Abstract:
A distortion compensator compensates for distortion of a signal caused by an amplifier. A storage section stores a plurality of compensation coefficients used for distortion compensation. A selection section selects a compensation coefficient corresponding to an index value indicative of a power level of the signal from among the plurality of compensation coefficients. The selection section determines whether or not the power level is higher than a threshold, and uses, based on a determination result, a first index value calculated without using a logarithmic operation or a second index value calculated by using a logarithmic operation.
Abstract:
A distortion compensating apparatus that compensates signal distortion caused by an amplifier includes a distortion compensating process unit that using a distortion compensation coefficient, compensates distortion of an input signal; a memory unit storing therein the distortion compensation coefficient; and an address generating unit that generates a first address that is based on electrical power of the input signal and is for acquiring the distortion compensation coefficient from the memory unit, and a second address that is based on any one among the electrical power, phase of the input signal and amplitude of the input signal, is for acquiring the distortion compensation coefficient from the memory unit, and is normalized in a normalizing range determined according to the electrical power of the input signal. The distortion compensating process unit acquires the distortion compensation coefficient from the memory unit, based on the first and the second addresses to compensate the distortion.
Abstract:
A distortion compensation device includes a storage unit storing a plurality of distortion compensation coefficients associated with power values of transmission signals, a distortion compensation processing unit acquiring a distortion compensation coefficient corresponding to a power value of a received transmission signal from among the plurality of distortion compensation coefficients and subjecting the received transmission signal to a distortion compensation process on the basis of the acquired distortion compensation coefficient, a phase calculating unit calculating a phase correction value on the basis of the distortion compensation coefficients, a phase correcting unit generating a reference signal by correcting a phase of the received transmission signal on the basis of the phase correction value, and a correction processing unit performing a correction process for the transmission signal subjected to the distortion compensation process on the basis of the reference signal and a feedback signal from a transmission power amplifier.
Abstract:
A distortion compensating apparatus that compensates signal distortion caused by an amplifier includes a distortion compensating process unit that using a distortion compensation coefficient, compensates distortion of an input signal; a memory unit storing therein the distortion compensation coefficient; and an address generating unit that generates a first address that is based on electrical power of the input signal and is for acquiring the distortion compensation coefficient from the memory unit, and a second address that is based on any one among the electrical power, phase of the input signal and amplitude of the input signal, is for acquiring the distortion compensation coefficient from the memory unit, and is normalized in a normalizing range determined according to the electrical power of the input signal. The distortion compensating process unit acquires the distortion compensation coefficient from the memory unit, based on the first and the second addresses to compensate the distortion.
Abstract:
An error between the power of an input signal, which is input to a power amplifier, and the power of an output signal, which is output from the power amplifier, is calculated. The calculated error is normalized according to the power of the input signal or the power of the output signal. A distortion correction coefficient, which is stored in a predetermined storage unit in association with the power of the input signal, is updated using the normalized error.
Abstract:
A distortion compensating technique applied to a transmitter for transmitting a quadrature modulated signal in a wireless digital communication system is provided. A phase adjustment value is determined for a quadrature demodulated feedback signal based on comparison between the feedback signal and a reference signal to be transmitted from the transmitter. This phase adjustment value is compared with the previous phase adjustment value. If the comparison result between the current and previous phase adjustment values satisfies a prescribed condition, correction for quadrature modulation, such as DC offset correction, orthogonality correction, or IQ amplitude correction, is performed.
Abstract:
A direct-current-offset correction device includes a digital-to-analog converter that converts a digital signal into an analog signal, a modulator that modulates the analog signal to generate a modulated signal, a direct-current-offset correction value calculation unit that calculates a direct-current-offset correction value as a reverse characteristic component of a carrier leak occurring in the modulated signal based on a demodulated signal which is demodulated by feeding back the modulated signal, a direct-current-offset correction unit that corrects a direct-current-offset on the digital signal based on the direct-current-offset correction value, a correction value detection unit that detects whether or not the direct-current-offset correction value is zero or a neighboring value of zero, and an offset generation unit that superimposes a direct-current-offset component on the analog signal based on a detection result of the correction value detection unit.
Abstract:
A distortion compensation apparatus shortens the time until start of the transmission. The distortion compensating apparatus for amplifying the transmitted signal after implementation of the distortion compensation process thereto comprises a coefficient memory operable to store coefficients used for the distortion compensation process, an initial value memory operable to store the initial values of the coefficients, and a controller which controls the coefficient memory to store, with limitation, only the coefficients corresponding to the first portion among those stored in the initial value memory for the initial write to the coefficient memory and to store thereafter the coefficients corresponding to the second portion.
Abstract:
A distortion compensation apparatus is provided to restrain an increased calculation time caused by a large amount of calculation required for obtaining a phase variation amount for compensation from the correlation. The distortion compensation apparatus includes an update calculation section calculating a distortion compensation coefficient by use of an adaptive algorithm; a distortion compensation section performing distortion compensation to the transmission signal, based on the distortion compensation coefficient being read out from the distortion compensation coefficient storage; a correlation calculation section calculating a real part of correlation and an imaginary part of correlation of each the reference signal and the feedback signal; and a phase rotation section compensating a relative phase deviation between the reference signal and the feedback signal, based on the real part of correlation and the imaginary part of correlation calculated by the correlation calculation section, wherein the update calculation section calculates a distortion compensation coefficient using the post-compensation signal.
Abstract:
To shorten the time required for writing of the distortion compensation coefficient and to reduce amount of data of the distortion compensation coefficient stored as the initial value of the distortion compensation apparatus. The distortion compensation apparatus for amplifying the transmitting signal after implementing the distortion compensation process comprises a coefficient memory for storing corresponding to each address the coefficient used for the distortion compensation process, an initial value memory for storing the initial value of the coefficient, and a controller for write control corresponding to n (n: natural number equal to 2 or larger) addresses of the coefficient read from the initial value memory corresponding to one address.