Abstract: In an embodiment an electronic device includes a first electronic circuit having a capacitive element with a variable capacitance, wherein the first electronic circuit is configured to couple the capacitive element to an antenna, to measure, by successive iterations, a first analog signal representative of a variation of an instantaneous electric power received by the antenna or representative of the instantaneous electric power received by the antenna and to modify the capacitance of the capacitive element until an amplitude of the instantaneous electric power received by the antenna is a maximum, wherein the antenna is configured to capture an amplitude-modulated electromagnetic field.

Abstract: An amplification circuit includes an amplifier circuit (provided by an operational amplifier) that amplifies a signal to be demodulated. A feedback loop of the amplification circuit has a resistance value that is controlled to discretely vary according to a level of an output node of the amplifier circuit. A comparison of the output level with respect to one or a plurality of thresholds, which define out-of-saturation operating ranges of the amplifier circuit, drives selection of the resistance value.

Abstract: The present disclosure concerns an electronic device connected to an antenna. The electronic device delivers a first amplitude-modulated analog signal of a signal captured by the antenna, the capture signal associated with an electromagnetic field exhibiting intervals at a minimum level. The electronic device includes a first circuit, a second circuit, and a third circuit. The first circuit delivers a second analog signal by rectification and filters the first analog signal. The second circuit delivers a first binary signal based on the demodulation of the second analog signal. The third circuit couples the antenna to a resistor during each pause. The resistance value of the resistor depends on the maximum amplitude of the electromagnetic field before the pause.

Abstract: The present description concerns an integrated circuit including, between first and second terminals having a first voltage applied therebetween, a load configured to execute instructions, a circuit for delivering a digital signal having at least two bits from a binary signal and a current output digital-to-analog converter controlled by the digital signal and coupled between the first and second terminals in parallel with the load.

Abstract: An electronic circuit includes a reference voltage circuit and a circuit for checking the starting operation of the reference voltage circuit. The reference voltage circuit includes a first stack of a first transistor and second transistor receiving first and second control signals, respectively. The start check circuit includes a first elementary test circuit including a second stack of a third transistor and fourth transistor receiving the first and second control signals, respectively. An output of the first elementary test circuit delivers a first binary signal indicative of proper starting operation of the reference voltage circuit.

Abstract: An electronic circuit includes a reference voltage circuit and a circuit for checking the starting operation of the reference voltage circuit. The reference voltage circuit includes a first stack of a first transistor and second transistor receiving first and second control signals, respectively. The start check circuit includes a first elementary test circuit including a second stack of a third transistor and fourth transistor receiving the first and second control signals, respectively. An output of the first elementary test circuit delivers a first binary signal indicative of proper starting operation of the reference voltage circuit.

Abstract: In an embodiment an electronic device includes a first electronic circuit having a capacitive element with a variable capacitance, wherein the first electronic circuit is configured to couple the capacitive element to an antenna, to measure, by successive iterations, a first analog signal representative of a variation of an instantaneous electric power received by the antenna or representative of the instantaneous electric power received by the antenna and to modify the capacitance of the capacitive element until an amplitude of the instantaneous electric power received by the antenna is a maximum, wherein the antenna is configured to capture an amplitude-modulated electromagnetic field.

Abstract: A contactless communication method comprises retro-modulation of a carrier signal received at the terminals of an antenna in an alternation of modulated states and unmodulated states. The modulated state comprises a modulation of a load at the terminals of the antenna at zero impedance, and the transitions from the modulated state to the unmodulated state are controlled at an instant determined by a first delay.

Abstract: The present disclosure concerns an electronic device connected to an antenna. The electronic device delivers a first amplitude-modulated analog signal of a signal captured by the antenna, the capture signal associated with an electromagnetic field exhibiting intervals at a minimum level. The electronic device includes a first circuit, a second circuit, and a third circuit. The first circuit delivers a second analog signal by rectification and filters the first analog signal. The second circuit delivers a first binary signal based on the demodulation of the second analog signal. The third circuit couples the antenna to a resistor during each pause. The resistance value of the resistor depends on the maximum amplitude of the electromagnetic field before the pause.

