Fujitsu Corporation

Takao Sasaki

Hiromi Miyamoto

Hideharu Shako

Takeshi Ohba

Yasuhito Funyu

Tadayoshi Katoh

Masafumi Shigaki

Tomoyuki Arai

Shinji Yamaura

Masayuki Oonuki

A phase shifter includes a phase shifting unit for operating at a timing at which a clock signal becomes equal to or greater than a threshold value and outputting periodic signals having phases shifted by 90 degrees from each other; a DC voltage setting unit for setting a voltage value of a DC component of the clock signal input into the phase shifting means; and a clock signal slope varying unit for varying a slope of a rising edge of the clock signal.

Phase shifter

A semiconductor integrated circuit which is connected to a substrate by solder bumps wherein, when at least one solder bump is connected to a signal line of the semiconductor integrated circuit and the semiconductor integrated circuit is mounted on the substrate, the semiconductor integrated circuit is bonded to the substrate by the solder bump, and the interconnection to the substrate is made by dummy bumps forming wires at the substrate side.

Semiconductor integrated circuit with solder bump

A power control circuit includes: a fine adjustment variable amplifying unit configured to amplify the input signal in accordance with a first gain set value; a coarse adjustment variable amplifying unit configured to amplify the input signal in accordance with a second gain set value; a branching unit configured to branch an output signal into a feedback signal; a comparing unit configured to compare a gain value between the input signal and the output signal with the required gain set value; a control unit configured to determine the first gain set value and the second gain set value based on the required gain set value; and an adjusting unit configured to adjust the first gain set value and the second gain set value so that the power value of the feedback signal becomes a power value corresponding to the required gain set value.

Power control circuit and power control method

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

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.

Distortion compensating amplifier device, amplifier system, and wireless base station

A linearizer includes an input terminal, an output terminal, and a field-effect transistor having a gate connected to the input terminal, a drain connected to the output terminal and a source grounded. A supply voltage is supplied through a load circuit to the drain of the transistor. A gate voltage is supplied through a bias line to the gate of the transistor. The transistor is biased at a bias point at which a drain current of the transistor in response to the gate voltage is in an unsaturated region.

Linearizer for power amplifier

The system allows a plurality of earth stations to communicate with one another by relaying transmission signals via satellites circling the earth in high earth and low earth orbits. A geostationary satellite operates in a geostationary orbit, while a plurality of low-earth orbiting satellites circle the earth in low-earth orbits. Those satellites serve as repeaters for the communications between a first earth station and a second earth station. Tracking relay means, disposed in the geostationary satellite, tracks only a limited number of low-earth orbiting satellites within an orbital range that corresponds to a predetermined area on the earth. Accordingly, the tracking relay means relays transmission signals of the second earth station to the low-earth orbiting satellites only when they are within the orbital range.

Growing community of inventors

Kawasaki, Japan

Takao Sasaki