In one aspect, an apparatus for drilling a wellbore into an earth formation is disclosed, which apparatus, according to one embodiment, may include a drill string configured to be conveyed into a wellbore, wherein an annulus is formed between the drill string and a wellbore wall, a first flow device configured to circulate a first fluid from an annulus to a bore of the drill string, and a second flow device positioned downhole of the first flow device, the second flow device configured to circulate a second fluid from the bore of the drill string to the annulus.

Diamond bonded constructions comprise a diamond body attached to a substrate, wherein the body includes a first diamond bonded volume, and a second diamond bonded volume attached thereto. The second volume may be provided in the form of a powder or a presintered mass prior to attachment, and the first volume may be provided in the form of presintered pieces when combined with the second volume. The first volume diamond volume content is greater than about 94 percent, and is the same or greater than that of the second volume. The first volume is sintered during a first HPHT process, and the second volume is sintered and/or attached to the first volume during a second HPHT process. The first HPHT pressure is greater than the second HPHT pressure. The substrate is not an infiltration substrate used to form the first diamond volume. The diamond body may be thermally stable.

An arrangement having a piston configured to move along an axial pathway a rotating seal configured to seal an inside environment from an outside environment, the rotating seal configured to be acted upon by a pressure exerted from the piston, a differential pressure sensor measuring a pressure difference between a first fluid from the outside environment and a second fluid on the inside environment, a motor connected to the piston, the motor configured to actuate the piston to a position along an axial pathway and an electronic feedback control system connected to the motor, the electronic feedback system configured to interface with the differential pressure sensor and maintain a pressure generated by the piston onto the rotating seal to a desired pressure.

In at least some embodiments, a pulsed-electric drilling system includes a bit that extends a borehole by detaching formation material with pulses of electric current, and a drillstring that defines at least one path for a fluid flow to the bit to flush detached formation material from the borehole. A feed pipe transports at least a part of said fluid flow to said path, and the feed pipe is equipped with a cooling mechanism to cool the fluid flow. The use of a cooled fluid flow may enhance the performance of the pulsed-electric drilling process.

There is provided a cassette having: a flexible accommodating body that accommodates an accumulative fluorescent sheet in a light shielded state; an entrance/exit portion that is provided at one end portion of the flexible accommodating body, and through which the accumulative fluorescent sheet can be inserted and removed into and from the flexible accommodating body due to mounting to a radiographic image reading device; and opening/closing means for opening the flexible accommodating body such that a push-out member, that pushes the accumulative fluorescent sheet out toward the entrance/exit portion, can be inserted, or closing the flexible accommodating body in a light shielded state.

A chamber used in an extreme ultraviolet light generation apparatus that generates extreme ultraviolet light by irradiating a target material with a laser beam may include a chamber receptacle, a heat shield that is disposed within the chamber receptacle between a predetermined region where the target material turns into plasma and the chamber receptacle and that is configured to absorb heat produced at the predetermined region when the target material turns into plasma, and a support portion configured to attach the heat shield to the chamber receptacle, and further, the support portion may include an absorbing portion configured to absorb stress produced in the heat shield deforming due to the heat, by expanding/contracting in response to the thermal deformation of the heat shield.

An approach is disclosed for acquiring multi-sector computed tomography scan data. The approach includes activating an X-ray source during heartbeats of a patient to acquire projection data over a limited angular range for each heartbeat. The projection data acquired over the different is combined. An image having good temporal resolution is reconstructed using the combined projection data.

The invention relates to a device (10; 10a;10b; 10c; 50) for checking pharmaceutical products (1), in particular hard gelatin capsules, by means of at least one radiation source (30; 60) preferably embodied as an X-ray source, and a conveying device which conveys the products (1) in a clocked manner in a radiation area (31) of the radiation source (30; 60). The radiation emitted by the radiation source (30; 60) penetrating the products (1) preferably perpendicular to the longitudinal axes thereof (2), and the radiation is captured on the side of the products (1) opposite the radiation source (30) by means of at least one sensor element (35) which is coupled to an evaluation device (36). The invention is characterized in that the conveyor device is embodied as a conveyor wheel (15; 15a; 51) which can rotate in a stepped manner about an axis (12; 52), and the products (1) are arranged, while being conveyed in the radiation area (31), in receiving areas (28; 37; 56) of the conveyor wheel (15; 5a; 51).

