Abstract: A method for inductively coupled communication is described. The method includes generating a first signal. The first signal frequency is a first integer multiple of a carrier frequency for inductively coupled communication. The method also includes selecting between a standalone mode and a coexistence mode. The method further includes dividing the first signal to obtain a second signal when in standalone mode. The second signal frequency is a second integer multiple of the carrier frequency. The method additionally includes dividing the first signal to obtain a third signal when in coexistence mode. The third signal frequency is a third integer multiple of the carrier frequency. The method also includes generating an inductively coupled communication signal using at least one of the second signal and the third signal.

Abstract: A method for inductively coupled communication is described. The method includes transmitting a carrier signal from a first device while receiving the carrier signal at a receiver of the first device. The method also includes determining a carrier level estimation using a loopback path on the receiver of the first device. The method further includes controlling a transmit power level of the first device based on a coupling strength with a second device as indicated by the carrier level estimation.

Abstract: A method for inductively coupled communications is described. The method includes generating a retransmitted modulated signal that is stronger than a received signal from a first device. The method also includes generating a suppressed carrier signal from the retransmitted modulated signal for retransmission to the first device. The method further includes filtering a superimposed signal of the suppressed carrier signal on the received signal to attenuate modulation sidebands. The method additionally includes synchronizing to the first device based on the filtered signal.

Abstract: A method for inductively coupled communication is described. The method includes transmitting a carrier signal from a first device while receiving the carrier signal at a receiver of the first device. The method also includes determining a carrier level estimation using a loopback path on the receiver of the first device. The method further includes controlling a transmit power level of the first device based on a coupling strength with a second device as indicated by the carrier level estimation.

Abstract: A method for inductively coupled communication is described. The method includes generating a first signal. The first signal frequency is a first integer multiple of a carrier frequency for inductively coupled communication. The method also includes selecting between a standalone mode and a coexistence mode. The method further includes dividing the first signal to obtain a second signal when in standalone mode. The second signal frequency is a second integer multiple of the carrier frequency. The method additionally includes dividing the first signal to obtain a third signal when in coexistence mode. The third signal frequency is a third integer multiple of the carrier frequency. The method also includes generating an inductively coupled communication signal using at least one of the second signal and the third signal.

Abstract: A method for inductively coupled communications is described. The method includes generating a retransmitted modulated signal that is stronger than a received signal from a first device. The method also includes generating a suppressed carrier signal from the retransmitted modulated signal for retransmission to the first device. The method further includes filtering a superimposed signal of the suppressed carrier signal on the received signal to attenuate modulation sidebands. The method additionally includes synchronizing to the first device based on the filtered signal.

Abstract: A near-field communications (NFC) device includes an NFC antenna, a matching network coupled to the NFC antenna, and a transmitter coupled to the matching network. The transmitter applies a signal to the matching network and varies a frequency of the signal. A parameter is measured while varying the frequency of the signal. A peak value of the parameter is identified and compared to a threshold. A communication protocol is initiated in response to a determination that the peak value satisfies the threshold.

Abstract: First and second NFC devices both seek to determine whether the other device is present and available for communication across an NFC channel. The first NFC device modulates a load in its transceiver. The second NFC device transmits a waveform. If the first NFC device detects the waveform while modulating its load, and if the second NFC device detects the load modulation while transmitting the waveform, then the two NFC devices initiate communication in accordance with a communication protocol.

Abstract: A near-field communications (NFC) device includes an NFC antenna, a matching network coupled to the NFC antenna, and a transmitter coupled to the matching network. The transmitter applies a signal to the matching network and a capacitance of the matching network is varied. A parameter is measured while varying the capacitance of the matching network and while applying the signal. A peak value of the parameter is identified and compared to a threshold. A communication protocol is initiated in response to a determination that the peak value satisfies the threshold.

Abstract: The present systems and methods may shape signals to meet emission mask requirements, current consumption requirements, and overshoot/undershoot requirements relating to the interaction that, for example, occurs when a near field communications (NFC) target comes within range of an NFC initiator, and the initiator generates and transmits an NFC waveform. In some implementations, a pair of bit patterns are defined whose differential output from an amplifier is a shaped pulse width modulated waveform. Varying individual bits of the bit patterns can vary the shaped pulse waveform with predictability. The pulse width modulated waveform may be filtered using a matching network that reduces higher order harmonics, thereby reducing out-of-band emissions.

