Abstract: The present invention discloses magnesia and a method for manufacturing same, wherein the magnesia can be produced into granules of various shapes and sizes and can be improved in moisture resistance with the formation of a moisture resistant surface oxide layer by donor addition and then thermal treatment. The magnesia according to the present invention comprises a MgO granule; and a surface oxide layer formed on a surface of the MgO granule and a composition of the surface oxide layer is different from a composition of an inside of the MgO granule.

Abstract: Disclosed is a (K,Na)NbO3 (abbreviated by “KNN”)-based single crystal ceramic. The KNN-based single crystal ceramic according to the present disclosure is formulated by (K0.5?x/2Na0.5?x/2?y?y/2Mx+y/2)Nb1?x/3+yO3, wherein M indicates a metal having a different valence from Na, and ? indicates a metal vacancy. The above formulated KNN-based single crystal ceramic allows compensating for the volatilization of Na in a growing grain due to the addition of M2+ ions, and substituting M2+ ions for Na+ ions to form metal vacancies, thereby making possible the single crystal growth.

Abstract: Disclosed is a (K,Na)NbO3 (abbreviated by “KNN”)-based single crystal ceramic. The KNN-based single crystal ceramic according to the present disclosure is formulated by (K0.5?x/2Na0.5?x/2?y?y/2Mx+y/2)Nb1?x/3+yO3, wherein M indicates a metal having a different valence from Na, and ? indicates a metal vacancy. The above formulated KNN-based single crystal ceramic allows compensating for the volatilization of Na in a growing grain due to the addition of M2+ ions, and substituting M2+ ions for Na+ ions to form metal vacancies, thereby making possible the single crystal growth.

Abstract: An apparatus and a method for beamforming with less heat in a wireless communication system including multiple antennas are provided. The apparatus includes a digital signal processor for processing at least one baseband digital signal, and at least one Radio Frequency (RF) signal processor for converting a respective baseband digital signal of the at least one baseband digital signal into an RF analog signal and for amplifying a power of the RF analog signal for one or more antenna elements constituting a respective antenna of the at least one antenna.

Abstract: A wideband receiver for a wireless communication system and a method for controlling the same are provided. In the wideband receiver for a wireless communication system, a receive path includes a mixer for receiving a Radio Frequency (RF) signal having a frequency fSG and for converting the RF signal into an Intermediate Frequency (IF) signal having a frequency fIF by mixing the RF signal with a first local oscillation signal having a first local oscillation frequency fLO1, and at least one Phase Locked Loop (PLL) for providing the local oscillation signal to the mixer. A control block determines whether a half-IF signal having a center frequency of fSG?fIF/2 exists in the IF signal, and when the half-IF signal exists, controls the at least one PLL to generate a second local oscillation signal having a second local oscillation frequency fLO2 greater than the first local oscillation frequency fLO1.

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 transmitter is provided for amplifying signal power in a communication system. The transmitter includes a single-tone signal generator for generating a single-tone signal; a baseband signal generator for generating a baseband signal; a bias modulator for switching a positive bias signal to a first power amplifier using the baseband signal, and switching a negative bias signal to the second power amplifier using the baseband signal; the first power amplifier for power-amplifying the single-tone signal using the positive bias signal; and the second power amplifier for power-amplifying the single-tone signal using the negative bias signal.

Abstract: An apparatus and a method for a bias modulator using a Zero Current Switching (ZCS) are provided. The bias modulator includes a Pulse Width Modulation (PWM) signal generator for converting an input envelope signal to a PWM signal; a PWM/ZCS converter for calculating the number of ZCS control signals to be provided within an on-time duration of the PWM signal and generating at least one ZCS control signal according to the number of the ZCS control signals; and a ZCS switching regulator for generating a bias current according to the ZCS control signal.

