods, counting the number of clock periods during which the signal is in a state corresponding to a saturation, decreasing the gain if the number reaches, before the end of a first time interval, a value corresponding to a first percentage, maintaining the gain constant if, at the end of a second time interval, different from the first interval, the number corresponds to a second percentage being comprised between the first percentage and a third percentage, and increasing the gain if, at the end of the second time interval, the number corresponds to a fourth percentage, lower than the third percentage.

Abstract: A method and corresponding circuit that adjusts the gain of an audio output stage having a class D amplifier, this method including the steps of setting the gain to a nominal value, analyzing an output signal during successive clock periods, counting the number of clock periods during which the signal is in a state corresponding to a saturation, decreasing the gain if the number reaches, before the end of a first time interval, a value corresponding to a first percentage, maintaining the gain constant if, at the end of a second time interval, different from the first interval, the number corresponds to a second percentage being comprised between the first percentage and a third percentage, and increasing the gain if, at the end of the second time interval, the number corresponds to a fourth percentage, lower than the third percentage.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.