Abstract: A pulse width modulation (PWM) signal generation circuit and method are disclosed herein. The PWM signal generation circuit includes an integer part pulse generation circuit, and a fractional part pulse generation circuit. The integer part pulse generation circuit generates an integer part pulse using the integer part of the digitized value of a duty cycle, i.e., the ratio of the time during which any one of high and low levels is maintained to the period of a PWM signal. The fractional part pulse generation circuit generates the PWM signal using the integer part pulse and the fractional part of the digitized value of the duty cycle.

Abstract: A method for generating a multi-band signal transforms multiple base-band envelope signals into a sequence of symbols representing a signal including a plurality of disjoint frequency bands. Each frequency band corresponds to a single base-band envelope signal. Each symbol corresponds to amplitude of the signal and is a number selected from a finite set of numbers. The method encodes the sequence of symbols as a plurality of pulse width modulation (PWM) signals. Each PWM signal includes a plurality of codes for encoding each symbol, such that a sum of values of the codes of the set of PWM signals encoding a symbol is proportional to a value of the symbol. The method amplifies the PWM signals to produce a plurality of amplified signals and combines the amplified signals to produce the multi-band signal.

Abstract: A multi-phase charging circuit comprises a device that can be configured for master mode operation or slave mode operation. In master mode operation, the device generates a control signal and a clock signal to control operation of a switching circuit for generating charging current. In slave mode operation, the device receives externally generated control and clock signals to control operation of its switching circuit.

Abstract: A memory life extension system and method is provided for managing operation of rewritable memory used to store a monotonically increasing sequence of multiple-byte binary values in a set of one or more memory locations in the rewritable memory. A first value is read in from a set of one or more memory locations. On detection of an instruction to store an incremented value, the incremented value is permuted by applying an encoding, in which a value of a least significant bit changes only on every second increment, to two least significant bits of the incremented value. On overflow of a least significant byte as a result of the increment, a cyclic byte-wise shift is applied to the incremented value. The permuted incremented value is then stored in the one or more memory locations.

Abstract: In one embodiment, a method receives a pulse width modulation signal. A value that is a function of the pulse width modulation signal is determined. The value is used to modulate a switching frequency of the pulse width modulation signal to generate a modulated pulse width modulation signal. The applied value reduces electro-magnetic interference from tones in the modulated pulse width modulation signal.

Abstract: Analog-to-digital pulse width modulation circuitry includes thermometer code generator circuitry, clock generator circuitry, delay selection circuitry, and an output stage. The thermometer code generator circuitry is adapted to generate a digital thermometer code based upon a received analog input voltage. The clock generator circuitry is adapted to generate a reference clock and a plurality of delayed clock signals. The delay selection circuitry is connected between the thermometer code generator circuitry and the clock generator circuitry, and is adapted to select one of the delayed clock signals to present to the output stage based upon the generated thermometer code. The selected delayed clock signal is delayed by an amount of time that is proportional to the generated thermometer code. The reference clock signal and the selected delayed clock signal are delivered to the output stage where they are used to generate a pulse width modulated output signal.

Abstract: Determining the rotor angle of a synchronous machine. In one aspect, the invention provides a method that includes generating a multiplicity of pulse-width-modulated drive signals for the phases of an inverter feeding the synchronous machine depending on a voltage to be fed into the synchronous machine, and applying a first phase shift to one or more of the multiplicity of pulse-width-modulated drive signals, so that the duration of the switching states of the inverter is extended in order to generate a first switching pattern for the phases of the inverter. The method also includes applying a second phase shift to one or more of the multiplicity of pulse-width-modulated drive signals for generating a second switching pattern, selecting one or more of the first and second switching patterns, determining one or more of neutral point potentials at the neutral point of the synchronous machine, and calculating the rotor angle of the synchronous machine.

Abstract: A digital event generator includes a counter configured to provide at least one count value based on a clock signal, and a comparator configured to evaluate a first portion of a first count value to detect a near occurrence of an event, in response to a detection of a near occurrence of an event, evaluate a second portion of a second count value, and provide the event signal based on the evaluation and digital event time information. A switched mode energy converter uses said digital event generator.