Abstract: A wideband receiver for a wireless communication system and a method for controlling the same are provided. In the wideband receiver for a wireless communication system, a receive path includes a mixer for receiving a Radio Frequency (RF) signal having a frequency fSG and for converting the RF signal into an Intermediate Frequency (IF) signal having a frequency fIF by mixing the RF signal with a first local oscillation signal having a first local oscillation frequency fLO1, and at least one Phase Locked Loop (PLL) for providing the local oscillation signal to the mixer. A control block determines whether a half-IF signal having a center frequency of fSG-fIF/2 exists in the IF signal, and when the half-IF signal exists, controls the at least one PLL to generate a second local oscillation signal having a second local oscillation frequency fLO2 greater than the first local oscillation frequency fLO1.

Abstract: An apparatus and method for attenuating a leakage signal of a transmitter in a communication system is provided. The apparatus includes a local oscillator, a mixer, and a leakage signal attenuator. The local oscillator outputs a reference frequency signal. The mixer adds the reference frequency signal to an IF signal to convert the IF signal into an RF signal, and outputs the RF signal, a leakage signal and an image signal. The leakage signal attenuator extracts a partial signal from the reference frequency signal output from the local oscillator, adjusts the amplitude of the extracted signal, shifts the phase of the extracted signal, and combines the resulting signal and the output signal of the mixer, to remove the leakage signal.

Abstract: An apparatus and a method for a bias modulator using a Zero Current Switching (ZCS) are provided. The bias modulator includes a Pulse Width Modulation (PWM) signal generator for converting an input envelope signal to a PWM signal; a PWM/ZCS converter for calculating the number of ZCS control signals to be provided within an on-time duration of the PWM signal and generating at least one ZCS control signal according to the number of the ZCS control signals; and a ZCS switching regulator for generating a bias current according to the ZCS control 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.

Abstract: A transmitter is provided for amplifying signal power in a communication system. The transmitter includes a single-tone signal generator for generating a single-tone signal; a baseband signal generator for generating a baseband signal; a bias modulator for switching a positive bias signal to a first power amplifier using the baseband signal, and switching a negative bias signal to the second power amplifier using the baseband signal; the first power amplifier for power-amplifying the single-tone signal using the positive bias signal; and the second power amplifier for power-amplifying the single-tone signal using the negative bias signal.

Abstract: An apparatus and a method for beamforming with less heat in a wireless communication system including multiple antennas are provided. The apparatus includes a digital signal processor for processing at least one baseband digital signal, and at least one Radio Frequency (RF) signal processor for converting a respective baseband digital signal of the at least one baseband digital signal into an RF analog signal and for amplifying a power of the RF analog signal for one or more antenna elements constituting a respective antenna of the at least one antenna.

Abstract: An apparatus and method for attenuating a leakage signal of a transmitter in a communication system is provided. The apparatus includes a local oscillator, a mixer, and a leakage signal attenuator. The local oscillator outputs a reference frequency signal. The mixer adds the reference frequency signal to an IF signal to convert the IF signal into an RF signal, and outputs the RF signal, a leakage signal and an image signal. The leakage signal attenuator extracts a partial signal from the reference frequency signal output from the local oscillator, adjusts the amplitude of the extracted signal, shifts the phase of the extracted signal, and combines the resulting signal and the output signal of the mixer, to remove the leakage signal.

Abstract: A calibration apparatus and method in a communication system are provided. In the apparatus and method, baseband reference signals are generated for signal transmission paths, upconverted to RF signals, and downconverted to a baseband signal after coupling and combining, and transmission calibration vectors are acquired using the baseband signal, and a reference signal is generated, upconverted to an RF signal, distributed to signal reception paths, coupled, and downconverted to baseband signals, and reception calibration vectors are acquired using the baseband signals. Accordingly, the apparatus and method perform calibration without the need for using additional Tx and Rx hardware in a communication system which minimizes system complexity.

Abstract: A transmitting apparatus in a TDD wireless communication system is provided. In the transmitting apparatus, a circulator transmits a signal received from a power amplifier to an antenna feed line and transmits a signal received from the antenna feed line to a quarter-wave transmission line. The quarter-wave transmission line is installed in a reception path, for reception isolation in a transmission mode. An RF switch shorts the load of the quarter-wave transmission line to the ground or connects the load of the quarter-wave transmission line to an LNA according to a control signal. The LNA low-noise-amplifies a signal received from the RF switch.