Abstract: A multipath circuit is described that has multiple signal paths and various common components used for normal operation. Each of the multiple signal paths also has multiple circuit blocks defining the functionality of the signal path. A shared access path is provided through the third winding of a three-way transformer for each signal path. Multiple switches are provided in the multipath circuit that couple to the third winding in each of the multiple signal paths. The switches are also coupled to the various common components. Selected ones of these switches may be closed to provide a shared access path between a common component and one of the signal paths or between a common components and one of the circuit blocks in one of the signal paths.

Abstract: First and second NFC devices both seek to determine whether the other device is present and available for communication across an NFC channel. The first NFC device modulates a load in its transceiver. The second NFC device transmits a waveform. If the first NFC device detects the waveform while modulating its load, and if the second NFC device detects the load modulation while transmitting the waveform, then the two NFC devices initiate communication in accordance with a communication protocol.

Abstract: A near-field communications (NFC) device includes an NFC antenna, a matching network coupled to the NFC antenna, and a transmitter coupled to the matching network. The transmitter applies a signal to the matching network and varies a frequency of the signal. A parameter is measured while varying the frequency of the signal. A peak value of the parameter is identified and compared to a threshold. A communication protocol is initiated in response to a determination that the peak value satisfies the threshold.

Abstract: A near-field communications (NFC) device includes an NFC antenna, a matching network coupled to the NFC antenna, and a transmitter coupled to the matching network. The transmitter applies a signal to the matching network and a capacitance of the matching network is varied. A parameter is measured while varying the capacitance of the matching network and while applying the signal. A peak value of the parameter is identified and compared to a threshold. A communication protocol is initiated in response to a determination that the peak value satisfies the threshold.

Abstract: Systems and methods are disclosed that can shape signals to meet emission mask requirements, current consumption requirements, and overshoot/undershoot requirements relating to the interaction that, for example, occurs when a near field communications (NFC) target comes within range of an NFC initiator, and the initiator generates and transmits an NFC waveform. In some implementations, a pair of bit patterns are defined whose differential output from an amplifier is a shaped pulse width modulated waveform. Varying individual bits of the bit patterns can vary the shaped pulse waveform with predictability. The pulse width modulated waveform may be filtered using a matching network that reduces higher order harmonics, thereby reducing out-of-band emissions.

Abstract: A multipath circuit is described that has multiple signal paths and various common components used for normal operation. Each of the multiple signal paths also has multiple circuit blocks defining the functionality of the signal path. A shared access path is provided through the third winding of a three-way transformer for each signal path. Multiple switches are provided in the multipath circuit that couple to the third winding in each of the multiple signal paths. The switches are also coupled to the various common components. Selected ones of these switches may be closed to provide a shared access path between a common component and one of the signal paths or between a common components and one of the circuit blocks in one of the signal paths.

Abstract: Techniques for low-pass filtering with high quality factor (Q). In an exemplary embodiment, an input current is coupled to the drain of a first transistor. The drain and the gate of the first transistor are coupled together by a resistor R1, and the drain is coupled to a reference voltage by a first capacitor C1. The gate is coupled to a reference voltage by a second capacitor C2. The gate is further coupled to the gate of a second transistor, and an output current is coupled to the drain of the second transistor. In another exemplary embodiment, further passive elements may be coupled to generate an odd-order low-pass transfer characteristic. Multiple filters may be cascaded in series to synthesize a filter having arbitrary order.

Abstract: Systems and methodologies are described that facilitate calibration techniques for a station in a wireless communication system that can be utilized to provide joint estimates for distortion introduced by in-phase and quadrature (I/Q) imbalance and mixing-product modulated images.

Abstract: Techniques for low-pass filtering with high quality factor (Q). In an exemplary embodiment, an input current is coupled to the drain of a first transistor. The drain and the gate of the first transistor are coupled together by a resistor R1, and the drain is coupled to a reference voltage by a first capacitor C1. The gate is coupled to a reference voltage by a second capacitor C2. The gate is further coupled to the gate of a second transistor, and an output current is coupled to the drain of the second transistor. In another exemplary embodiment, further passive elements may be coupled to generate an odd-order low-pass transfer characteristic. Multiple filters may be cascaded in series to synthesize a filter having arbitrary order.

Abstract: Systems and methodologies are described that facilitate calibration techniques for a station in a wireless communication system that can be utilized to provide joint estimates for distortion introduced by in-phase and quadrature (I/Q) imbalance and mixing-product modulated images.