An apparatus comprises a plasma flood gun for neutralizing a positive charge buildup on a semiconductor wafer during a process of ion implantation using an ion beam. The plasma flood gun comprises more than two arc chambers, wherein each arc chamber is configured to generate and release electrons into the ion beam in a respective zone adjacent to the semiconductor wafer.

In one aspect, an optical device comprises a monolithic optical module which includes a first total internal reflection (TIR) surface, a second TIR surface adjacent the first TIR surface, and a first optical port aligned with the first internal optical beam dividing interface. An interface between the first TIR surface and the second TIR surface forms a first internal optical beam dividing interface. An exterior surface of the first TIR surface and an exterior surface of the second TIR surface form a generally V-shaped notch on the monolithic optical module. A first optical beam entering the monolithic optical module through the first optical port and incident on the first internal optical beam dividing interface is partially reflected by the first TIR surface to travel in a first direction as a second optical beam and partially reflected by the second TIR surface to travel in a second direction as a third optical beam. The second direction is generally opposite to the first direction.

The present invention is directed to additives for coal-fired furnaces, particularly furnaces using a layer of slag to capture coal particles for combustion. The additive(s) include iron, mineralizer(s), handling aid(s), flow aid(s), and/or abrasive material(s). The iron and mineralizers can lower the melting temperature of ash in low-iron, high alkali coals, leading to improved furnace performance.

A pulverized coal burner and a pulverized coal boiler. The coal burner comprises a primary air cylinder (111) and a pulverized coal concentration device (112). The coal concentration device (112) makes the concentration of the coal flow gradually decrease from inside to outside along the radial direction, with respect to an axis (100) of the primary air cylinder (111). The coal burner further comprises a coal separating cylinder (113) and a coal guiding cylinder (114) located downstream of the device (112), the rear end of the cylinder (113) is connected with the front end of the coal guiding cylinder (114). The outlet of the cylinder (114) has a conical expansion portion (1141). The coal burner further comprises a divergent nozzle (115) connected with the rear end of the primary air cylinder (111) and whose cross-sectional area gradually increases along the flow direction of the coal flow.

An apparatus for processing fly ash comprising a heated refractory-lined vessel having a series of spaced angled rows of swirl-inducing nozzles which cause cyclonic and/or turbulent air flow of the fly ash when introduced in the vessel, thus increasing the residence time of airborne particles. Also disclosed is a method of fly ash beneficiation using the apparatus.

A method is illustrated and described for reducing unwanted substances by injecting a reactant into a flue gas of a steam generator. In order that the reactant can also be used in larger steam generators and/or combustion chambers, a method is proposed, in which the reactant is injected into the combustion chamber of the steam generator via a reactant opening of a multi-component nozzle, in which an enveloping medium is injected into the combustion chamber through at least one enveloping medium opening arranged outside the reactant opening, and in which the enveloping medium at least partly envelops the reactant in the combustion chamber and in this way at least partly shields the reactant from the flue gas.

A combustion device in the form of an elevated fixed-grate that includes arcuately shaped solid refractory brick with ribs placed thereunder so as to allow horizontal air flow for fuel combustion. The brick are arranged atop one another in a stacked concentric configuration that forms a central fuel passageway and allows cascading of a fuel pile throughout the combustion stages. The device provides the benefit of proper de-ashing online while distributing the underfire air radially around the fuel pile. The elevated design of the bricks allows the air to be evenly distributed throughout the fuel pile and further allows the isolation of overfire and underfire air. Segregating overfire and underfire air in an evenly distributed manner allows the burner to combust a wide range of fuel moisture contents without modifying the mechanical components of the burner.

A semiconductor device, in particular a solar cell, comprises a semiconductor substrate having a semiconductor substrate surface and a passivation composed of at least one passivation layer which surface-passivates the semiconductor substrate surface, wherein the passivation layer comprises a compound composed of aluminum oxide, aluminum nitride or aluminum oxynitride and at least one further element.