Abstract: A communication unit comprises a power DAC. The DAC comprises: a switched mode power amplifier (SMPA); and a digital band-pass sigma-delta modulator operably coupled to the SMPA. The sigma-delta modulator comprises an input to receive an input baseband signal; a delay; an adder module arranged to add a feedback signal with an output from the delay; and at least two feedback branches. The sigma-delta modulator is arranged to digitally oversample the input baseband signal such that a ratio of a sampling frequency employed by the sigma-delta modulator to a radio frequency (RF) output from the DAC is fixed and the sampling frequency tuned or wherein the sampling frequency is fixed and the ratio is adjusted, such that a first feedback branch in the sigma-delta modulator is formed using at least one from a group of: a zero gain, an additive inverse of a second feedback branch.

Abstract: Method for communication between an electronic module and a sensor having a light source and being supplied by supply line, the electronic module measuring the modulations of the intensity of the current in the line. The sensor drives a gradual turning on/turning off of the light source by a first modulation of the intensity of the current such that: the light source is turned off, respectively turned on, when the intensity of the current is in a low, respectively high, state, and the light source illuminates, respectively turns off, when the duty ratio of the intensity of the current varies from the high state to the low state and vice versa. During detection, the sensor dispatches a second modulation through the light source, however if the light source is turning on (or off), this is interrupted and the intensity of current is forced to the high (or low) state.

Abstract: A decoder for decoding an input signal coded with a pulse width modulation code as a line code to an output signal in a binary code, has a first memory, a first timer, a determination circuit and a first controller. The information on a duty duration of the PWM code, corresponding to at least one kind of the output signals, is stored on the first memory. The first timer has a capacity to measure the duty duration of the input signal. The determination circuit has a capacity to determining which kind of the output signals corresponds to the input signal, on the basis of the information stored on the first memory and the duty duration measured with the first timer. The first controller has a capacity to updating the information stored on the first memory, on the basis of the determination result and the measured duty duration.

Abstract: Described herein are an apparatus, system, and method for generating pulse modulated (PWM) signals. The apparatus (e.g., input-output transmitter) comprises: an edge detector to detect one of a rising or falling edges of a clock signal; a counter to count up or down in response to detecting one of the rising or falling edges of the clock signal, the counter to generate a select signal; and a control unit to receive a data signal for transmission to a receiver and to generate a PWM signal as output according to a value of the select signal and the data signal, wherein the receiver and the transmitter are a Mobile Industry Processor Interface (MIPI®) M-PHYSM receiver and transmitter.

Abstract: A digitally controlled non-inverting buck-boost DC-DC converter system including a non-inverting buck-boost DC-to-DC converter control module and a negative feedback module and applicable for a radio frequency circuit module is revealed. By locking a duty cycle to two specific levels, the non-inverting buck-boost DC-to-DC converter control module only needs a single operation mode to achieve the required effects. Simultaneously, pulse-skipping phenomenon is also avoided. Furthermore, a reference voltage is modified through a reference voltage correction circuit of the negative feedback module to eliminate errors between previous DC output voltage and the reference voltage. Thereby the DC output voltage can remain in a stable state so as to reduce operational defects during the mode transition.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for transmitting data. In one aspect, a method obtains a baseline data rate for transmissions from a node that are received over a channel of a power line communications system and a set of available modulation techniques for the node. The set of available modulation techniques can include at least two modulation techniques with which the node is configured to encode data that are transmitted over the channel. Using the set of available modulation techniques, a modulation technique that is capable of providing at least the baseline data rate with at least a threshold confidence for the node is selected. In turn, data is provided to the node specifying the selected modulation technique.

Abstract: Systems, methods, and other embodiments associated with estimating a natural sampling point from uniform sample points when generating a PWM signal are described. According to one embodiment, an apparatus includes a cross point logic configured to determine which of the samples along the analog signal are adjacent to a crossing point of a reference signal and the analog signal by identifying samples between which the crossing point occurs. The apparatus includes an interpolation logic configured to adaptively interpolate points along the analog signal that approach the crossing point by using the samples. The interpolation logic is configured to adaptively interpolate the points to refine a region between the points within which the crossing point occurs. The apparatus includes a search logic configured to search within the region to produce an estimated location of the crossing point by using the interpolated points.