Abstract: A method for limiting voltage at an input of an integrated circuit of a transponder contactlessly communicating with a reader includes, during the contactless communication: receiving a carrier signal at an antenna of the transponder; and controlling gate voltages of two transistors of a rectifier circuit of the transponder so as to modify an input impedance of the integrated circuit, wherein the two transistors are cross-coupled between terminals of the antenna and a reference voltage.

Abstract: A contactless communication method comprises retro-modulation of a carrier signal received at the terminals of an antenna in an alternation of modulated states and unmodulated states. The modulated state comprises a modulation of a load at the terminals of the antenna at zero impedance, and the transitions from the modulated state to the unmodulated state are controlled at an instant determined by a first delay.

Abstract: The present description concerns an integrated circuit including, between first and second terminals having a first voltage applied therebetween, a load configured to execute instructions, a circuit for delivering a digital signal having at least two bits from a binary signal and a current output digital-to-analog converter controlled by the digital signal and coupled between the first and second terminals in parallel with the load.

Abstract: A contactless card is powered by an antenna connected to the input of a rectifier. An output of the rectifier is coupled to a processing unit that consumes a first current output from the rectifier. A current regulation circuit is connected to the output of the rectifier. The current regulation circuit operates to absorb a second current from the output of the rectifier such that a sum of the first and second currents is a constant current.

Abstract: A method for limiting voltage at an input of an integrated circuit of a transponder contactlessly communicating with a reader includes, during the contactless communication: receiving a carrier signal at an antenna of the transponder; and controlling gate voltages of two transistors of a rectifier circuit of the transponder so as to modify an input impedance of the integrated circuit, wherein the two transistors are cross-coupled between terminals of the antenna and a reference voltage.

Abstract: A contactless card is powered by an antenna connected to the input of a rectifier. An output of the rectifier is coupled to a processing unit that consumes a first current output from the rectifier. A current regulation circuit is connected to the output of the rectifier. The current regulation circuit operates to absorb a second current from the output of the rectifier such that a sum of the first and second currents is a constant current.

Abstract: A contactless card is powered by an antenna connected to the input of a rectifier. An output of the rectifier is coupled to a processing unit that consumes a first current output from the rectifier. A current regulation circuit is connected to the output of the rectifier. The current regulation circuit operates to absorb a second current from the output of the rectifier such that a sum of the first and second currents is a constant current.

Abstract: A contactless card is powered by an antenna connected to the input of a rectifier. An output of the rectifier is coupled to a processing unit that consumes a first current output from the rectifier. A current regulation circuit is connected to the output of the rectifier. The current regulation circuit operates to absorb a second current from the output of the rectifier such that a sum of the first and second currents is a constant current.

Abstract: A delta-sigma analog-to-digital converter generates a digital signal as a function of an analog signal and a clock signal having a first phase and a second phase. The converter includes a first branch that applies an analog input signal, a feedback branch having a digital-to-analog converter that feeds back an analog reference signal, a loop filter, a quantizer, and a switch. The switch includes, and is timely correlated with, an output switch of the digital-to- analog converter. The switch functions to connect an input resistance on the first branch and disconnect the digital-to-analog converter during the first phase, and disconnects the input resistance and connects the digital-to-analog converter during the second phase.

Abstract: The present invention relates to analog-to-digital converters and more particularly to a delta-sigma analog-to-digital converter 1 for generating a digital signal as a function of an analog signal and a clock signal having a first phase and a second phase, said converter comprises:—a first branch 11 for applying an analog input signal,—a feedback branch for feeding back an analog reference signal, with a digital-to-analog converter 121,—a loop filter 13,—a quantizer 15, and—a switch 16, the switch being arranged and timely correlated with an output switch of said digital-to-analog converter in order to connect the input resistance and disconnect the digital-to-analog converter during said first phase and to disconnect the input resistance and connect the digital-to-analog converter during said second phase. The present invention also relates to a method for operating the same.