Abstract: Disclosed is a method of manufacturing a polyurethane filter foam having excellent air permeability, elasticity, and restoring force. In the method of manufacturing the polyurethane filter foam, the cell size of the filter foam is made regular by controlling the pressure by adjusting the diameter of the foaming head of a foaming machine, rather than adding a cell opener, cell irregularity caused by poor dispersion of the cell opener is alleviated, and air permeability, porosity, and compression set are excellent.

Abstract: The purpose of the present invention is to reduce the Peak-to-Average Ratio (PAR) of a transmission signal. A transmission device includes a generation part for generating a cancellation pulse corresponding to a peak component of a transmission signal, and a cancellation part for attenuating the peak component using the cancellation pulse. In addition, the present invention includes some embodiments other than the aforesaid embodiment.

Abstract: Provided is a Digital Pre-Distortion (DPD) apparatus and method for processing a signal that is input to a power amplifier in a wireless communication system. The DPD apparatus includes a DPD unit configured to pre-distort an input signal that is input to the power amplifier, using DPD information; and a signal processor configured to capture signals for estimation of the DPD information from each of an input terminal and an output terminal of the power amplifier, detect peak signals of the captured signals, separate the detected peak signals into a plurality of intervals depending on a power level, separately store the detected peak signals, estimate the DPD information using the peak signals stored for each interval, and provide the estimated DPD information to the DPD unit.

Abstract: The purpose of the present invention is to reduce the Peak to Average Ratio (PAR) of a transmission signal. A transmission device comprises a generation part for generating a cancellation pulse corresponding to a peak component of a transmission signal, and a cancellation part for attenuating the peak component using the cancellation pulse. In addition, the present invention includes some embodiments other than the aforesaid embodiment.

Abstract: Provided is a Digital Pre-Distortion (DPD) apparatus and method for processing a signal that is input to a power amplifier in a wireless communication system. The DPD apparatus includes a DPD unit configured to pre-distort an input signal that is input to the power amplifier, using DPD information; and a signal processor configured to capture signals for estimation of the DPD information from each of an input terminal and an output terminal of the power amplifier, detect peak signals of the captured signals, separate the detected peak signals into a plurality of intervals depending on a power level, separately store the detected peak signals, estimate the DPD information using the peak signals stored for each interval, and provide the estimated DPD information to the DPD unit.

Abstract: An apparatus and a method for operating a memory compensation Digital Pre-Distortion (DPD) are provided. In the method for operating a memory compensation DPD system, an input signal is received. An input average power of the input signal is determined. When the input average power of the input signal belongs to a non-linear section of the input average power, DPD is performed on a previous signal corresponding to a memory degree set depending on at least one non-linear section of the input average power.

Abstract: A digital pre-distortion system and method are provided. The method includes performing a digital pre-distortion operation; and limiting an input of the power amplifier to be no greater than a limit threshold.

Abstract: A digital pre-distortion system and method are provided. The method includes performing a digital pre-distortion operation; and limiting an input of the power amplifier to be no greater than a limit threshold.

Abstract: A method and apparatus improve the performance of a carrier amplifier in a Doherty amplifier. The Doherty amplifier includes a power divider, a carrier amplifier, at least one peaking amplifier, offset lines, and a Doherty circuit. The power divider provides a power signal to each of the carrier amplifier and the at least one peaking amplifier. The carrier amplifier amplifies power of a signal inputted from the power divider. The at least one peaking amplifier amplifies power of a signal inputted from the power divider. The offset lines control a load impedance when the at least one peaking amplifier does not operate. When the at least one peaking amplifier does not operate, the Doherty circuit generates the load impedance of the carrier amplifier that is larger than twice a load impedance at the maximum output power of the carrier amplifier.