Abstract: A power amplifier (PA) which improves dynamic range of previous ZVS contour-based power amplifier architectures is presented. The inventive circuit combines ZVS contour-based power amplification with a current mode digital-to-analog converter (DAC) based digital polar power amplifier. The inventive elements interoperate to provide high efficiency even at large peak power back-off levels and increased dynamic range. The invention is particularly well-suited for use in modulation schemes (e.g., WLAN/LTE/WIMAX) having large peak-to-average output power ratios. Utilizing the inventive PA in generating modulation in these systems can increase RF transmitter efficiency of by approximately two-fold.

Abstract: Various embodiments of the present invention relate to AC-DC adapters, and more particularly, to systems, devices and methods of employing a load detector to detect a load condition of the AC-DC adapters based on transient variation of a DC output voltage; and therefore, enable the AC-DC adapters to switch from a low power mode to a normal power mode. At the low power mode, a DC output voltage is generated at a target voltage by the AC-DC adapter, and subsequently drops at a decay rate dependent on load condition. The load detector is electrically coupled to monitor the output voltage and measure the decay time between two threshold voltages. An enable instruction is provided to configure the AC-DC adapter to the normal power mode as soon as the decay time is lower than the threshold decay time or the variation of consecutive decay times reaches a certain threshold.

Abstract: A transmitter includes a first digital up-converter for converting data to an intermediate frequency (IF) signal, a pulse width modulator (PWM) for encoding the IF signal to an IF pulse train, a second digital up-converter for converting the IF pulse train to a radio frequency (RF) pulse train, a power amplifier for amplifying the RF pulse train; and a filter for reconstructing a RF analog signal from the amplified RF pulse train.

Abstract: A data receiver has a reception circuit and a fail-safe circuit. The reception circuit has an input amplifier, a logic signal processing circuit, and a reception stop control circuit. The fail-safe circuit has a high-pass filter, a comparator, and a pulse width extending circuit. The reception circuit receives a serial data of differential input signals based on a predetermined standard, converts the serial data into a serial data of a single-ended output signal, and outputs a converted serial data. The fail-safe circuit detects whether the differential input signals have a nonstandard small amplitude and outputs a fail-safe detection signal indicating a detection result.

Abstract: A PWM signal generating circuit, printer, and PWM signal generating method are described. The PWM signal generating circuit includes: a single counter configured to count values expressed in N bits; and at least one arithmetic device configured to generate a PWM signal, each of the at least one arithmetic device including a pulse width data storage unit for storing N-bit pulse width data representing a pulse width of the PWM signal to be generated, and an adder for calculating a carry value from a most significant bit obtained when adding the count value and the pulse width data. A signal having a level corresponding to the carry value is output at every change in the count value so that the PWM signal having the pulse width of the pulse width data is generated.

Abstract: An RF signal generating circuit that generates, from a digital signal, an RF pulse signal to be radio-transmitted. It includes a polar converter generating an amplitude signal and a phase signal from the digital signal; a signal decomposer receiving the amplitude signal as an input signal, and generates two signals, a pulse width control signal and a residual signal; a delta sigma modulator subjecting the residual signal to delta-sigma modulation; a pulse width modulator subjecting the phase signal to pulse modulation in accordance with the pulse width control signal, and outputting a pulse phase signal; and a mixer that mixes a signal output from the delta sigma modulator and the pulse phase signal to output the RF pulse signal. The signal decomposer generates the pulse width control and residual signals if a product of a fundamental wave component of the pulse phase and residual signals equals the amplitude signal.

Abstract: A power encoder includes an amplitude-phase splitter for splitting an input signal into an envelope signal and a phase modulated signal, and a pre-distortion unit for distorting the envelope signal using a look-up table (LUT) to produce a distorted envelope signal. The power encoder also includes a digital converter for combining the distorted envelope signal with the phase modulated signal to produce a distorted input signal, a pulse width modulator (PWM) for modulating the distorted input signal according to the transformation function to produce a modulated signal, and a switch mode power amplifier for amplifying the modulated signal. The look-up table stores a non-linear mapping of a transformation function and a relationship between the distorted input signal and the modulated signal is non-linear.

