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: The disclosure relates to a modified NFC framing is used by a reader and selected devices during at least a part of the communication between the reader and the selected devices. The reader and the selected devices store modification rules for modifying the frames. Devices not storing those modification rules will discard the received modified frames.

Abstract: An embodiment device comprises a phase locked loop and a frequency locked loop having in common the same controlled oscillator. The device is firstly placed in the card emulation mode at the beginning of a communication between the contactless communication device and a contactless reader, the firstly placing comprising synchronizing within the contactless device, an ALM carrier frequency with a reader carrier frequency by operating at least the phase locked loop, and upon reception by the contactless communication device of an indication sent by the reader indicating a further communication in a peer to peer mode with the reader, the device is secondly placed in the peer to peer mode, the secondly placing including deactivating the phase locked loop and operating the frequency locked loop with a reference clock signal and a frequency set point depending on the reader carrier frequency and the frequency of the reference clock signal.

Abstract: A near-field communication circuit of a first NFC device alternates, in low power mode, between: first phases of emission of field bursts and second phases spanning an entire duration separating two successive first phases. Each second phase includes a field detector enabling phase. In one implementation, the field detector enabling phase extends all along a duration of the second phase. In an alternate implementation, the field detector enabling phase is interrupted by field detector disabling phases. Each field detector disabling phase has a duration shorter than a minimum duration of each first phase.

Abstract: Provided is a device comprising a frequency demodulator and an amplitude demodulator. The device is configured to use, in a first mode, both the frequency demodulator and the amplitude demodulator in parallel and to activate a radio frequency identification (RFID) card mode or a Qi charger mode based on results provided by said demodulators.

Abstract: A method for controlling a signal envelope shape of modulation pulses in a driver of a wireless transmitter includes supplying a first voltage to the driver during a non-modulated state, supplying a second voltage configurable by a configurable modulation index value to the driver during a modulated state, switching between the non-modulated state and the modulated state comprising setting the modulation index value to configure the second voltage level at the same level as the first voltage and then switching between supplying the first voltage to the driver and supplying the second voltage to the driver, and filtering to a limited bandwidth the variations of the second voltage resulting from configuring the modulation index value.

Abstract: A method for decoding a data stream carried by a modulated signal includes receiving the modulated signal. The modulated signal is modulated according to a protocol belonging to a group of protocols including at least three protocols. The method further includes extracting a clock signal from the received modulated signal, detecting the protocol, and decoding the data stream according to the detected protocol using the extracted clock signal.

Abstract: A circuit includes an in-phase/quadrature down converter configured to be coupled to an antenna of a first NFC (near field communication) device. DC cancellation circuitry is coupled at outputs of the converter. Detection circuitry is configured to analyze DC signals output by the DC cancellation circuits to detect the presence of a second NFC device.

Abstract: A near field communication (NFC) method includes activating an NFC device second device in response to a first electromagnetic field generated by a nearby NFC device. The NFC device generates a second electromagnetic field after being activated. The first NFC device can detect the second electromagnetic field and initiate a near field communication process.

Abstract: An integrated circuit, includes: an input configured to receive an induced signal that is modulated according to a protocol belonging to the group including protocols using ASK modulation and protocols using OOK modulation; a detection circuit configured to detect the modulation of the induced signal; a decoding circuit configured to detect the protocol; a configurable limiter configured to limit a level of the induced signal and having a first configuration adapted to protocols using ASK modulation and a second configuration adapted to protocols using OOK modulation; and a control circuit configured to set the limiter in the first configuration until a protocol is detected, and to switch the limiter from the first configuration to the second configuration in response to a protocol using OOK modulation being detected.

Abstract: A method for decoding a data stream carried by a modulated signal includes receiving the modulated signal. The modulated signal is modulated according to a protocol belonging to a group of protocols including at least three protocols. The method further includes extracting a clock signal from the received modulated signal, detecting the protocol, and decoding the data stream according to the detected protocol using the extracted clock signal.

Abstract: A transponder communicates with a reader using active load modulation. The transponder includes a digital phase locked loop (DPLL), which, in operation, generates an active load modulation (ALM) carrier clock synchronized to carrier clock of the reader. Between transmission of data frames, the DPLL is placed in a lock mode of operation in which a feedback loop of the DPLL is closed. Within a transmitted data frame having a duration, the DPLL is placed, for the duration of the transmitted data frame, in a hold mode of operation in which the feedback loop is opened. A phase of the ALM carrier clock is adjusted at least once during the duration of the transmitted data frame.

Abstract: A method of wireless communication includes transmitting frames from a transponder to a reader and synchronizing between a reader carrier frequency and an active load modulation (ALM) carrier frequency within each transmitted frame. Each transmitted frame includes ALM carrier bursts generated from subcarrier modulation by binary phase shift keying (BPSK) data encoding and producing signal oscillations at a transponder antenna after each ALM carrier burst generation, The synchronizing occurs at each phase change of the data encoding when no burst is generated during a half period of the subcarrier preceding the phase change and a half period of the subcarrier following this phase change. The transponder antenna has a moderate quality factor sufficient to naturally damp the signal oscillations so that the synchronizing is performed without performing any controlled signal oscillations damping.

Abstract: A transponder communicates with a reader using active load modulation. The transponder includes a digital phase locked loop (DPLL), which, in operation, generates an active load modulation (ALM) carrier clock synchronized to carrier clock of the reader. Between transmission of data frames, the DPLL is placed in a lock mode of operation in which a feedback loop of the DPLL is closed. Within a transmitted data frame having a duration, the DPLL is placed, for the duration of the transmitted data frame, in a hold mode of operation in which the feedback loop is opened. A phase of the ALM carrier clock is adjusted at least once during the duration of the transmitted data frame.

Abstract: In some embodiments, a contactless communication device includes an antenna, and a driving stage having a power supply terminal configured to receive a power supply voltage, where the driving stage is configured to deliver a current to the antenna. The device further includes a monitoring circuit configured to monitor the power transmitted by the antenna. The monitoring circuit is configured, in the presence of a request for a reduction in a current level of transmitted power, to reduce the power supply voltage of the driving stage down to a target value corresponding to a new level of the transmitted power less than the current level.

Abstract: A method of wireless communication includes transmitting frames from a transponder to a reader and synchronizing between a reader carrier frequency and an active load modulation (ALM) carrier frequency within each transmitted frame. Each transmitted frame includes ALM carrier bursts generated from subcarrier modulation by binary phase shift keying (BPSK) data encoding and producing signal oscillations at a transponder antenna after each ALM carrier burst generation, The synchronizing occurs at each phase change of the data encoding when no burst is generated during a half period of the subcarrier preceding the phase change and a half period of the subcarrier following this phase change. The transponder antenna has a moderate quality factor sufficient to naturally damp the signal oscillations so that the synchronizing is performed without performing any controlled signal oscillations damping.