A resin composition, a multi-layered film, a backsheet for photovoltaic modules, a method thereof, and a photovoltaic module are provided. The multi-layered film including a coating layer including a fluorine-based polymer has an excellent durability and weather resistance, and also exhibits high interfacial adhesive strength to a substrate since the multi-layered film is formed by coating a cured product of the resin composition including the fluorine-based polymer, an acrylic polymer including a thermosetting functional group, and a heat-curing agent on the substrate. In addition, drying can be performed at a low temperature during the manufacture of the multi-layered film so that the manufacturing costs can be decreased, productivity can be increased, and the deterioration of the product due to heat modification, heat shock, and the like, can be prevented. The multi-layered film can be effectively used as a backsheet for various photovoltaic modules.

In one embodiment, harmful solar cell polarization is prevented or minimized by providing a conductive path that bleeds charge from a front side of a solar cell to the bulk of a wafer. The conductive path may include patterned holes in a dielectric passivation layer, a conductive anti-reflective coating, or layers of conductive material formed on the top or bottom surface of an anti-reflective coating, for example. Harmful solar cell polarization may also be prevented by biasing a region of a solar cell module on the front side of the solar cell.

A crack resistant solar cell module includes a protective package mounted on a frame. The protective package includes a polyolefin encapsulant that protectively encapsulates solar cells. The polyolefin has less than five weight percent of oxygen and nitrogen in the backbone or side chain. In other words, the combined weight percent of oxygen and nitrogen in any location in the molecular structure of the polyolefin is less than five. The polyolefin also has a complex viscosity less than 10,000 Pa second at 90° C. as measured by dynamic mechanical analysis (DMA) before any thermal processing of the polyolefin. The protective package includes a top cover, the encapsulant, and a backsheet. The solar cell module allows for shipping, installation, and maintenance with less risk of developing cracks on the surfaces of the solar cells.

A back electrode type solar cell in which a no-electrode-formed region where no electrode is placed is provided in a part of a peripheral portion of a back surface of the back electrode type solar cell such that a line connecting end portions of a plurality of electrodes to one another includes a partially inwardly recessed region and the no-electrode-formed region is located adjacent to each of an electrode for n-type and an electrode for p-type adjacent to each other, a solar cell module, a method of manufacturing a back electrode type solar cell with interconnection sheet, and a method of manufacturing a solar cell module are provided.

The present invention provides a photoelectric conversion material comprising a fullerene derivative represented by the formula C60(R1)5(R2), wherein each R1 independently represents an organic group having a substituent; and R2 represents a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group. Further, the present invention also provides a photoelectric conversion device having a self-assembled monomolecular film of the photoelectric conversion material, and a solar cell having the photoelectric conversion device.

The solar cell module includes a solar panel that includes a transparent substrate and is configured by aligning solar cells, a reinforcing frame arranged on the back surface of the solar panel, and a shock absorbing unit arranged between the solar panel and the reinforcing frame, where the shock absorbing unit has the first main surface facing the solar panel, which is a flat surface, and a second main surface facing the reinforcing frame, which is a curved surface bowed in the longitudinal direction of the reinforcing frame, having an arc shape in cross section, and convexed toward the reinforcing frame side.

A solar-cell sealant that has excellent properties such as transparency, flexibility, adhesiveness, heat resistance, appearance, cross-linking characteristics, electrical characteristics, and calenderability. A solar-cell sealant that contains an ethylene/α-olefin/unconjugated-polyene copolymer satisfying requirements (a1) through (a3). Requirement (a1) is that constituent units derived from ethylene constitute 80-90 mol %, constituent units derived from C3-20 α-olefin constitute 9.99-19.99 mol %, and constituent units derived from an unconjugated polyene constitute 0.01-5.0 mol % of said copolymer. Requirement (a2) is that the MFR of said copolymer, as measured in accordance with ASTM D1238 at 190° C. under a 2.16 kg load, be at least 2 g/10 min. and less than 10 g/10 min. Requirement (a3) is that the Shore A hardness of said copolymer, as measured in accordance with ASTM D2240, be 60 to 85.

A solar cell module includes a plurality of solar cells each comprising a substrate, an emitter region placed at the substrate, and an anti-reflection region placed on the emitter region. The anti-reflection region includes a first opening region through which part of the emitter region is exposed and one or more second opening regions through which part of the emitter region is exposed. A first electrode is connected to the exposed emitter region of the first opening region through the anti-reflection region by metal plating and a first bus bar is connected to the exposed emitter region of one or more second opening regions through the anti-reflection region by metal plating.