Abstract: An integrated circuit includes: a digitally-controlled power generation stage for converting an input signal to a radio frequency (RF) carrier, the digitally-controlled power generation stage including a plurality of selectable switching devices capable of adjusting an envelope of the RF carrier; and a pulse width modulator (PWM) generator arranged to generate a PWM control signal according to a fractional word and operably coupleable to the plurality of selectable switching devices of the digitally-controlled power generation stage; wherein the PWM generator inputs the PWM control signal to a subset of the plurality of the selectable switching devices such that a PWM signal adjusts the envelope of the RF carrier output from the digitally-controlled power generation stage.

Abstract: In one embodiment, a method receives a pulse width modulation signal. A value that is a function of the pulse width modulation signal is determined. The value is used to modulate a switching frequency of the pulse width modulation signal to generate a modulated pulse width modulation signal. The applied value reduces electro-magnetic interference from tones in the modulated pulse width modulation signal.

Abstract: A power transmitting apparatus is usable for wireless power and data transmission. The power transmitting apparatus includes a power transmitting section configured to transmit power and data to be transmitted as being converted into a pulse train; and a control section configured to control the power transmitting section such that a change of the power caused by superimposition of the data is decreased.

Abstract: A power transmitter 50 is usable in a wireless power transmission system for transmitting power wirelessly. The power transmitter 50 includes a power transmitting section 51 for transmitting power; a communication section 52 for communicating information, for controlling the transmission of the power, with the power receiver 60; and a control section 53 for controlling the power transmitting section 51 such that the power to be sent out by the power transmitting section 51 is higher while the communication section 52 is performing the communication.

Abstract: In various embodiments, systems and methods for generating high-precision pulse-width modulation include a delay-locked loop comprising multiple delay units having time-variable delays, control logic for selecting a subset S of the multiple delay units to thereby generate a time-invariant shift amount having a precision finer than that of a system clock and circuitry for applying the shift amount to rising and falling edges of a pulse-width modulation waveform to thereby generate a high-precision pulse-width modulation waveform.

Abstract: A system and method involve transceiving successive first and second synchronization signals defining endpoints of a frame. A digital signal is transceived by a modulating time interval between portions of the first and second synchronization signals. A first data pulse is transceived during the frame. A relative position in the frame of the first data pulse represents a first analog signal.

Abstract: An apparatus comprises a number of sub-systems and a control interface operably coupled to sub-systems for routing data therebetween. A strobe generation function is operably coupled to the control interface and configured to generate a plurality of different strobe signals to differentiate between different intended receiving devices. Thus, different strobe signals may be multiplexed onto a single control interface link, based on a pulse width or voltage magnitude characteristics of the respective strobe signals. A strobe decoder function is operably coupled to the control interface and configured to decode a plurality of different strobe signals to differentiate between triggering sub-systems on receiving devices.

Abstract: A QAM transmitter is disclosed that may reduce the frequency of local clock signals and/or reduce the switching frequency of driver circuits when generating a QAM output signal for transmission. The QAM transmitter may generate a number of PWM signals indicative of in-phase (I) and quadrature (Q) signal components, and then use one or more selected even-order harmonics of the PWM signals to generate the QAM output signal. Odd-order harmonics of the PWM signals may be suppressed by selectively combining the PWM signals, and any remaining unwanted even-order harmonics may be suppressed using filters.

Abstract: An analog signal is transported across an isolation channel using edge modulation/demodulation of a pulse width modulated (PWM) signal. An edge modulator is responsive to rising edges of the PWM signal to generate first pulses having a first predetermined pulse width and is responsive to receipt of falling edges of the PWM signal to generate second pulses having a second predetermined pulse width with the same polarity as the first pulses. On the opposite side of the isolation channel an edge demodulating circuit recreates the PWM signal using the first and second pulses. The rise and falling edges of the PWM signals can be distinguished based on the pulse width of the first and second pulses. A second order pulse width modulator may be used to generate the PWM signal.

Abstract: A method is provided for generating a digital signal (DS) from an analog signal (IA, UA) generated by a frequency converter on the basis of pulse width modulation, wherein the digital signal corresponds to a mean value of the analog signal over a period of the pulse width modulation. The method includes the acts of: generating a bit stream (BS(i)) with a predetermined bit repetition duration (BW) depending on the analog signal by way of a sigma-delta modulator (1) and, during a time interval which has a duration which is at least as great as the period of the pulse width modulation: multiplying a respective bit (BS(i)) of the bit stream by a corresponding rating coefficient (BK(i)) for generating a respective bit/rating coefficient product and summing the respective bit/rating coefficient products, wherein the sum represents the digital signal.

