Abstract: A signal transmission apparatus comprises a plurality of look-up tables (LUTs) corresponding to operation areas of a nonlinear transmission device, an operational characteristic calculator, a LUT selector, and a predistorter. The LUTs are adapted to store gain values of input signal magnitudes. The LUT selector selects a LUT corresponding to a calculated operational characteristic. The selected LUT generates a gain value output signal. The predistorter generates a predistorted signal from the gain value output signal and an input signal. The predistorted signal is input to a nonlinear transmission device.

Abstract: An apparatus and method that compensates for pre-distortion of a power amplifier includes a digital pre-distorter controller which generates a power/phase compensation coefficient, a temperature compensation coefficient and a frequency compensation coefficient, a look-up table which stores the coefficients, a pre-distorter kernel which pre-compensates an input signal based on the temperature compensation coefficient from the look-up table, and a correction filter which compensates an output signal of the kernel based on the frequency compensation coefficient from the look-up table. If desired, an input signal may be pre-distorted based on only one of the temperature and frequency compensation coefficients along with the power/phase compensation coefficient. Nonlinear characteristics of the power amplifier are accurately checked and distortion due to the nonlinear characteristics are compensated for.

Abstract: A vector modulator is disclosed which includes a first amplitude invariant phase shifter for shifting a phase of a received signal at fixed intervals within a preset first shifting range and a quadrature hybrid coupler for separating an output of the first amplitude invariant phase shifter into at least two different channel signals having a 90° phase difference to each other. A second amplitude invariant phase shifter shifts a phase of a first channel signal among outputs of the quadrature hybrid coupler by a fixed amplitude within a prescribed second shifting range and a third amplitude invariant phase shifter shifts a phase of a second channel signal among outputs of the quadrature hybrid coupler by a fixed amplitude within a prescribed third shifting range.

Abstract: A signal transmission apparatus comprises a plurality of look-up tables (LUTs) corresponding to operation areas of a nonlinear transmission device, an operational characteristic calculator, a LUT selector, and a predistorter. The LUTs are adapted to store gain values of input signal magnitudes. The LUT selector selects a LUT corresponding to a calculated operational characteristic. The selected LUT generates a gain value output signal. The predistorter generates a predistorted signal from the gain value output signal and an input signal. The predistorted signal is input to a nonlinear transmission device.

Abstract: An apparatus and method that compensates for pre-distortion of a power amplifier includes a digital pre-distorter controller which generates a power/phase compensation coefficient, a temperature compensation coefficient and a frequency compensation coefficient, a look-up table which stores the coefficients, a pre-distorter kernel which pre-compensates an input signal based on the temperature compensation coefficient from the look-up table, and a correction filter which compensates an output signal of the kernel based on the frequency compensation coefficient from the look-up table. If desired, an input signal may be pre-distorted based on only one of the temperature and frequency compensation coefficients along with the power/phase compensation coefficient. Nonlinear characteristics of the power amplifier are accurately checked and distortion due to the nonlinear characteristics are compensated for.

Abstract: A predistortion linearizer of a power amplifier capable of improving the nonlinearity of the power amplifier by compensating changes in the power amplifier's nonlinear characteristics according to the lapse of time or an external environment and easily implementing the reverse characteristics of the power amplifier's nonlinear characteristics is disclosed. The predistortion linearizer of the power amplifier as disclosed includes a control unit for controlling a gain and phase of an input signal so that they are the reverse of the power amplifier's nonlinear characteristics, and a unit for compensating changes in the power amplifier's distortion characteristics according to the lapse of time or an external environment, upon receipt of the output of the control unit.

Abstract: An AQM error compensating apparatus includes: a predistorter for distorting a signal so as to have the opposite characteristics of nonlinear distortion characteristics of a digital input signal; an error compensating unit for compensating I/Q digital signals outputted from the predistorter according to an error correction signal; a digital/analog converter for converting the I/Q digital signals of the error compensating unit into I/Q analog signals; a modulator for frequency-modulating the I/Q analog signals outputted from the digital/analog converter; a power amplifier for amplifying the output signal of the modulator to a directional coupler; a down-converter for down-converting a feedback signal inputted from the directional coupler; an analog/digital converter for converting the output signal of the down-converter into a digital signal; and a controller for comparing the output signal of the analog/digital converter with the I/Q digital signals inputted from the predistorter, and applying an extracted err

Abstract: An adaptive predistortion transmitter is disclosed. The transmitter includes a predistortion unit that distorts a digital input signal to have a non-linear characteristic opposite to that of the whole transmitter. A radio frequency converter converts an output signal of the predistortion unit into a radio frequency signal and an HPA amplifies the radio frequency converter. An error detector detects a non-linear characteristic change of the whole transmitter, by comparing the digital input signal and the output signal of the HPA, and controls an operation of the predistortion unit. The predistortion unit is implemented in consideration of the non-linear characteristic of the whole transmitter, including the up-converter and the HPA. Thus, the non-linear characteristic of the transmitter can be effectively improved. In addition, since the predistortion unit and a direct IF up-converter are implemented in one chip, the design structure of the whole transmitter can be simplified.

Abstract: A predistortion linearizer of a power amplifier capable of improving the nonlinearity of the power amplifier by compensating changes in the power amplifier's nonlinear characteristics according to the lapse of time or an external environment and easily implementing the reverse characteristics of the power amplifier's nonlinear characteristics is disclosed. The predistortion linearizer of the power amplifier as disclosed includes a control unit for controlling a gain and phase of an input signal so that they are the reverse of the power amplifier's nonlinear characteristics, and a unit for compensating changes in the power amplifier's distortion characteristics according to the lapse of time or an external environment, upon receipt of the output of the control unit.

Abstract: A system for sensing the operating state of a tower top amplifier for mobile communication system, includes a plurality of tower top amplifiers each connected to communication antennas; and an operating state management part monitoring the operating state of each tower top amplifier. The operating state management part monitors the operating state of each tower top amplifier by the use of a single power supply line connected between itself and each tower top amplifier. In a method of sensing the operating state of a tower top amplifier for mobile communication system, the operating state of each tower top amplifier is monitored by using an amount of consumed DC power applied to the respective tower top amplifiers. This method includes the steps of measuring a potential difference of a given section of the DC power applied to each tower top amplifier; and comparing a result obtained by the measuring step and determining the normal or abnormal states of the tower top amplifiers.