Abstract: In accordance with an embodiment, a linear voltage regulator includes: a first transistor coupled between a first input terminal and an output terminal, the first input terminal adapted to receive a first voltage, and the output terminal adapted to provide a regulated voltage; a second transistor coupled between a second input terminal and the output terminal, the second input terminal adapted to receive a second voltage; and an amplifier of a difference between a third voltage proportional to the voltage at the output terminal and a reference voltage, an output of said amplifier being selectively coupled to a control terminal of the first transistor and to a control terminal of the second transistor, the amplifier being supplied by a fourth voltage corresponding to a highest voltage of the first voltage and the second voltage.

Abstract: In accordance with an embodiment, a linear voltage regulator includes: a first transistor coupled between a first input terminal and an output terminal, the first input terminal adapted to receive a first voltage, and the output terminal adapted to provide a regulated voltage; a second transistor coupled between a second input terminal and the output terminal, the second input terminal adapted to receive a second voltage; and an amplifier of a difference between a third voltage proportional to the voltage at the output terminal and a reference voltage, an output of said amplifier being selectively coupled to a control terminal of the first transistor and to a control terminal of the second transistor, the amplifier being supplied by a fourth voltage corresponding to a highest voltage of the first voltage and the second voltage.

Abstract: A communication device (10) comprises a conductor (11), a transceiver (12) coupled to the conductor (11) and a data processing unit (13) that is coupled to the transceiver (12). The communication device (10) is configured to determine a strength signal (ST) depending on a receiver signal (SR) received via the conductor (11) and to determine a proximity signal (SP) depending on a proximity of a body to the communication device (10). The data processing unit (13) is configured to generate a disable signal (STO) depending on at least a value of the strength signal (ST) and on at least a value of the proximity signal (SP).

Abstract: A demodulator circuit receives an envelope signal for comparison against a switched reference signal that is generated as a function of the envelope signal and as a function of an output signal of the demodulator circuit. The switched reference signal is filtered by an RC filter prior to comparison. The output signal is dependent on a difference between the filtered switched reference signal and the envelope signal.

Abstract: A reader is adapted to wirelessly exchanging information with a wireless apparatus. The reader includes a signal generator configured to generate a modulation signal. An emitter/receptor stage is configured to be driven by the modulation signal. A switched-mode power supply is configured to power the emitter/receptor stage. The switched-mode power supply includes a power switch controlled in function of the modulation signal.

Abstract: An RFID transponder device has antenna terminals for coupling an antenna system to the device. A transmitter and a receiver are coupled to the antenna terminals. The device has at least one damping resistance connected to at least one of the antenna terminals. The at least one damping resistance is connected, depending on a voltage swing at the antenna terminals during a transmission burst period, either together with a serially connected switch in parallel to the antenna terminals that are coupled to the receiver, or together with a parallel connected switch between one of the antenna terminals and a terminal of the transmitter. A damping control is configured to activate the at least one damping resistance during a damping period after the transmission burst period by controlling the respective switch.

Abstract: In an embodiment, a carrier signal generation circuit can be used for a Radio-frequency identification (RFID) transponder device. A frequency divider circuit has a first input to receive a first frequency signal, a second input to receive a division ratio signal, and an output to provide a carrier signal as a function of the first frequency signal and the division ratio signal. A phase difference circuit has a first input to receive an analog reader device carrier signal, a second input to receive a signal based on the first frequency signal and an output to provide a digital phase difference signal as a function of the reader device carrier signal and the signal based on the first frequency signal. A signal processor has an input coupled to the output of the phase difference circuit.

Abstract: A communication device (10) comprises a conductor (11), a transceiver (12) coupled to the conductor (11) and a data processing unit (13) that is coupled to the transceiver (12). The communication device (10) is configured to determine a strength signal (ST) depending on a receiver signal (SR) received via the conductor (11) and to determine a proximity signal (SP) depending on a proximity of a body to the communication device (10). The data processing unit (13) is configured to generate a disable signal (STO) depending on at least a value of the strength signal (ST) and on at least a value of the proximity signal (SP).

Abstract: A circuit includes an antenna circuit including a number of capacitors and an inductor. The antenna circuit is configured to transmit an output signal upon receiving an input transmit signal. A first control block is configured to transmit an enabling signal upon detecting a presence of a supply voltage at a feeding terminal of the actively transmitting tag in response to the actively transmitting tag being inserted into a host device. A VCO is configured to generate the input transmit signal with the frequency of the interrogator carrier signal upon receiving the enabling signal from the first control block and upon receiving the control voltage from the memory. A second control block is configured to enable a subset of the plurality of capacitors of the antenna circuit upon receiving the enabling signal from the first control block.

Abstract: A demodulator circuit receives an envelope signal for comparison against a switched reference signal that is generated as a function of the envelope signal and as a function of an output signal of the demodulator circuit. The switched reference signal is filtered by an RC filter prior to comparison. The output signal is dependent on a difference between the filtered switched reference signal and the envelope signal.