Abstract: In an embodiment, a method of producing a multi-level RF signal includes producing plurality of pulse-width modulated signals based on an input signal. The method further includes driving a corresponding plurality of parallel amplifiers with the plurality of pulse-width modulated signals by setting a parallel amplifier to have a first output impedance when a corresponding pulse-width modulated signal is in an active state and setting the parallel amplifier to have a second output impedance when the corresponding pulse-width is in an inactive state. The method also includes phase shifting the outputs of the plurality of parallel amplifiers, wherein phase shifting transforms the second output impedance into a third impedance that is higher than the second output impedance, and combining the phase shifted outputs.

Abstract: An apparatus for transmitting a high efficiency variable power includes a pulse generating unit configured to generate a pulse signal comprising a pulse having a duration corresponding to an amount of power transmitted; a pulse stream generating unit configured to convert the pulse signal to a pulse stream having pulse shape corresponding to the duration of the pulse and data to be transmitted; and a high frequency modulating unit configured to output a variable power by modulating a high frequency signal having a constant amplitude on a time axis by repeatedly outputting and not outputting the high frequency signal based on the pulse stream.

Abstract: The present invention provides a digital receiver configured to demodulate or decode a pulse-width modulated (PWM) signal from a transmitter. The receiver digitally demodulates or decodes the pulse-width modulated signal so as to obtain (binary) values of data modulated on pulse periods of the pulse-width modulated signal. The digital receiver includes multiple delay cells coupled to one another in series and a sampling circuit coupled to one of the delay cells. A sequential coupling of the delay cells composes a signal path, and each of the delay cells is designed to provide a corresponding delay to a corresponding input signal propagating along the signal path so as to generate a delayed signal as its output.

Abstract: A communication system performs communication using a pulse width modulation code as a transmission code. The communication system includes a plurality of nodes that are connected via a transmission line to be capable of communicating with each other. Each of the nodes including a driver circuit. The driver circuit includes a transistor that enables and blocks conduction between the transmission line and a ground line. The plurality of nodes includes a master node and a slave node. The master node is one of the plurality of nodes. The slave node is at least one node other than the master node among the plurality of nodes. The master node includes a limiter that restricts, when the transistor of the driver circuit is turned off, changes in a conductive state of the transistor.

Abstract: A digital pulse width generator and a method for generating a digital pulse width are provided. The method for generating a digital pulse width includes the following. Generating a first period according to first set of bits of pulse data. The first period includes an interval. First phase signals are set to a first logic value in the interval and are generated according to first phase clock signals after an end of the interval. Second phase signals are set to the first logic value in the first period and are generated according to second phase clock signals after an end of the first period. Selecting a first signal from the first phase signals and the second phase signals according to second set of bits of the pulse data as a pulse width signal.

Abstract: A transmitter includes a first digital up-converter for converting data to an intermediate frequency (IF) signal, a pulse width modulator (PWM) for encoding the IF signal to an IF pulse train, a second digital up-converter for converting the IF pulse train to a radio frequency (RF) pulse train, a power amplifier for amplifying the RF pulse train; and a filter for reconstructing a RF analog signal from the amplified RF pulse train.

Abstract: Serial data are transmitted between transceivers via a communication path, each bit expressed by a dominant code or a recessive code which vary between dominant and recessive levels, the dominant code having a greater proportion of duration at the dominant level. A device (clock master) can continuously output successive recessive codes to the communication path, in which condition a transceiver can transmit a dominant code by producing an output drive signal which overwrites a part of a recessive code, currently being received from the communication path, to the dominant level. The output drive signal is shaped with a steeper edge slope at a transition from an inactive to an active level than from the active to the inactive level, enabling an increased data transmission rate without increased noise.

Abstract: A sampling device for sampling an incoming signal in order to generate an output signal having a different frequency spectrum from the incoming signal. The device comprises a sampler configured to sample the incoming signal at a series of intervals in time, wherein the series of intervals includes a temporally repeating sequence of intervals, and wherein the duration of successive intervals varies throughout the series.

