Fujitsu Corporation

Hiromi Miyamoto

Takao Sasaki

Hideharu Shako

Takeshi Ohba

Yasuhito Funyu

Yoshiaki Nakano

Ichiro Abeno

Masayuki Oonuki

Provided is a distortion compensation apparatus which can correspond to the number of carriers adaptively. The apparatus includes a distortion compensation processing circuit multiplying an input signal by a distortion compensation coefficient; a distortion compensation coefficient storage storing the distortion compensation coefficient correspondingly to the input signal power; a distortion compensation coefficient calculator calculating an update value of the distortion compensation coefficient stored in the distortion compensation coefficient storage, based on the input signal and a feedback signal being feedbacked from the output side of a distortion device; a digital filter inputting the output of the distortion compensation processing circuit. Further is included a modifying unit, which modifies the passband of the digital filter so as to reduce a distortion compensation control bandwidth in the predistortion portion, in response to the reduction of the number of carriers in the input signal.

Distortion compensation apparatus

Disclosed is a distortion compensating amplifier having a distortion compensator for compensating for distortion of an amplifier by updating distortion compensation coefficients so as to null a difference between a transmit signal and a feedback signal, and subjecting the transmit signal to distortion compensation processing using the distortion compensation coefficients, an amplifier for amplifying the transmit signal, which has undergone distortion compensation, in order to transmit the signal from an antenna, and a feedback unit for inputting an output signal from the amplifier to a distortion compensation coefficient updater in the distortion compensator as the feedback signal. Whether the level of an unwanted-wave signal that penetrates the amplifier from space via an antenna is greater than a set level is monitored. If the level of the unwanted-wave signal is above the set level, processing for updating distortion compensation coefficients is suspended. If the level of the unwanted-wave signal is below the set level, then processing for updating distortion compensation coefficients is resumed.

Distortion compensating amplifier

In a signal cancellation method and device which can cancel input signals quickly and reliably (stably), an input signal is split into a first and second signal. The second signal is split into mutually orthogonal first and second subsignals which are recombined after the respective amplitudes thereof have been adjusted, The first signal is canceled by the third signal thereby obtained. The orthogonal subsignals can undergo amplitude adjustment independently, and the third signal obtained by recombining the subsignals after adjustment can become a cancellation signal having a really selected phase and amplitude over the first through fourth quadrants of the vector plane.

Signal canceling method and device

A distortion compensating amplifier device is disclosed that maintains uniform delay amounts between a transmission input signal and a transmission output signal, even if there is a change in the device characteristics. The distortion compensating amplifier device of a digital predistortion type includes a second delay circuit that delays the transmission input signal; a distortion compensating circuit that performs predistortion compensation on the delayed signal, using a distortion compensating parameter; an amplifier that amplifies the signal subjected to the predistortion compensation; a first delay circuit that further delays the signal delayed by the second delay circuit; and a calculator that calculates the distortion compensating parameter to be used in the predistortion compensation, based on the difference between the signal output from the first delay circuit and the amplified signal.

Growing community of inventors

Kawasaki, Japan

Hiromi Miyamoto