Abstract: A distortion compensating apparatus calculates a distortion compensation coefficient in such a manner that a difference signal between a reference signal, which is a transmit signal, and a feedback signal will be diminished, updates an old distortion compensation coefficient by the calculated distortion compensation coefficient and applies distortion compensation to the transmit signal based upon this distortion compensation coefficient. In this apparatus, a phase correcting interval, which is for correcting the phase difference between the reference signal and the feedback signal, and a distortion compensation coefficient updating interval are generated alternately, a correction is applied so as to null the phase difference in the phase correcting interval, and the distortion compensation coefficient is updated in the distortion compensation coefficient updating interval.

Abstract: A distortion compensation apparatus of the present invention is used in a transmitter that produces and outputs a second signal from a first signal. This apparatus comprises a delay unit for delaying a feedback signal obtained from by the second signal; and a delay control unit for determining a delay quantity of said delay means so that a timing difference between a reference signal obtained from the first signal and the feedback signal delayed by the delay unit is made small. The delay control unit limits the delay quantity within a predetermined limit value.

Abstract: A distortion compensating apparatus for correcting the size of a distortion compensation coefficient in such a manner that a transmit signal that has undergone distortion compensation will not exceed the dynamic range of a DA converter. Specifically, before a distortion compensation coefficient hn+1(p) that has been calculated by a calculation unit is stored in a coefficient memory, an assumption is made that distortion compensation will be performed using the distortion compensation coefficient hn+1(p). Then it is determined beforehand whether a signal x(t)*hn+1(p) that will be obtained by this distortion compensation will exceed the limit of a DA converter. If the limit will be exceeded, the size of the distortion compensation coefficient is reduced by a correction unit, the corrected distortion compensation coefficient is stored in the memory and the transmit signal is corrected using the stored distortion compensation coefficient.

Abstract: In a wireless communication apparatus in a time division duplex system, a transmission signal generation unit generates a transmission signal. A power amplifying device amplifies the generated transmission signal. A control signal generation device generates a drain voltage control signal for control of the drain voltage of the power amplifying device, and a gate voltage control signal for control of the gate voltage of the power amplifying device. The switch unit switches off the drain power supply of the power amplifying device during reception in the time division duplex system according to the drain voltage control signal. In addition, the power amplifying device sets a higher gate voltage during reception in the time division duplex system higher than during transmission according to the gate voltage control signal.

Abstract: The invention relates to a spread-signal multiplexing circuit for frequency-multiplexing a plurality of spread signals that were generated in parallel according to the SSMA scheme. An object of the invention is to adapt to various degrees of multiplicity and to keep the SN ratio and the power efficiency high. To this end, a spread-signal multiplexing circuit of the invention comprises an amplitude monitoring part for multiplexing a plurality of spread signals and determining amplitude of a resulting signal in time-series order; a delaying part for delaying the spread signals in parallel by a time that is equal to a propagation delay time of the amplitude monitoring part; and a multiplexing part for generating a multiplexed signal by multiplexing the delayed spread signals while weighting the delayed spread signals in parallel using weights that are smaller as an average value of the determined amplitude is larger.

Abstract: A control unit and a control method are disclosed. First and second changing units change impedances of two or more first and second components within predetermined first and second ranges, respectively, the first and the second components affecting an output signal. An evaluation function value calculating unit calculates an evaluation function value that is dependent on the impedances of the first and the second components. A gradient vector calculating unit calculates a gradient vector based on the difference between the evaluation function values before and after the impedance change of the second components. Based on the gradient vector, impedance of each of the first components is changed such that the evaluation function value takes a desired value.

Abstract: A communications apparatus using an adaptive antenna having in a high frequency unit an antenna unit including a plurality of antenna elements and a plurality of adjustment units, provided corresponding to the plurality of antenna elements, for adjusting directivity of an entire antenna, the communications apparatus including an interference wave element extraction unit for extracting an interference wave element other than a requested signal from a received signal by the antenna unit when an adjustment value of the adjustment unit is perturbed in a one symbol time, and an adaptive control unit for performing adaptive control on the adjustment value such that the extracted interference wave element can be minimized.

Abstract: Disclosed is an adaptive control apparatus having an error calculation unit for calculating the difference between a reference signal and a feedback signal, and an adaptive controller for applying adaptive control so as to diminish the difference and causing the result of adaptive control to be reflected in the reference signal. The adaptive control apparatus has a delay unit for delaying at least one of the reference signal and feedback signal by a set delay time in such a manner that the reference signal and feedback signal will be input simultaneously to the arithmetic unit; a frequency-component detecting unit for detecting a frequency component of the reference signal; a delay-time acquisition unit for acquiring delay time conforming to the frequency component; and a delay-time setting unit for setting the acquired delay time in the delay unit.

Abstract: Disclosed is a method of controlling direction of radio-wave emission of a base-station transmitter which emits radio waves upon providing the radio waves with directivity in the direction of a receiver. Two antennas of a base station that are disposed at different positions transmit first and second signals that have been spread by mutually orthogonal spreading codes. A mobile station has a phase detector for receiving the first and second signals transmitted from respective ones of the antennas and obtaining a phase difference between these signals, and a direction estimator for calculating the direction of the mobile station, as seen from the base station, based upon the phase difference and for feeding back a signal representing the calculated direction from the mobile station to the base station. The transmitter of the base station transmits data toward the receiver in the calculated direction using a directional antenna.