A multi-junction solar cell having a Ge or GaAs substrate, as well as a solar cell structure having several subcells deposited on the substrate, the substrate having peripheral side faces, and the solar cell structure having a peripheral circumferential surface, which runs spaced apart from the side faces. To prevent oxidation and penetration of moisture, the circumferential surface of the solar cell structure is coated with a protective, electrically insulating first coating under essential exclusion of the upper surface facing the rays, or that without encroaching on the solar cell structure, the side faces of the substrate are coated with a protective, electrically insulating second coating or that both the side faces of the substrate as well as the circumferential surface of the solar cell structure are coated with a third coating by essential exclusion of the upper surface facing the rays.

A method for regulating a web tension in a processing machine for processing a product web, in particular a shaftless printing press, includes separating a first product-web section from a second product-web section by a delay section. The web tensions in the first and second product-web sections are influenced by first and second actuators, respectively. To regulate the web tension in the first product-web section, the method further includes defining a regulation output value from which an actuating command for the first actuator is derived. An actuating command for the second actuator is defined from the regulation output value and a delay element to decouple the web tension in the second product-web section from the regulation of the web tension in the first product-web section. The delay element delays the effect of the regulation output value on the actuating command for the second actuator by a delay time.

A media diverter system for directing a media sheet traveling along an input media path into either a first media path or a second media path. One or more roller assemblies are provided including a media-guiding roller having one or more grooves formed around the exterior surface, and an air source for selectively providing an air flow into one or more of the grooves, the air flow being directed between the media sheet and the exterior surface of the media-guiding roller thereby producing a Bernoulli force to draw the media sheet toward the media-guiding roller. A controller selectively activates the air source in at least one of the roller assemblies while the corresponding media-guiding roller rotates around its roller axis to draw the media sheet toward the exterior surface of the media-guiding roller, thereby directing the media sheet into either the first media path or a second media path.

In a multiple endless belt type band sheet coiling tension applying apparatus in which a coiling tension is applied to slit band sheets a by a frictional force generated by slippage between belt pressing surfaces 4a, 5a and internal belt surfaces 1a of endless belts 1, a friction plate 8 made of a thin metallic sheet having heat conductivity equal to or better than that of the belt pressing units 4a, 5a is detachably installed on a front surface of each of the belt pressing units 4a, 5a.

An accumulating apparatus (4) has an upper arm (51) in which a plurality of upper rollers (511) are arranged, and a lower arm (52) in which a plurality of lower rollers (521) are arranged. An upper gear (61) is fixed to the upper arm and a lower gear (62) is fixed to the lower arm. The upper gear is engaged with the lower gear so that the upper arm and the lower arm are simultaneously moved in opposite directions with respect to a vertical direction. Therefore, when moving the lower arm in the vertical direction, influence of the weight of the lower arm is canceled by the weight of the upper arm, and a force to move the lower arm upward can be reduced. As the result, an air cylinder (63) for changing a distance between the upper arm and the lower arm can be downsized.

Groups of phase shifted Pulse Width Modulation signals are generated that maintain their duty-cycle and phase relationships as a function of the period of the PWM signal frequency. The multiphase PWM signals are generated in a ratio-metric fashion so as to greatly simplify and reduce the computational workload for a processor used in a PWM system. The groups of phase shifted PWM signals may also be synchronized with and automatically scaled to match external synchronization signals.

In an embodiment, a method of generating a pulse-width modulated signal from an input signal includes calculating a finite number of basis functions of a first pulse-width modulated signal based on the input signal, and forming an electronic output based on the calculated finite number of basis functions.

A phase-locked loop double-point modulator may include a frequency divider having a ratio which can be changed by a first modulation signal, and an oscillator, a frequency of which can be changed by a second modulation signal correlated to the first modulation signal. A calibration circuit may be configured, in a calibration mode, to match the gains of the first and second modulation signals based on frequency measurements of the oscillator for two different calibration values of the second modulation signal. The phase-locked double-point modulator may also include an attenuator having a constant ratio greater than 1 and placed in the path of the second modulation signal, and a selector switch configured to be controlled by the calibration circuit to reduce the ratio of the attenuator in the calibration mode.

An amplifier receives an amplitude signal of a polar modulated signal at a base terminal of a transistor and receives a phase modulated carrier signal of the polar modulated signal at the base terminal of the transistor. The amplifier combines the amplitude signal and the phase modulated signal to produce a full complex waveform at a collector terminal of the transistor.