Abstract: An apparatus and method for maximizing the performance of a peaking amplifier in a Doherty amplifier are provided. The apparatus includes a splitter, a carrier amplifier, an (N?1) number of peaking amplifiers, a Doherty combiner, and an output load. The splitter splits an input signal into an ‘N’ number of power signals. The carrier amplifier amplifies the signal provided from the splitter using a first Direct Current (DC) bias. The peaking amplifiers amplify the signals provided from the splitter using a second DC bias, which is lower than the first DC bias. When the carrier amplifier and the peaking amplifiers are all operating, the Doherty combiner forms a load impedance of the respective amplifiers such that the load impedance of the peaking amplifiers are less than the load impedance of the carrier amplifier. The output load outputs the signals amplified by the carrier amplifier and the peaking amplifiers.

Abstract: An apparatus and a method for an Envelope Elimination and Restoration (EER) power transmitter are provided. The apparatus includes a signal separator for splitting a transmit signal to an amplitude component and a phase component, an orthogonal modulator for modulating the phase component into a Radio Frequency (RF) signal, a bias modulator for linearly amplifying the amplitude component, for determining a bias voltage according to a magnitude of the amplitude component, and for providing a current generated using the determined bias voltage to a high-efficiency power amplifier and the high-efficiency power amplifier for amplifying the RF signal using the linearly amplified amplitude component as a drain bias voltage and using the generated current as a drain bias current.

Abstract: A method an apparatus improve linearization performance and reduce a convergence time of a Digital Pre-Distorter of a power amplifier. An input signal is received. A peak level of the input signal is expanded based on an expansion threshold. And the expanded peak level of the input signal is linearized through Digital Pre-Distorter (DPD) training on the expanded input signal.

Abstract: A method and apparatus improve the performance of a carrier amplifier in a Doherty amplifier. The Doherty amplifier includes a power divider, a carrier amplifier, at least one peaking amplifier, offset lines, and a Doherty circuit. The power divider provides a power signal to each of the carrier amplifier and the at least one peaking amplifier. The carrier amplifier amplifies power of a signal inputted from the power divider. The at least one peaking amplifier amplifies power of a signal inputted from the power divider. The offset lines control a load impedance when the at least one peaking amplifier does not operate. When the at least one peaking amplifier does not operate, the Doherty circuit generates the load impedance of the carrier amplifier that is larger than twice a load impedance at the maximum output power of the carrier amplifier.

Abstract: An apparatus and method for maximizing the performance of a peaking amplifier in a Doherty amplifier are provided. The apparatus includes a splitter, a carrier amplifier, an (N?1) number of peaking amplifiers, a Doherty combiner, and an output load. The splitter splits an input signal into an ‘N’ number of power signals. The carrier amplifier amplifies the signal provided from the splitter using a first Direct Current (DC) bias. The peaking amplifiers amplify the signals provided from the splitter using a second DC bias, which is lower than the first DC bias. When the carrier amplifier and the peaking amplifiers are all operating, the Doherty combiner forms a load impedance of the respective amplifiers such that the load impedance of the peaking amplifiers are less than the load impedance of the carrier amplifier. The output load outputs the signals amplified by the carrier amplifier and the peaking amplifiers.

Abstract: An apparatus and method for enhancing performance of a Doherty power amplifier are provided. The method includes a signal separation unit for generating a first input signal serving as an input signal of a carrier power amplifier using an input signal and a second input signal serving as an input signal of a peaking power amplifier using the input signal, in which the first input signal is different from the second input signal.

Abstract: An apparatus and a method for an Envelope Elimination and Restoration (EER) power transmitter are provided. The apparatus includes a signal separator for splitting a transmit signal to an amplitude component and a phase component, an orthogonal modulator for modulating the phase component into a Radio Frequency (RF) signal, a bias modulator for linearly amplifying the amplitude component, for determining a bias voltage according to a magnitude of the amplitude component, and for providing a current generated using the determined bias voltage to a high-efficiency power amplifier and the high-efficiency power amplifier for amplifying the RF signal using the linearly amplified amplitude component as a drain bias voltage and using the generated current as a drain bias current.