Abstract: In one embodiment, a method receives a pulse width modulation signal. A value that is a function of the pulse width modulation signal is determined. The value is used to modulate a switching frequency of the pulse width modulation signal to generate a modulated pulse width modulation signal. The applied value reduces electro-magnetic interference from tones in the modulated pulse width modulation signal.

Abstract: An NFC transmitter using a delay-locked loop and an NFC transmission method thereof are provided. The NFC near field communication (NFC) transmitter includes a delay-locked loop (DLL) that outputs a reference clock and a delayed clock using the reference clock and a value of a duty code which are input, a clock output unit that receives the reference clock and the delayed clock, outputs the reference clock in any of a high section and a low section of input data, and outputs a converted clock having a duty ratio using the reference clock and the delayed clock in the other of the high section and the lower section of the input data, and an RF signal generator that generates an RF signal using a PWM (Pulse Width Modulation) signal input from the clock output unit.

Abstract: A receiver for decoding a communication signal is disclosed. The receiver includes an input port and a filter. The input port receives the communication signal from a communication medium. The communication signal comprises a sequence of symbols. Each symbol of the symbol sequence is an analog pulse that has a leading edge of exponential shape. The exponential shape has an exponential growth parameter value that has been selected from values ?0 and ?1, which are distinct positive values. For each symbol of the symbol sequence, the exponential growth parameter value for the leading edge of the symbol has been selected based on a corresponding bit from a stream of information bits. The filter receives the communication signal from the input port and filters the communication signal to obtain an output signal. The transfer function of the filter has one or more zeros at ?0.

Abstract: A clock data recovery circuit includes a ring oscillator, an oscillation control circuit unit to start or stop the ring oscillator according to existence or absence of a PWM signal, a counter circuit unit to count pulse signals to hold N bits of count value, a register circuit unit which is configured to transmit upper M bits of count value, as a reference count value, in response to a transmission signal, a comparison circuit unit to output a timing clock when the count value exceeds the reference count value, and a transmission control circuit unit to be synchronized with a rising timing of the PWM signal to generate the transmission signal and a reset signal for resetting the counter circuit unit.

Abstract: In one embodiment, an apparatus including a phase detector unit to determine a phase difference between an inverted reference clock signal and a feedback clock signal. The apparatus further includes a controller unit to generate a delay signal based on the phase difference. The apparatus further includes a set of voltage-controlled delay lines to generate phase outputs based on the delay signal, where the phase outputs are provided by the apparatus to a clock generator unit to generate an oversampled clock signal for data recovery by a receiver.

Abstract: A device and a method for pulse width modulation is disclosed, wherein the temporal occurrence of both the respectively rising and the respectively falling edges of a pulse signal is varied.

Abstract: A PWM circuit that can have two refresh rates, including: a first PWM signal generator and a second PWM signal generator; wherein the first PWM signal generator and the second PWM signal generator respectively control refresh rates in two dimensions of an output data generated from a target apparatus. A PWM signal generation method that can have two refresh rates, including: generating a first PWM signal; generating a second PWM signal; and controlling refresh rates in different dimensions of an output data generated from a target apparatus respectively by using the first PWM signal and the second PWM signal.

Abstract: A torque measurement system that includes a rotor device and a stator device can perform automatic tuning to improve the initial tuning performed during design and assembly. The stator device can include a variable capacitive element and a micro-controller configured to adjust a capacitance value of the variable capacitive element. Additionally or alternatively, the rotor device can include a variable capacitive element and a micro-controller configured to adjust a capacitance value of the variable capacitive element. The adjustment of the capacitive elements can be based on the quality of signal detected at either the rotor device or stator device.

Abstract: A method of generating spurious-noise-free power from a switching device. The method includes generating an oscillating signal in the form of a series of pulse trains, and randomly changing the switching frequency, or the on-time, or both the switching frequency and the on-time of the switching device. The method further includes causing the switching device to change from a first frequency to a second frequency only at the end of a pulse train of the first frequency, and causing the second frequency to start at the beginning of its first pulse train such that no switching duty-cycle disturbance at the time of the change from first to second frequency. In a particular embodiment, the method further generates spurious-noise-free power from a switching device by implementing a relationship between the different switching frequencies involved such that spurious-noise-free operation is achieved.

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.