Abstract: A circuit of an actively transmitting tag includes an antenna, a digitizer, a voltage-controlled oscillator (VCO), an output amplifier, a phase-displacement detector, and a regulator. The input of the digitizer connects to the antenna. The outputs of the digitizer and the output amplifier are connected to the input terminals of the phase-displacement detector. The output amplifier connects the output of the VCO to the antenna and the regulator connects the output of the phase-displacement detector to the VCO.

Abstract: A circuit includes an antenna circuit including a number of capacitors and an inductor. The antenna circuit is configured to transmit an output signal upon receiving an input transmit signal. A first control block is configured to transmit an enabling signal upon detecting a presence of a supply voltage at a feeding terminal of the actively transmitting tag in response to the actively transmitting tag being inserted into a host device. A VCO is configured to generate the input transmit signal with the frequency of the interrogator carrier signal upon receiving the enabling signal from the first control block and upon receiving the control voltage from the memory. A second control block is configured to enable a subset of the plurality of capacitors of the antenna circuit upon receiving the enabling signal from the first control block.

Abstract: An RFID transponder device has antenna terminals for coupling an antenna system to the device. A transmitter and a receiver are coupled to the antenna terminals. The device has at least one damping resistance connected to at least one of the antenna terminals. The at least one damping resistance is connected, depending on a voltage swing at the antenna terminals during a transmission burst period, either together with a serially connected switch in parallel to the antenna terminals that are coupled to the receiver, or together with a parallel connected switch between one of the antenna terminals and a terminal of the transmitter. A damping control is configured to activate the at least one damping resistance during a damping period after the transmission burst period by controlling the respective switch.

Abstract: According to an embodiment, a method can be performed by a first active near-field communication (NFC) device. The method includes assuming a field detection mode, generating an advertisement pulse, and checking whether a predefined condition is fulfilled. If the checking determines that the predefined condition is fulfilled, the method includes assuming an active mode and communicating with an adjacent active NFC device, and, if the checking does not determine that the predefined condition is fulfilled, the method includes staying in the field detection mode and generating another advertisement pulse.

Abstract: Tuning an antenna circuit of an actively transmitting tag to a frequency of an interrogator carrier signal after the tag was inserted into a host device is accomplished by detecting presence of the interrogator carrier signal at a location of the actively transmitting tag and hereafter setting capacitances of capacitors and/or inductances of coils comprised in said antenna circuit in a way that resonance of said antenna circuit is established while the antenna circuit is excited by a magnetic field of said interrogator carrier signal. This allows automatic tuning of an antenna circuit of an actively transmitting tag after it was inserted together with a miniature card into a host device, such as a mobile telephone, personal digital assistant, tablet PC and similar devices.

Abstract: A radio frequency system has a first and a second antenna terminal, a radio frequency transceiver coupled to the antenna terminals, a rectifier connected to the antenna terminals at its input side and a voltage limiter. The voltage limiter comprises a first and a second input terminal connected to the antenna terminals, and a first and a second diode element connected between the first respectively the second input terminal and a bias terminal. A regulation transistor is connected between the bias terminal and the reference potential terminal. A voltage controller has a reference input for receiving a reference signal, a feedback input connected to the bias terminal and a control output for providing a control potential to a control terminal of the regulation transistor on the basis of the reference signal and a signal at the bias terminal.

Abstract: An RFID transponder device has antenna terminals for coupling an antenna system to the device. A transmitter and a receiver are coupled to the antenna terminals. The device has at least one damping resistance connected to at least one of the antenna terminals. The at least one damping resistance is connected, depending on a voltage swing at the antenna terminals during a transmission burst period, either together with a serially connected switch in parallel to the antenna terminals that are coupled to the receiver, or together with a parallel connected switch between one of the antenna terminals and a terminal of the transmitter. A damping control is configured to activate the at least one damping resistance during a damping period after the transmission burst period by controlling the respective switch.

Abstract: In an embodiment, a carrier signal generation circuit can be used for a Radio-frequency identification (RFID) transponder device. A frequency divider circuit has a first input to receive a first frequency signal, a second input to receive a division ratio signal, and an output to provide a carrier signal as a function of the first frequency signal and the division ratio signal. A phase difference circuit has a first input to receive an analog reader device carrier signal, a second input to receive a signal based on the first frequency signal and an output to provide a digital phase difference signal as a function of the reader device carrier signal and the signal based on the first frequency signal. A signal processor has an input coupled to the output of the phase difference circuit.

Abstract: According to an embodiment, a method can be performed by a first active near-field communication (NFC) device. The method includes assuming a field detection mode, generating an advertisement pulse, and checking whether a predefined condition is fulfilled. If the checking determines that the predefined condition is fulfilled, the method includes assuming an active mode and communicating with an adjacent active NFC device, and, if the checking does not determine that the predefined condition is fulfilled, the method includes staying in the field detection mode and generating another advertisement pulse.

Abstract: A circuit of an actively transmitting tag includes an antenna, a digitizer, a voltage-controlled oscillator (VCO), an output amplifier, a phase-displacement detector, and a regulator. The input of the digitizer connects to the antenna. The outputs of the digitizer and the output amplifier are connected to the input terminals of the phase-displacement detector. The output amplifier connects the output of the VCO to the antenna and the regulator connects the output of the phase-displacement detector to the VCO.