A modulator generates a baseband digital signal from an information-bearing digital signal. The baseband signal has time-varying phase and amplitude defined by a sequence of complex data words, each having an in-phase (I) component and a quadrature (Q) component. A noise-shaping modulator generates a noise-shaped digital signal from the baseband digital signal such that quantization noise in the noise-shaping modulator is attenuated by a spectral null of its noise transfer function. The spectral null is selected by a noise-shaping parameter corresponding to a selected one of a plurality of output frequencies. A signal converter generates an analog signal conveying the information of the information-bearing digital signal on an analog carrier signal having the selected output frequency.

A new coded continuous phase modulation (CPM) scheme is proposed to enhance physical layer performance of the current DVB-RCS standard for a satellite communication system. The proposed CPM scheme uses a phase pulse design and combination of modulation parameters to shape the power spectrum of CPM signal in order to improve resilience to adjacent channel interference (ACI). Additionally, it uses a low complexity binary convolutional codes and S-random bit interleaving. Phase response using the proposed CPM scheme is a weighted average of the conventional rectangular and raised-cosine responses and provides optimum response to minimize frame error rate for a given data rate.

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.

A digital pulse width modulation controller includes a pulse width modulation controller, a selection unit having at least one selector, a comparison unit having at least one comparator, and a signal conversion unit having at least one digital-to-analog converter. The digital-to-analog converter generates a reference current and/or voltage. The comparator receives the reference current and/or voltage, and performs a comparison operation to generate a comparison signal based on a feedback signal. The selector selects one selection signal to input into the pulse width modulation controller, which receives other parameters set by a user or the system at the same time so as to control characteristics of the digital pulse width modulation signals, thereby improving the electric properties of a loading circuit.

Techniques and mechanisms for configuring logic to implement a signal modulation. In an embodiment, the logic includes a finite impulse response (FIR) module comprising circuitry. The selection circuitry may be operable to concurrently receive signals from latch circuitry of the FIR module and, based on the signals, to select an input group of the selection circuitry and to output a voltage identifier. In another embodiment, configuration logic is operable to set an operational mode which determines a total number of concurrent input signals, received by the FIR module, which the FIR module will use to select an input group for generating an output representing a voltage level.

A circuit includes a switched modulator stage combining an information signal with a square wave carrier to produce a first modulated signal; and a second modulation stage forming additional steps in the first modulated signal to produce a second modulated signal.

A rail-to-rail comparator including a first comparison unit connected to a first terminal and configured to compare differential input signals to differential reference voltages; a second comparison unit connected to a second terminal and configured to compare the differential input signals to the differential reference voltages; and an output unit configured to be driven in response to a clock signal and to generate a complementary output signal according to comparison results of the first and second comparison units.

An irrigation control device having a modulator that modulates data onto an alternating power signal by distorting amplitude of a first leading portion of selected cycles of the alternating power signal, and permit effectively a full amplitude of the alternating power signal on a following portion of the selected cycles, wherein the first leading portion and the following portion are either both on a high side of a cycle or both on a low side of a cycle of the alternating power signal. The irrigation control device further includes an interface configured to couple the modulator to a multi-wire interface coupled to a plurality of irrigation devices to permit the alternating power signal to be applied to the multi-wire interface.

An example PWM includes a driver and a two-way oscillator. The oscillator includes, a first frequency adjust current source, a second frequency adjust current source, a capacitor, a switching reference and a comparator. The capacitor integrates a frequency adjust current by charging with the first frequency adjust current source. The capacitor subsequently integrates a second frequency adjust current by discharging with the second frequency adjust current source. The switching reference outputs a first reference voltage and a second reference voltage responsive to an oscillator signal. The comparator compares the output of the switching reference with a voltage on the capacitor. The first and second frequency adjust current sources vary the first and second frequency adjust currents to vary the frequency of the PWM signal to spread energy of switching harmonics over a frequency band and to reduce EMI.