Abstract: A DC/DC converter capable of controlling an output signal using a broadband signal input is provided. By employing the above DC/DC converter as a power supply, a highly efficient power amplifier can be configured. The above DC/DC converter includes two class-C amplifiers, a rectifier circuit connected between each output of the two class-C amplifiers, and an oscillator of a predetermined frequency signal. The predetermined frequency signal output from the oscillator is input to each of the two class-C amplifiers, and by controlling the phase difference of the predetermined frequency signal input to the two class-C amplifiers, the magnitude of a direct current voltage output from the rectifier circuit is made variable.

Abstract: A MIMO wireless communication system and wireless communication apparatuses are disclosed that increase the practically usable communication channel capacity in the Shannon channel capacity that determines the ratio of maximum signal transmission speed to frequency. Each wireless communication apparatus includes antenna units that transmit and receive radio frequency signals, and a weight controlling unit that provides weights with respect to the antenna units. The antenna units are formed by adaptive array antenna units that can change the directivity by varying weights with respect to antenna elements.

Abstract: A code multiplexing transmitting apparatus spread-spectrum modulates transmission data of a plurality of channels by spreading codes that differ from one another, combines the spread-spectrum signals of each of the channels and transmits the resultant spread-spectrum modulated signal. A spread-spectrum modulating unit for each channel includes a phase shifter for shifting, by a predetermined angle channel by channel, the phase of a position vector of the spread-spectrum modulated signal of each channel. As the result of such phase control, the phases of pilot signal portions of the spread-spectrum modulated signals of the respective channels are shifted relative to one another so that the peak values of the code-multiplexed signal can be suppressed.

Abstract: A power amplifier negates a memory effect and is applied a linearizer using a digital predistortion system even in an inexpensive device. The power amplifier compares an input signal power against a sampled component of an output power, and provides predistortion to the input signal power so as to minimize a difference as a result of the comparison. The power amplifier comprises a gain lookup table storing a gain coefficient value corresponding to a temperature address determined for an input power; a phase lookup table storing a phase coefficient value corresponding to the temperature address determined for the input power; a transversal filter, which is input with the input power, and which outputs the temperature address; and a coefficient multiplier modulating the input signal using a gain coefficient value and a phase coefficient value, which correspond to the temperature address and which are read out from the gain coefficient lookup table and the phase lookup table.

Abstract: An RFID tag having a tag antenna and an LSI chip, comprising: a power-supply pattern on which the LSI chip is mounted; a patch antenna that functions as the tag antenna; and a high-frequency connection section that makes a high-frequency connection between the power-supply pattern and the patch antenna. The high-frequency connection section is formed, for example, by forming a slot in the patch antenna, layering one end of a small dipole antenna that functions as the power-supply pattern over the slot so that it crosses over the slot, and supplying power from the small dipole antenna to the patch antenna.

Abstract: A control device for an antenna matching circuit is configured to output an adjusting signal for changing impedance of an element in the antenna matching circuit based on change over time in signal power ratio of a reflected signal from the antenna matching circuit to an incident signal to the antenna matching circuit.

Abstract: A parallel operation system of transmission amplifiers enable the parallel running by the two distortion compensation amplifiers using the digital pre-distorter system and to provide a parallel operation system of the transmission amplifiers that makes it possible to switch to respective single running easily. The parallel operation system includes first and second transmission amplifiers which receive common input signals for outputting amplified signals from respective ones; and a coupling unit which combines outputs of the first and second transmission amplifiers, to provide as its output; the first and second transmission amplifiers each having a main amplifier; and a modulation unit disposed on the input side of the main amplifier; wherein the output of one of the modulation units included in the first and second transmission amplifiers is fed in common to the main amplifiers included in the first and second transmission amplifiers.

Abstract: An antenna comprises a dielectric member, an antenna pattern formed on one surface of the dielectric member, and a ground pattern formed on the other surface of the dielectric member. A part or the whole of the antenna is implanted in a dielectric layer on the side from which a laser beam does not come in of an optical recording medium symmetrically having a metal layer reflecting the laser beam and the dielectric layer, thereby to provide a radio tag antenna structure for an optical recording medium which is simple, is small-sized, and can secure necessary reading performance.

Abstract: The present invention reduces the scale of circuitry and shortens the code phase detection time needed to achieve initial synchronization. In a correlator for calculating correlation between a received spreading code contained in a received spread-spectrum signal and a reference spreading code, a combined code generator is included. The combined code generator outputs a combined spreading code by weighting and combining a plurality of phase-shifted reference spreading codes A1–AM. Further, an arithmetic circuit calculates correlation between the received spreading code and the plurality of phase-shifted reference spreading codes simultaneously. A phase detection circuit detects the phase difference between the received spreading code and a reference spreading code, namely the phase of the received spreading code from the results of the arithmetic operation.

Abstract: An antenna comprises a dielectric member, an antenna pattern formed on one surface of the dielectric member, and a ground pattern formed on the other surface of the dielectric member. A part or the whole of the antenna is implanted in a dielectric layer on the side from which a laser beam does not come in of an optical recording medium symmetrically having a metal layer reflecting the laser beam and the dielectric layer, thereby to provide a radio tag antenna structure for an optical recording medium which is simple, is small-sized, and can secure necessary reading performance.

Abstract: The distortion compensator which compensates the nonlinearity of a power amplifier in a radio communication device stops the operation of updating the automatic phase adjustment, automatic delay adjustment, equalizer adjustment, and distortion compensation table when something wrong is detected in the input to a distortion compensation unit such as a reference signal, feedback signal, address of the distortion compensation table, and phase value so that the distortion compensation coefficients may not be improperly updated.