A time-varying formant is generated at a formant frequency by generating first and second harmonic phase signals having first and second harmonic numbers, respectively, in relation to a modulation frequency. The first and second harmonic phase signals are generated in proportion to a master phase signal, which varies at the modulation frequency, modulo a factor corresponding to their harmonic numbers. First and second sound signals, based on the first and second harmonic phase signals, are frequency modulated to create an arbitrarily rich harmonic spectrum, depending on an FM index. The time-varying formant is generated by generating a time-varying combination of the first and second harmonic sound signals, weighting the first and second harmonic sound signals in accordance with their spectral proximities to the formant frequency. One or more of the harmonic numbers are updated when the time-varying formant frequency passes the frequency of either sound signal.

A communications transmitter includes a baseband processor configured to generate amplitude, angle, in-phase and quadrature baseband signals and a combination modulator that is configurable to modulate in the polar domain and, alternatively, in the quadrature domain. The combination modulator includes a quadrature modulator and a separate and distinct angle modulator that is configured to serve as a local oscillator for the quadrature modulator. In one embodiment of the invention the combination modulator is configured to modulate in the quadrature domain when the transmitter is operating according to a first communications condition (e.g., first transmit power level or first modulation scheme) and is configured to modulate in the polar domain when the transmitter is operating according to a second communications condition (e.g., second transmit power level or second modulation scheme).

A device for mixing multiple (N) pulse density modulated (PDM) bit streams of a bit rate, the device comprises an input logic, an error accumulation circuit, an error correction circuit and an adder of more than N bits; wherein the device is arranged to output an output PDM bit stream that represents a mixture of the multiple input PDM bit streams; wherein the output PDM bit stream comprises a plurality of output PDM bits, wherein a certain output PDM bit of a plurality of output PDM bits that form the output PDM bit stream is generated during a certain clock cycle; wherein the input logic is arranged to select, during each fraction of the certain clock cycle, a current bit of a selected PDM bit stream, wherein different PDM bit streams are selected during different fragments of the certain clock cycle; wherein the error accumulation circuit is arranged to store intermediate values during a first fraction till a penultimate fraction of the certain clock signal and to store a last value during a last fraction of the certain clock signal.

A frequency modulating path for generating a frequency modulated clock includes a direct feed input arranged for directly modulating frequency of an oscillator, and a compensating feed input arranged for compensating effects of frequency modulating on a phase error; wherein the compensating feed input is resampled by a down-divided clock that is an integer edge division of the oscillator. A reference phase generator for generating a reference phase output includes a resampling circuit, an accumulator and a sampler. The resampling circuit is for resampling a modulating frequency command word (FCW) input to produce a plurality of samples. The accumulator is for accumulating the samples to generate an accumulated result. The sampler is for sampling the accumulated result according to a frequency reference clock, and accordingly generating a sampled result, wherein the reference phase output is updated according to at least the sampled result.

A frequency modulator includes a digitally-controlled oscillator (DCO) arranged for producing a frequency deviation in response to a modulation tuning word and a phase-locked loop (PLL) tuning word. In addition, another frequency modulator includes a DCO and a DCO interface circuit. The DCO is arranged for producing a frequency deviation in response to an integer tuning word and a fractional tuning word. The DCO interface circuit is arranged for generating the integer tuning word and the fractional tuning word to the DCO, wherein the fractional tuning word is obtained through asynchronous sampling of a fixed-point tuning word.

Embodiments of digital high-speed bi-phase modulator and method for bi-phase modulation are generally described herein. In some embodiments, the digital high-speed bi-phase modulator comprises a high-speed digital divider, a high-speed digital multiplexer, and matched signal paths provided between the divider and the multiplexer. The high-speed digital divider is configured to receive a carrier signal and generate complementary output signals. The high-speed digital multiplexer is configured to switch between the complementary output signals and generate a bi-phase modulated output at a carrier frequency (fc) modulated with a bi-phase code. The bi-phase code may be provided to control inputs of the multiplexer.

Provided is a method of generating a driving signal for driving a dual mode supply modulator for a power amplifier. The method includes obtaining an envelope of a complex baseband signal to be transmitted, comparing the envelope of the complex signal with a preset threshold value, when a current envelope of the complex signal is the preset threshold value or greater or when there is a result having the preset threshold value or greater in previous N comparisons, outputting a digital board output signal configured with a first logic level through a digital-to-analog converter; and when the current envelope of the complex signal is smaller than the preset threshold value and when there is no result having the preset threshold value or greater in the previous N comparisons, outputting a digital board output signal configured with a second logic level through the digital-to-analog converter.

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.